2 Speed Fan Poser will my woes end!

[rovertone]

Have just arrived in Portugal having towed my 1420kg caravan with my Cdti Auto remapped 160.
Ran superbly until I came to a very long steep climb in Spain 1400 mtrs over 3/4kms (Hgv's crawling with hazards on) when temp gauge started to rise and engine went into limp mode, tried to keep revs as low as possible and made it with engine fading and picking up several times. Same thing happened after a further 200 kms, and on another nearly as steep climb temp went up but engine didn't fade. Completed rest of journey with no problems including many long steady climbs, gauge not moving from half way car pulling like a train.
Has anyone else experienced anything similar, is it the exceptional climbs with the load or could 2nd fan speed not be kicking in (it runs when a/c is switched on), is it possible to check it? I am sure when I had the remap not long back the fan was checked out ok albeit still with the original silver resistor.
I have a bit of time before the journey home and wonder whether I should be doing anything to give me 'peace of mind'. This is the first time I have towed such a long distance, up until this issue I have never had a temperature problem. Any thoughts would be most welcome.

[T-Cut]

When an engine works hard it will get hotter than usual, including the diesel. How hot will depend to a large extent on the integrity of the cooling system. The radiator fan must work as designed to keep the engine within normal temperature limits. On the diesel, the low speed should trip on at 105C or so. Since you have the later 2-speed fan, the slow speed resistor should be checked because they're prone to failure. This causes loss of fan cooling until the engine's much hotter. The resistor/low speed can be checked by running the so-called Demist test.

With a cool engine, turn the ignition on and press the Demist button. This effectively invokes the aircon system which requires the slow speed fan. It should start immediately and run continuously until Demist is pressed again (off). If the fan doesn't start immediately, then the resistor has failed. If you repeat the test with the engine on tick-over, the high speed fan will eventually start up and pulse on and off every 10-30 seconds. This is the emergency cooling which will also be tripped on if/when the engine approaches 120C. This also assumes an operational aircon system.

A replacement resistor should be fitted asap, though I realise that's easier said than done in the circumstances. As an emergency measure the failed resistor could be cut out and replaced using heavy gauge wire and good cable connectors. This will give high speed cooling instead of low speed, but is better than nothing. I'd also suggest knowing how to run the trip screen diagnostic mode so you can display the actual running temperature. The standard gauge is of little use to you.

The fan system is permanently live, so any such work must be done with the 80amp fuse removed in the engine bay fuse box or with the battery disconnected.

TC

[andrewinpopayan]

I back up doing exactly as T-Cut says.

[rovertone]

Thanks T-Cut
I have done that and fan comes straight on, also goes on and off respectively if I toggle between Auto & Econ. Previously I did have the engine running for quite some time, probably with aircon on, fan ran similar speed to the above test, I tried to block off the grille to induce engine to heat up but temp gauge stayed steady on normal mid-point, no fan 2nd speed cycling. Presumably my resistor is ok but still not sure how to test to see whether speed 2 is working maybe leave engine running a bit higher than tickover for a while longer or wait till the weather gets hotter out here and go on a good solo run and then let it idle.

Given that since the two episodes of overheating I have driven probably 800 miles mainly on motorway pulling the van at speeds consistently around 60mph and at times higher up some fairly long uphill gradients pulling either up to 2000 rpm in 5th or to c2500 rpm in 4th without any problem. Maybe I was just too heavy right footed on the steep climbs!

[andrewinpopayan]

Would the auto box put the engine into limp mode if the ATF was overheating, apparently the diesels have a cooling fan assembly for the ATF.

[SD1too]

I came to a very long steep climb ... when temp gauge started to rise and engine went into limp mode ..
Hello Tony. Let's try to work out what's going on.

First of all, for a diesel engine temperature gauge to rise above 'normal' is a very serious matter. It indicates that the engine is seriosuly overheating. By the way, I think you mean that the automatic gearbox went into "limp mode" or, more accurately, "EP" mode which is Emergency Program.
... could 2nd fan speed not be kicking in (it runs when a/c is switched on), is it possible to check it?
Tony; when you activate the air conditioning the slow speed should run continuously. If the fan switches on and off rhythmically, that's the second (fast) speed. So what do you get: continuous running or switching on and off?


On the diesel, the low speed should trip on at 105C or so.
Actually, it's at 100°C. Come on T-Cut, you're an old hand on the forum, you should know this by now! :D

As an emergency measure the failed resistor could be cut out and replaced using heavy gauge wire and good cable connectors.
This is not advisable since the slow speed relay is not rated for the full motor current.
Presumably my resistor is ok but still not sure how to test to see whether speed 2 is working ..
Forget speed 2 Tony. We need to be sure that the slow speed is working. Turn on the ignition with a cold engine and press the windscreen demist button. Is the radiator fan running? Also confirm that your air con. is in working order please.

Would the auto box put the engine into limp mode if the ATF was overheating ...
I have no knowledge of an engine limp mode.

Simon

[Mike Noc]

If the LP fuel pressure drops too low the ECM will put the engine into limp mode Simon.

Simple test to check is unplug the LP fuel pressure sensor - it sits on the top of the fuel filter.

Tony sorry if I'm stating the obvious, but have you checked the coolant level?

[SD1too]

... it sits on the top of the fuel filter.
Mike; I could have sworn that someone told me that the diesel doesn't have a fuel filter. :shrug:

Simon

[Mike Noc]

Ah well I did mention recently that it doesn't have a fuel filter in the tank. :D

It sits up front where it is nice and easy to access.

[rovertone]

Thanks for all the input folks.
With a cold engine if I turn on ignition and press demist the rad fan starts running and goes off when |I switch off demist. Likewise the same happens when I switch on Auto on Aircon and fan goes off when I switch to econ.

The aircon is working ok

I trawled thru the workshop manual and could only find brief reference to engine safe /limp mode, which suggested that it is triggered if either water temp/ ATF or engine oil excessively overheat but no content that I could find to say what status the engine takes.

The first time the problem happened the engine power just gradually faded, I throttled right back, noticed then that the engine temp had risen, say 4mm on needle above norm half way point. Throttling back must have lightened engine load and power picked back up, temp rose and power faded again, did this about 6 times till got over the top and everything went back to normal.

Water, as well as cooling the engine, as far as I can ascertain also cools ATF so it could have been excessive coolant temp or ATF or both which triggered limp mode which led me to ponder on 2nd speed of fan not working to cool the water to cool the ATF etc.
As I said earlier I noted that HGV's going up this first climb were crawling with hazards on from fairly near the bottom so perhaps they were used to the route and knew the load it would place on engine cooling and maybe I should have been a bit easier.
If my fan is working correctly on both speeds then unless radiator airflow is restricted it was just the severity of the workload. I am fairly certain that airflow is ok but will have a look tomorrow, the aircon condenser sitting in front of the rad never struck me as ideal arrangement anyway. Thanks again for all your input.

[SD1too]

Tony,

Your radiator fan appears to be working normally. I hesitate to say any more than that, other than wondering whether the weight of your caravan is within that permitted to be towed by your car. I feel sure that you'd have checked that. :}

Simon

[rovertone]

Simon, I reckon I am within the limits ok, kerb weight for CDti shows a range of weights, I have gone for 1585kg, the caravan is 1420kg which comes in at about 90%, ideal recommendation is 85% but the extra 5% is not excessive.
In every other way the outfit is superb, the car pulls like a train and is very stable, i consider it to be a superb towcar. I think that I am going to 'suck it and see', in a couple of months I have a 1600 mile journey back home over quite varied terrain, so will see what happens. Putting it in context i have covered 1960 miles with only these two incidents. I was just struggling to get my head round the logic of what caused the problem. Thanks again for your input. Tony

[rich17865]

Do you have a top hose thermostat mod? I have heard these can sometimes cause issues with towing.

[rovertone]

no just the bog standard set up

[rich17865]

It was worth a guess I suppose. :)

[RodgerD]

Would the auto box put the engine into limp mode if the ATF was overheating, apparently the diesels have a cooling fan assembly for the ATF.

Only early car (up to around 2001) have the oil cooler in the LH wing, later cars have a oil to water cooler. If car has fog lights then later cooler is fitted.

[andrewinpopayan]

Only early car (up to around 2001) have the oil cooler in the LH wing, later cars have a oil to water cooler. If car has fog lights then later cooler is fitted.

I am reliably informed that if the ATF does go over temperature, the IPK flashes up a message as well. So back to square 1 :duh:

[T-Cut]

Actually, it's at 100°C. Come on T-Cut, you're an old hand on the forum, you should know this by now!

I enjoy being provocative.

This is not advisable since the slow speed relay is not rated for the full motor current.

I know, but stuck in Portugal without a slow speed fan, tell us what you'd do.

TC

[SD1too]

I enjoy being provocative.
:D :D
I know, but stuck in Portugal without a slow speed fan, tell us what you'd do.
Yes, you did suggest it as an emergency measure. The problem is that such temporary modifications have a habit of becoming permanent so I thought it best to sound the warning klaxon so that everyone is aware of the risk. But I take your point; yes I would do whatever was necessary to get the fan working.

Simon

[andrewinpopayan]

:D :D

Yes, you did suggest it as an emergency measure. The problem is that such temporary modifications have a habit of becoming permanent so I thought it best to sound the warning klaxon so that everyone is aware of the risk. But I take your point; yes I would do whatever was necessary to get the fan working.

Simon


I think the OP stated that the fan was working correctly :D.
With a cold engine if I turn on ignition and press demist the rad fan starts running and goes off when |I switch off demist. Likewise the same happens when I switch on Auto on Aircon and fan goes off when I switch to econ.

The aircon is working ok
AFT fluid up to level?
So system blockage or dodgy thermostat. Time for the dishwasher tablet treatment?

Andrew

[tony2]

Had the same issue a few years back with a Jaguar XJ.
Towing to Spain all ok till I got to a long steep climb with high air temps and aircon on. Temp gauge went into the red. Never happened before.
Stopped at a service station and washed out the rad core with a hosepipe, Choked with dead insects reducing airflow, fine after.
Worth a try.....:}

[smeegol]

I recently had the overheating problem on the motorway.
temp gauge started rising.
Turned out to be my water packed up and i had a hole in the radiator that popped as the back pressure increased.
Took it to horners in salford and they replaced the water pump, thermostat housing (not needed but may as well do at same time ), radiator, alternator and power steering belts.

[rovertone]

When towing up very long climbs in hot climes the coolant overheats and engine goes into safe mode. I thought I had solved the problem when I found that the 1st speed of fan was not working so fitted a gold resistor and checked that both speeds definately work ok.
Does anyone know whether it is possible that the 2nd speed works when called for by the aircon but doesn't when a high coolant temp demands it? I tackled a 6 mile constant 5% gradient in ambient high 30's and had to stop to give the engine a breather several times as I ground to a halt.

I was running with the OBD temp display and watched the temp climb fairly quickly up to 120 deg each time. it was a bit hairy with only half a hard shoulder and wagons roaring past but I am pretty sure that the fan was only running on 1st speed! I did also notice along the journey, no gradients, that I heard the 2nd speed come on (aircon call) and the coolant temp dropped from mid 90's to high 80's. On other climbs at lower ambient I watch the temp climb and have just managed to clear the tops with 115c showing. I have not lost a drop of coolant. I can find the fan trigger settings for 3 speed fan but not 2 speed so I am not sure at what temperature I should expect the engine to operate. At tickover with aircon on in traffic and 1st fan speed temp sits at 84deg.
As background to this:-
On a 3500 mile return trip to Portugal I have had the following:-
Burst radiator (suspect my fault abt 2yrs ago spanner slipped nicked fin)
Aircon leak (spanish mechanic damaged o ring on refitting)
Fan 1st speed not working (was ok in spanish garage was roaring away)
Heater hose holed (by bleed valve? disturbed when rad fitted?)
Aircon started whistling (when o ring changed noted condensor fins failing)
Crank pulley failed (little warning centre boss broke clean away)
Belching black smoke when under load or hard acceleration ( last 2 days)

All fixed except overheating and smoking, sorry for long epistle but any help would be welcome, apart from all this the car is brilliant!
Thanks Tony

[SD1too]

Tony,

Have you got the original MGR thermostat in your diesel or have you fitted one of the in-line extra thermostats?

Simon

[rovertone]

Hi Simon,
No it's the original stat. Without the van I have never had a problem, albeit have never used the OBD to check actual temp.

[SD1too]

... it's the original stat.
OK; you say that the engine reaches an operating temperature in the high eighties/low nineties. When this happens, can you reach the long coolant pipe leading from the bottom of the radiator to the thermostat housing to feel its temperature (I'm not familiar with the diesel engine, so I'm going by the MGR diagram)? It should feel hot; almost as hot as the top radiator hose.

Towing the caravan is putting a lot more load on your engine so I would expect any latent fault to show itself.

Simon

[rovertone]

Thanks Simon,
I haven't tried that but I will. The temp I quoted was towing. Car solo, even out in the heat of Portugal,the temp driving normally ranged 79 - 84 deg.
I was surprised just how much the temperature fluctuated. In 36deg heat towing it ranged from 92 - 114 dependent on workload but then exceeded this on exceptional climbs. In France where the ambient dropped 10deg the coolant temp dropped by a similar value. The engine cooling would seem to be working ok, as soon as the engine workload drops so does the temperature. This is why I have this hunch about the 2nd speed fan not tripping in at the top end, in hindsight when I was at 120deg I wish I had shorted out the trinary switch to force the second speed to see what happened to temperature. I don't know how I can get the engine hot enough, without pulling uphill to test the theory.
I had a 160 remap by Phil T4 in March and he reported all was ok, maybe another T4 health check might be able to test fan/coolant link. Tony

[roverbarmy]

Many years ago, I used to tow with a Rover 3500 auto and had similar problems. There was an extra oil cooler available for the auto gearbox which, after fitting, cured my problems. I also found that by using the gearbox "manually" ( selecting a low gear for the climb), it seemed to allow the gearbox to run cooler, which in turn, put less strain on the engine. I also used to run the heater on hot (with all the windows open) when on long climbs in the alps. Not very comfortable for the passengers but it kept the engine temps down!
Mike

[T-Cut]

I can find the fan trigger settings for 3 speed fan but not 2 speed so I am not sure at what temperature I should expect the engine to operate.

Jules said:
For 2 speed diesel motors IIRC the ECU energises SLOW speed for a larger temp span.
From 100°C to 111°C = Slow Speed
From 112°C to 119°C = High Speed

I'd say your engine is simply responding to the high work load in a hot environment.

TC

[SD1too]

The engine cooling would seem to be working ok, as soon as the engine workload drops so does the temperature.
I would say that your cooling system isn't working properly Tony. The 114° coolant temperature is proof of that.

I suggest that you perform the trinary switch test to establish whether or not your fan is working on high speed.

A possible explanation is that your ATF is getting too hot. This should trigger the fan too when it exceeds 110°.

I had a 160 remap ...
I don't know whether it's appropriate, but have a look at this (http://www.the75andztclub.co.uk/forum/showpost.php?p=1806467&postcount=15) from someone who worked at Longbridge.

Simon

[SD1too]

Jules said:
For 2 speed diesel motors IIRC the ECU energises SLOW speed for a larger temp span.
From 100°C to 111°C = Slow Speed
From 112°C to 119°C = High Speed
Hmmm, I'm not sure about that. I've never seen documentary evidence of it, and it would require a differently programmed ECM. Besides, it makes no sense. Why would you increase the cut-in point of the fan to 111° just because it has 2 speeds rather than 3?

I wonder how Jules obtained those figures as the diesel is so difficult to get above 90°. :shrug:

Simon

[RoverDan]

(Rover 3500) There was an extra oil cooler available for the auto gearbox which, after fitting, cured my problems.

My 51 plate Connie has the extra cooler fitted (in front of NSF wheel, slatted wheel arch liner), my 52 Club and 53 Connie LWB do not. None of them has the towing pack fitted. I suspect that removal of the gearbox oil cooler was part of the cost reductions... was it still an option with the factory towing pack...?

[marinabrian]

My 51 plate Connie has the extra cooler fitted (in front of NSF wheel, slatted wheel arch liner), my 52 Club and 53 Connie LWB do not. None of them has the towing pack fitted. I suspect that removal of the gearbox oil cooler was part of the cost reductions... was it still an option with the factory towing pack...?

The gearbox oil cooler was moved to be positioned on the front of the subframe on later cars.

TBH it is in a better place altogether ;)

Brian :D

[rovertone]

My 51 plate Connie has the extra cooler fitted (in front of NSF wheel, slatted wheel arch liner), my 52 Club and 53 Connie LWB do not. None of them has the towing pack fitted. I suspect that removal of the gearbox oil cooler was part of the cost reductions... was it still an option with the factory towing pack...?

That's interesting, I think I read somewhere about a change to the gearbox oil cooler under project drive, maybe it's a smaller less efficient one. I do have some sort of cooler for gearbox . I will also try and check up on what the towing pack consisted of, maybe that will be the extra cooler you have in NSF wheel arch.

Maybe then my engine is going into safe mode due to ATF temp not coolant but it's hard to believe that it is within limits to reach 120deg.

Thanks again Tony

[rovertone]

Hmmm, I'm not sure about that. I've never seen documentary evidence of it, and it would require a differently programmed ECM. Besides, it makes no sense. Why would you increase the cut-in point of the fan to 111° just because it has 2 speeds rather than 3?

I wonder how Jules obtained those figures as the diesel is so difficult to get above 90°. :shrug:

Simon
I cannot find anything either, I will probably be in touch with Jules at some stage, although the condenser is not totally shot its on its way so will be replacing. Just want to get clear in my mind what needs doing before I strip the front off again. I'll test the fan again later. Thanks

[SD1too]

.. maybe that will be the extra cooler you have in NSF wheel arch.
It wasn't an extra cooler Tony. The location was changed (NSF wheel arch to front of engine bay) and so was the cooling medium (air to engine coolant).
... it's hard to believe that it is within limits to reach 120deg.
You're right, it isn't "within limits" for the engine coolant to reach 120°.

I've suggested some action you can take Tony. I hope that you will.

Simon

[Greeners]

Check the fan is working on both speeds, although the first speed should be ample to keep the temperature down.

Change the gear box oil as well, as it may well be burnt now the engines got that hot under load

[rovertone]

My cooler is definately bottom front of the engine bay, thanks for clarifying. I will certainly follow through your suggestions, once I've cleared out the crud of the journey from car and caravan. Hoping to do the trip again in a couple of months but only if I am certain the problem is sorted. I'll let you know what I find.
Thanks again.
Tony

[rovertone]

Check the fan is working on both speeds, although the first speed should be ample to keep the temperature down.

Change the gear box oil as well, as it may well be burnt now the engines got that hot under load

Thanks, I changed it not long before my trip but thought it wise to again given the beating its been taking!

[T-Cut]

I wonder how Jules obtained those figures as the diesel is so difficult to get above 90°.

No idea, I just reported all I could find on the question. Maybe someone should do the experiment. I clearly needs doing.

A diesel pulling a caravan uphill in a 35C ambient will do it.

TC

[rovertone]

It wasn't an extra cooler Tony. The location was changed (NSF wheel arch to front of engine bay) and so was the cooling medium (air to engine coolant).

You're right, it isn't "within limits" for the engine coolant to reach 120°.

I've suggested some action you can take Tony. I hope that you will.

Simon

Simon,
I took car (solo) for a test run of about 25 miles, mainly dual carriageway mixed with local roads. Ambient temp 16.5c Aircon off (i.e. no fan).
OBD temp readout was in the range 77 - 84 but generally 79/80. Top end when pulling up gradient, bottom end negligible throttle down gradient.

I then ran the engine at idle for 1 hour and it reached 95c raising the revs for last few minutes I managed to get the temp to 97c at which point the 1st speed fan kicked in and quickly reduced temp back to 94c when fan switched off.

I could not get to the hose off the water pump but at 84c the top hose was too hot to grip, the bottom hose off the rad was very warm but could just grip it, barely able to at higher temp.

I did not need to do the trinary switch test to check the fan, at the start of the idle test at 84c I switched on the aircon to kick in the slow fan, temperature immediately started dropping but then the high speed fan kicked in and temp quickly dropped to 79c. Clearly there is a problem with the aircon condensor, I tried it several times and the high pressure pipe went from mildly warm to very hot very quickly (15 secs) although aircon has worked well for 1700 miles so its maybe surprising that the high speed fan hasn't been on 100% to keep it cool!

To me this sounds like all working ok, just wish I could get temp up higher to test high speed fan operation at coolant trip point.
Any thoughts. Thanks Tony

[pm77]

I wonder how Jules obtained those figures as the diesel is so difficult to get above 90°. :shrug:

Simon

One way is a fubared fan and a massive air lock in the coolant system, so I've found out:o:eek:

[SD1too]

To me this sounds like all working ok ..
:iagree:
... just wish I could get temp up higher to test high speed fan operation at coolant trip point.
Good point, because on the diesel the trinary switch request for a higher fan speed goes directly to the electronics in the fan control box. Speed control for coolant comes from the ECM.

One way you could do it is to substitute a low value resistor for the coolant temperature sender. 580Ω would tell the ECM that the coolant was at 120° which, being higher than 112° should trigger the fast fan speed. :D

Simon

[rovertone]

Hi Simon,
Hmmm substitute resistors is stretching my expertise .............

I have ordered a new condenser from Jules and was talking with him about his Retrovec fan conversion in context of the problems I am having and interestingly he said that on an 03 reg my original fan must have been a 3 speed so the 2 speed I now have must have been a replacement. If this is the case it begs the question was it wired correctly?
I have tried again fast running the engine with cardboard down the radiator (eng side) and a blanket over the front but cannot get temp over 97c, the fan slow speed comes on and down it goes again!
Jules did suggest that a T4 could simulate a coolant temp of 112c which would test the fan. There was a guy near me TS Autos in Stourbridge who had one but I can't seem to find a contact. If not I'll probably give Phil-T4 a shout.
Thanks again for your thoughts, I'll not let it beat me but it's grinding a bit! Tony

[T-Cut]

Couldn't you simply disconnect the coolant sensor? That should invoke high speed cooling.

TC

[Union Wheels]

Hi rovertone,
having just read through this thread, and all your problems in the first post, I was wondering if any radiator sealant (radweld, K-seal) or the like had been added when you first had the radiator leak.

If so this would account for all your problems as it seems to me the radiator has lost its efficiency

The black smoke you mention is unburnt diesel and is normally associated with leaking O rings at the inter-cooler or a loose turbo boost pipe.

[SD1too]

Hmmm substitute resistors is stretching my expertise .............
OK. T-Cut has come up with the easiest solution; just disconnect the sender temporarily.
... so the 2 speed I now have must have been a replacement. If this is the case it begs the question was it wired correctly?
2 speed MG Rover replacement fan systems are fully compatible with 3 speed installations. It's just a matter of plugging it in. No wiring is necessary.

Simon

[rovertone]

Hi rovertone,
having just read through this thread, and all your problems in the first post, I was wondering if any radiator sealant (radweld, K-seal) or the like had been added when you first had the radiator leak.

If so this would account for all your problems as it seems to me the radiator has lost its efficiency

The black smoke you mention is unburnt diesel and is normally associated with leaking O rings at the inter-cooler or a loose turbo boost pipe.

Hi UnionWheels,
Yes I added a radleak product when the radiator burst, it didnt touch it, the spanish garage tried the same with something similar same outcome which led to new radiator being fitted. With the rad out I assumed most of the residue would have vacated, it is my intention to flush the system anyway as Ihave to strip down to replace the condenser.
The intercooler seals and hose look ok but I have new viton ones 'in stock' ready to fit. Once Ican get to the bottom of this overheating I intend to go through everything, even thought of fitting new water pump and stat. I am concerned what deterioration may have occurred elswhere with this overheating.

T-Cut Thanks so simple, will try it tomorrow.

Thanks for all your input

[rovertone]

Disconnected ECT sender and cooling fan runs 1st Speed. As a 'sanity' check whilst it was running I shorted across the trinary switch and the 2nd speed kicked in ok.
So still left with the question as to whether the 2nd speed kicks in ok driven by the ECT sensor. It all points to the fact all should be fine but I am certain that it wasn't doing so when I ground to a halt at 120deg.
I just wish it had been safer for me to have been able to short the trinary at the time and spend more time investigating.
Next step must be to see if a T4 can simulate an overheat situation?

[T-Cut]

Disconnected ECT sender and cooling fan runs 1st Speed.

It should invoke emergency high speed cooling.

TC

[Greeners]

I'm pretty certain the T4 can instruct the ECU to run the fan at both speeds on demand

[rovertone]

It should invoke emergency high speed cooling.

TC
Thanks, this does seem to be where my problem lies.
Another thought that occurred to me is the fact that when the gauge starts to climb into the 110c region it keeps on going, you would expect that when/if the high speed fan kicked in at say 112c there would (and should) be a reduction or a pause in the temp rise the same as 1st speed at lower temps.
Hoping this isn't a problem with the ECM!

[T-Cut]

I doubt it's an ECM/ECU issue. The temperature will fall when heat removal by the cooling system is greater than heat generation by the engine. Caravan towing puts any engine under stress, so heat levels rise as more fuel is being burnt at any particular speed. You might find that heat loss improves by reducing speed and dropping down a gear for a short period. This increases coolant flow through the engine and radiator. Radiator heat exchange rate depends primarily on the temperature difference between coolant and ambient air. It has a greater effect on cooling than the air speed, so towing when ambient air is 35C is going to reduce heat loss by a lot. When things start getting warm, say above 110C, additional loss can be had by putting the internal heater to max with aircon off. Not very comfortable for the car occupants, but it will reduce engine load and the coolant temperature significantly.

TC

[rovertone]

TC Thanks
I tried to keep the engine rpm at 2500 +/_ 500 range in what ever gear to keep the engine comfortable. From what you say maybe a slightly higher engine speed could be more beneficial to move the water faster. Interestingly on motorway cruising I found that the temp was lower running in 4th at 2500rpm than 5th at 2000.
On the climbs I did have the heater going full belt which must have helped.

I found even in northern France on less severe motorway climbs I was 'holding my breath' watching temp getting up towards 110c, other cars with vans seemed to be coping ok. My van loaded weighs in at 1460kg so is well within its limits. I would be very sad to have to part with the car in favour of a larger engined 4x4, we want to do this same trip on a regular basis and confidence is low right now.

[SD1too]

Yes I added a radleak product ... the Spanish garage tried the same with something similar ...
I think this is the root cause of your problems Tony. :o

Simon

[rovertone]

Simon,
I have a Condenser on order so will be stripping down again and was planning to remove rad, put a hose thru it and thru heater hoses etc. with gentle pressure to clear any crud that may be in there, presumably this stuff only hardens where it makes contact with air. Be good to catch the coolant that came out to see if anything was in there.

I would like to think that the spanish garage flushed the system thru but I think that is a bit optimistic!

I am thinking that my black smoke maybe also be due to the way they refitted the intercooler O rings if the state of the aircon O ring is anything to go by!
Tony

[T-Cut]

Without the caravan in tow, the engine runs like they all do, at around 80C, even in the 35C ambient. Without the extra load there's nothing unusual about the running temperature. Double the car's mass with the caravan, haul it all slowly uphill and it gets hot. I'm pretty confident all the other cars pulling caravans are equally hot.

My van loaded weighs in at 1460kg so is well within its limits.

The limit is 1600kg, which also includes passengers and any cab/rack luggage, so maybe closer than you thought.

TC

[rovertone]

Just wondering whether anyone has experienced overheating when towing up long climbs.
I had problems earlier this year in Spain, the only thing I found when I got home was condenser in poor condition causing aircon system to overheat. Solo driving the cooling system works fine, too cool in fact (80c), rad (new), hoses, fan have all been checked and are fine, no leaks.

I have been reading that some vehicles do have problems with hills in warm climes as engine bay gets hot and heat cannot dissipate quickly enough under such extremes but I have not found anything specific re R75.
I plan another trip so may have to 'suck it and see' as to whether the problem is solved, albeit the only other thing i might try is to have a session on a rolling road where it may be possible to load the engine to try and replicate a similar. Be interested to hear if anyone else has experienced similar. Thanks

[macafee2]

what speed were you travelling at, what revs and how steep was the hill?

macafee2

[spyder]

What temperatures are you looking at ? If the fans are working correctly the slow and then high speed fans should keep it well with-in limits of over-heating. Getting very hot is normal for most cars towing up hills though-just as long as it comes down when conditions change.

Craig.



Just wondering whether anyone has experienced overheating when towing up long climbs.
I had problems earlier this year in Spain, the only thing I found when I got home was condenser in poor condition causing aircon system to overheat. Solo driving the cooling system works fine, too cool in fact (80c), rad (new), hoses, fan have all been checked and are fine, no leaks.

I have been reading that some vehicles do have problems with hills in warm climes as engine bay gets hot and heat cannot dissipate quickly enough under such extremes but I have not found anything specific re R75.
I plan another trip so may have to 'suck it and see' as to whether the problem is solved, albeit the only other thing i might try is to have a session on a rolling road where it may be possible to load the engine to try and replicate a similar. Be interested to hear if anyone else has experienced similar. Thanks

[rovertone]

These were long hills c 3/4 miles constant 5% . Ambient temp in 30's

On the last climb, monitoring temp on OBD it rose to 119/120 with engine cutting back to 'safe mode' at about 117c, after a short while at tickover temp dropped back (still 100+) but with power resumed was able to continue but took several cycles to get over the tops.
I had problem on 3 climbs in total but it was only on the last one that i was using OBD read out, the previous ones the gauge was showing normal (mid way) by the time it started to rise above that it was too late and engine safe mode was activated. A few other hills saw temp up to 115c but at point where I had reached top so stopped holding my breath!

On normal terrain I found that driving in 4th (auto) was best around 2/2.5k rpm. When coming to the hills I tried to keep engine in 2.5-3k rpm in D2.

As soon as hills were topped temp dropped back into high 80's/90's. On the last climb when I first stopped, it was a bit hairy because there was no hard shoulder and traffic was roaring past but I did get out to check the fan and I am sure at 118 c it was only on 1st speed, I only had a quick look, it was difficult because of the noise of the traffic and the position.

I have since tested the fan, via the demist/trinary switch and both speeds work fine. I have managed to get coolant temp to 97c at fast tickover with rad/grille covered and 1st speed kicks in and temp immediately drops back. I have had a T4 simulate a signal to the fan from ECM (i.e coolant sensor signal) and both speeds work fine. I am at a loss, hence my hunch re rolling road to get temp higher. I just regret not spending more time at the road side to be sure about fan speed. At some stage my fan has been changed from 3 speed to 2 speed and can only assume that it was done correctly via a plug and play conversion.

[James.uk]

>>>On normal terrain I found that driving in 4th (auto) was best around 2/2.5k rpm.<<<

Why did you select 4th instead of "D" (drive) ??? had the car changed up into 5th the revs would have dropped and that would have helped keep the engine temp down??? :shrug:
...

[rovertone]

Two things really, in D the engine wasn't 'comfortable' when speed dropped to 1700 ish rpm so was better to let it drop down but as it was frequently doing this it was easier to leave it in D4.
Secondly, interestingly the temp ran slightly cooler at 2-2500rpm in 4th than at 1700/2000rpm in 5th. I presumed that with the engine close to labouring it was working harder therefore hotter whereas at higher revs the coolant and exhaust gases flowing faster thus moving heat away faster. That was just my hunch!

[James.uk]

Well if it worked it was a good plan innit.. :}

Have you had the car remapped at all? for towing a 160 remap should help.... :}
...

[rovertone]

Yes had 160 remap. Car is first class towing, very stable and plenty of power, that's why I am determined to try and get to the bottom of this problem. Don't want to have to swap to a 4x4!

[spyder]

I tend to tow in sport mode, also a 160, and it seems to prefer that on hills and twisty roads.
The highest I have ever seen climbing a hill in the highlands with lots of traffic, is 105 degrees-also holding my breath.

Has your car got an inline stat ?
When last did you change the coolant, what colour was it ?
Water pump ? I have heard of a new one that had sheared.

Craig.

[rovertone]

Thanks, I will try sport mode next time I'm out.

No inline stat fitted, I understand it's not advised when towing. Given the solo running temp of 79/81 I am reckonning the stat is opening too early and needs replacing but given the overheat prob i am leaving it for now.

Coolant is red OAT and was renewed at the same time the condenser was replaced.
I understand that the fan 2nd speed is triggered at 112c but I can't get the engine hot enough to test for sure. When the temp started rising when climbing, just as my test at 97c with 1st speed, you would expect the temp rise to have stopped or slowed down as it passed thru 112c but it didn't it just kept on rising. I cannot grasp how all the tests show the fan to work ok for it not to work when triggered by actual high coolant temp!

[Jules]

What cooling fan is fitted?
3 speed, 2 speed or after market?

Get a T4 session to test the fan fully on all speeds ;)

Did you try it with AC off?
If condenser is past it's best (90k miles) it will super heat the rad behind it !!



Jules

[TR75]

I have had the same problem most recently when towing. Coming back through Cornwall and stuck in traffic. Stop start all the time and noticed the needle steadily rising from the 9 o'clock position. Straight away I turned the heater on and all the fans and it died back down.

Got home, tested the fan with the AC on and nothing. I have no resistor behind the fan so have an earlier type being an early 2001, but Have no idea where to go next... need to rectify it ASAP and as cheaply as possible.

[Jules]

New fan £269 (inc fitting.)
Or £139 mail order :smilie_re:

Revotec cooling kit
http://www.the75andztclub.co.uk/forum/showthread.php?t=189409


Jules whole forum shop index
http://www.the75andztclub.co.uk/forum/forumdisplay.php?f=74


The older 3 speed fans fail as early as 60k miles
Good luck


Jules

[rovertone]

Car has a 2 speed fan fitted as its an 03 reg I understand that this would have been changed from its original 3 speed but i have no history on this.

The fan tests out fine on both speeds on the demist/trinary test, and have had it tested on a T4 which again tested ok.

As I have been sure all along that the second speed wasn't working when I overheated, the only way i thought that I had any chance of getting temp to 112deg to test it would be on a rolling road dyno.

I had a session today and it worked and I got the proof. At 115deg with temp gauge moving off 'normal' and fan on 1st speed only. This was done several times without any auxillary test bed fan.
Next test using a 'medium' velocity fan and albeit rising more slowly the engine overheated.
The final test was with a very high velocity fan (reputed = 100mph) and whilst getting up to about 110deg it was very slow to get there, that was with the bonnet open, amazingly there was a big difference when we closed the bonnet, reaching about 105deg. I am not sure what the air speed velocity of 2nd stage is compared to the test bed but i think i am convinced enough that i have found the problem.
But given the positive fan tests how do i find out why the coolant temp doesn't trigger 2nd speed? Control box wiring error when the fan was upgraded?
Jules does your Revotec conversion override my existing control box?

Pleasingly as a side issue the power run recorded 126.95bhp at the wheels so near as dammit 160 at the engine (Thanks Phil T4)
Thoughts from any electronics experts out there would be most welcome. I'm stumped!
Thanks Tony

[Jules]

Evening Tony


I was going to suggest the high speed perhaps isn't high enough.
Possible someone has fitted a 2 speed from a 1.8 ?? (only 350W instead of 450W)

Or possibly some Chinese copy which don't produce the same power as OEM.

The Revotec kit uses existing control box to retain the full intelligence of your ECU control.

I will supply you one on sale or return if you like and you can try it out.;)
No Caravanner has complained of lack of cooling yet with our kit on.
We did choose the most powerful motor Revotec have on their list of 3 for this very reason.

[rovertone]

Hello Jules,
I'm not sure what's happened to the thread, its not on the forum! I only found this by searching under my username.

Thanks for that offer, I may well take you up on that. I would like to try get a steer on why the signal to run is not getting to the fan itself. On the basis of what's happening at the moment no fan would work. I have even wondered whether to break into the trinary circuit and put a simple toggle switch to flick the 2nd speed on when i encounter exceptional hills but that is not my style I would like to fix it correctly.
Thanks again for the offer i will get back to you.
Regards Tony

[rovertone]

Sorry found thread, I had forgotten that I had posed question under 'towing.... as well as technical. Senior moments and all that..

I'll add to that thread as well, probably a wider audience for thoughts
T

[RayH]

At 115deg with temp gauge moving off 'normal' and fan on 1st speed only.

But given the positive fan tests how do i find out why the coolant temp doesn't trigger 2nd speed? Control box wiring error when the fan was upgraded?

Jules does your Revotec conversion override my existing control box?



The Revotec kit uses existing control box to retain the full intelligence of your ECU control.

I will supply you one on sale or return if you like and you can try it out.;)


That probably isn't going to help Jules, if the high speed isn't being triggered on the existing fan :shrug:

If the trinary test triggers it and a T4 can trigger it then surely the only thing left is an out of spec temp sender or dodgy connections to it? :shrug:

[Jules]

Sorry missed that bit !!
Does the trinary test operate the High speed?


Jules

[RayH]

Sorry missed that bit !!
Does the trinary test operate the High speed?


Jules

Yes post #4

[Jules]

That is a very strange fault.
Sounds like temp sender is working correctly because gauge is registering correctly.

The T4 I assume changes the pulse width of the PWM from 25% to 70% approx (not proved that on a scope but I will soon)

Seems PWM is working as it responds to T4 forced outputs. :shrug:


But like I've said before these PWM boards are weird.
One will work in one car but not another almost as though there is a "electronic tolerance" issue.

[rovertone]

Getting closer!
The fan works on both speeds using the demist/trinary test. Also works ok when triggered from T4.

As I have been sure all along that the second speed wasn't working when I overheated, the only way i thought that I had any chance of getting temp to 112deg to test it would be on a rolling road dyno.

I had a session today and I got the proof! At 115deg with temp gauge moving off 'normal' the fan was on 1st speed only. This was done several times without any auxillary test bed fan.
Next test using a 'medium' velocity fan and albeit rising more slowly the engine still started to overheat.
The final test was with a very high velocity fan (reputed = 100mph) and whilst getting up to about 110deg it was very slow to get there, that was with the bonnet open, amazingly there was a big difference when we closed the bonnet, reaching about 105deg. I am not sure what the air speed velocity of car 2nd stage fan is compared to the test bed but i think i am convinced enough that i have found the source of the problem.
But given the positive fan tests how do i find out why the coolant temp doesn't trigger 2nd speed? Control box wiring error when the fan was upgraded? How can I test without going back to the rollers?

Pleasingly as a side issue the power run recorded 126.95bhp at the wheels so near as dammit nearly 160 at the engine (Thanks Phil T4)
Thoughts from any electronics experts out there would be most welcome. I'm stumped!
Thanks Tony

[RayH]

That is a very strange fault.
Sounds like temp sender is working correctly because gauge is registering correctly.

Ah! That's true if OBD reading come off the same sender.
Strange indeed!

Tony - what happens if you disconnect the plug from the temp sender?

[rovertone]

Given that the OBD readout seems accurate as in a fast idling test I was able to get the temp to 97deg which correctly triggered 1st speed ok.
Also given that if the 'normal' position on the gauge represents the range 75 - 115deg when the OBD readout starts to rise above this the gauge follows suit.
I can only presume that the sender is giving out the right signals unless there is any separate wiring/signal connection to the fan that is different to that picked up by the OBG/Gauge.

Ah! That's true if OBD reading come off the same sender.
Strange indeed!

Tony - what happens if you disconnect the plug from the temp sender?

Fan runs 1st speed, advised to test that a while back as it was suggested that this should default to 'high' fan speed but Rover manual only states that in the event of sensor failure ECM assumes a temp of 80deg and provides fan cooling as a safety measure.

[SD1too]

... i thought that I had any chance of getting temp to 112deg to test it would be on a rolling road dyno.
I had a session today and I got the proof! At 115deg with temp gauge moving off 'normal' the fan was on 1st speed only.
Tony,

How on earth did you get your diesel engine to reach 115° with the slow speed fan running? :shrug: :confused:

Simon

[rovertone]

Hi Simon
Dyno technician simulated engine load by putting a loading on the rollers to force the engine to work hard to drive them round, it is some form of retard mechanism on the rollers.
This guy does development work for vehicle manufacturers including the people down the road at Longbridge so apparently it is quite normal when testing for torque etc. albeit usually he has an auxillary fan going at all times to shift the heat away rather than let the engine heat up.
I guess in a similar situation when climbing, if my fan was working correctly I would still see the engine temp rise to 112deg before the high speed kicked in as opposed to the last test we did where there was high air velocity from start point which held the temp down. It is unknown whether in the scenario of correct fan operation it would move temp back down from 112deg OK, if not then I would have to accept there is a limit to towing with the car. When I tested the slow speed tripping in at 97deg on no load, the temp dropped immediately. Given the setting point is 112deg presumably Rover would have known it was possible to reach that temp otherwise why set so high.
I am really stumped, I have a guy 250 mtrs from me that specialises in 2nd hand Rover spares, the only thing I can think of is to try and see if he has a later 2 speed fan complete with matching control box (that's if I can tell if it's all original!). Tony

[T-Cut]

It's an interesting situation.


The fan works on both speeds using the demist/trinary test. Also works ok when triggered from T4.

Are you sure the speeds were different ('low' and ''high')? If the system was modified, it may be running at one speed whatever the temperature.

All the engines have an excess of cooling capacity under normal conditions. Heavy trailers, pulling uphill is pushing the system towards the limit, but won't be exceed it if the towing specs are followed. One has to wonder therefore why your system appears to be under-rated even with the application of independent fan cooling. It might be worth thinking about trying another radiator.

TC

[RayH]

Fan runs 1st speed, advised to test that a while back as it was suggested that this should default to 'high' fan speed but Rover manual only states that in the event of sensor failure ECM assumes a temp of 80deg and provides fan cooling as a safety measure.

Interesting, as with my 2004 Contemporary CDTi removing the connector brought about high speed fan rotation.

Is this the original fan or has it been changed? I really can't remember now :duh:

Ignore that, I found it in the other thread!

[RayH]

It's an interesting situation.



It might be worth thinking about trying another radiator.

TC

But that doesn't address the issue of high speed not cutting in though :shrug:

[RayH]

I'm wondering if the two speed fan has been wired up to the wrong relay in the control box?

Could this account for it operating when T4 simulated and trinary test but not on temperature rise as the medium speed relay is energised but the fan is connected to the high speed relay.

Looking at the temperatures Tony has quoted even that should have operated by then, but we would only be a couple of degrees away.

[SD1too]

I guess in a similar situation when climbing, if my fan was working correctly I would still see the engine temp rise to 112deg before the high speed kicked in ...
I don't agree Tony. When your engine is under heavy load the coolant will first reach 100° when the slow speed fan will start. That is sufficient to reduce the temperature to 98° or thereabouts provided that the cooling system is mechanically sound. You admitted earlier that sealing additives have been added on two occasions and I said that this was most likely the root cause of your problems. I suspect that your thermostat is unable to open properly due to the gunge attempting to "seal" it. You may also have an air lock if the people who have worked on your car haven't followed the bleeding process properly when refilling.

You say that T4 triggers both speeds satisfactorily. There is therefore nothing wrong with your fan control system. Be aware though that on 2 speed systems the slow speed can sound very loud indeed. Some members have been fooled into thinking that they're hearing the high speed.

Simon

[rovertone]

[QUOTE=RayH;2076459]I'm wondering if the two speed fan has been wired up to the wrong relay in the control box?

I am wondering if something has been wired incorrectly when the fan was swapped to a 2 speed hence my thinking to try and find a complete fan set up from a Mk 2.
From your threads you are clearly more versed than I on electrical matters, what would your thoughts be on, failing all other, bridging the trinary wiring with a switch to 'short' the 2nd speed into action on the very rare occasions that I would seem to need it?

[T-Cut]

But that doesn't address the issue of high speed not cutting in though :shrug:

Not directly, but my other question was did the trinary/demist/T4 tests clearly show two different speeds?

In any case, the fan speed is irrelevant when insufficient cooling is provided by the radiator when the engine's under heavy load. Your independent fan tests showed that.

TC

[rovertone]

I don't agree Tony. When your engine is under heavy load the coolant will first reach 100° when the slow speed fan will start. That is sufficient to reduce the temperature to 98° or thereabouts provided that the cooling system is mechanically sound. You admitted earlier that sealing additives have been added on two occasions and I said that this was most likely the root cause of your problems. I suspect that your thermostat is unable to open properly due to the gunge attempting to "seal" it. You may also have an air lock if the people who have worked on your car haven't followed the bleeding process properly when refilling.

You say that T4 triggers both speeds satisfactorily. There is therefore nothing wrong with your fan control system. Be aware though that on 2 speed systems the slow speed can sound very loud indeed. Some members have been fooled into thinking that they're hearing the high speed.

Simon
Under no load conditions I have proved that at 97deg the 1st speed pulls temp down immediately. With the engine under sustained load the fan would trigger at 97 (proven on the dyno) but I assume produces insufficent cooling to hold/reduce temp under continued load so temp would continue to rise to 112deg point where extra air volume is applied.
With the high velocity fan blowing on the dyno the temp held at 105 deg which sort of proves the cooling system.
The engine runs too cool solo (79/81) so suspect i need a new stat anyway. I do acknowledge what you are saying about the gunge and if/when I sort the fan running I will replace the stat and maybe the pump. The gunge was in for a very short period only, the second lot didn't even get out of the garage.

I have flushed out again and am confident there are no airlocks.

On my way home on occasions I heard the high speed fan come on which I subsequently discovered was aircon overheating so have replaced condenser (probably disturbance when rad was changed), damaged fins had caused slight blockage which I was hoping may have been my problem.

I'll do the trinary test again for my own sanity check but the speed difference is really noticable hence my hunch all along that when I had overheated even with traffic noise I should have clearly heard the fan roaring.
I am thinking that I should have a look at the fan control box wiring and see if that throws up any clues.

Very grateful for your input. Tony

[RayH]

I am wondering if something has been wired incorrectly when the fan was swapped to a 2 speed hence my thinking to try and find a complete fan set up from a Mk 2.
From your threads you are clearly more versed than I on electrical matters, what would your thoughts be on, failing all other, bridging the trinary wiring with a switch to 'short' the 2nd speed into action on the very rare occasions that I would seem to need it?

A complete "kit" as it were may well solve the problem, but if that is the case I'm sure we can solve the problem with what you have. Obviously that will largely depend on your need for the car.

My thoughts on the switch: Yes it would work but it's a bodge, I'd rather you corrected the problem rather than employ a workaround. :}

Not directly, but my other question was did the trinary/demist/T4 tests clearly show two different speeds?

In any case, the fan speed is irrelevant when insufficient cooling is provided by the radiator when the engine's under heavy load. Your independent fan tests showed that.

TC

I think it was established earlier on that two distinct speeds were noted.

I can't agree that fan speed is irrelevant as it forms an essential part of the cooling system.


I am thinking that I should have a look at the fan control box wiring and see if that throws up any clues.


I'm thinking that would be a good next step, along with a few pictures perhaps?

[rovertone]

Will do, probably over weekend sometime.
Thanks

[rovertone]

Sorry Ray, I, inadvertently by my own doing, got this thread on the Towing Forum into technical matters. At the onset i just wanted to pose the question to see if anyone else had similar problems.
To avoid confusion I will park this thread and stay with the Technical Forum going forward.
Tony

[RayH]

Sorry Ray, I, inadvertently by my own doing, got this thread on the Towing Forum into technical matters. At the onset i just wanted to pose the question to see if anyone else had similar problems.
To avoid confusion I will park this thread and stay with the Technical Forum going forward.
Tony

No problem, I just forgot which one I was in :D

[T-Cut]

I can't agree that fan speed is irrelevant as it forms an essential part of the cooling system.

We're clearly on different wavelengths so I'll not comment further.

TC

[RayH]

We're clearly on different wavelengths so I'll not comment further.

TC

Sorry TC, it wasn't a dig, your input is always appreciated.
I just couldn't see where you were coming from with that.

Ray

[Jules]

Hmmm, I'm not sure about that. I've never seen documentary evidence of it, and it would require a differently programmed ECM. Besides, it makes no sense. Why would you increase the cut-in point of the fan to 111° just because it has 2 speeds rather than 3?

I wonder how Jules obtained those figures as the diesel is so difficult to get above 90°. :shrug:

Simon


Jeez that was years ago!!! (I got them from Keith's article of Fan operation IRRC)
He got them from RCL 0311ENG which is full of mistakes!

My figures for diesel are more like:
From 100 Deg C to 106 Deg C = Slow Speed
From 106 Deg C to 119 Deg C = High Speed

In other words the high speed comes in a few degrees sooner and covers a wider temp range than old 3 speed.

[T-Cut]

My figures for diesel are more like:
From 100 Deg C to 106 Deg C = Slow Speed
From 106 Deg C to 119 Deg C = High Speed

So does this mean the low speed first trips on at 106C and then off when it's cooled to 100C - and the same principle for high speed?

Sorry to appear dim, but 'from 100C to 106C' is heating up, whereas from 106C to 100C is cooling down, which I assume is what happens.

The high speed (presumably) changes to low speed at 106C on the cooling down curve?

TC

[rovertone]

My Slow speed comes on at 97deg and is off again by 95deg which on my test was fairly rapid. ( tested several times).
I am not sure now where I got 112deg fig from for the High speed but it perhaps makes sense that it should be lower to give increased air volume chance to do its job at the higher temp.

I wonder what specs the BMW fan is set at for these engines?

[Jules]

So does this mean the low speed first trips on at 106C and then off when it's cooled to 100C - and the same principle for high speed?

Sorry to appear dim, but 'from 100C to 106C' is heating up, whereas from 106C to 100C is cooling down, which I assume is what happens.

The high speed (presumably) changes to low speed at 106C on the cooling down curve?

TC


No
Low speed on at 99- 100
Off at 95-96

Low speed stays on up to 105-106 when high speed takes over.
IRRC

[Dragrad]

Threads merged as they are related. ;)

[T-Cut]

Sorry TC, it wasn't a dig, your input is always appreciated. I just couldn't see where you were coming from with that.

That's OK. What I meant is the cooling systen isn't working whatever fan speed is running. The independent '100mph' fan blast didn't cool the engine under load. That suggests to me that the high/low speed question is irrelevent to the overheating issue. There's simply not enough cooling capacity. Logically, coolant flow (through the radiator) is too low, hence the suggestion to replace the radiator. Clearly the hi/lo fan issue is separate.

TC

[DerekS]

I noticed that whenever towing in foreign parts up long inclines and passes , the wind was always behind me . And usually , as you found , there were large heavy lorries going slowly. Meaning that there was no ( or very little) ram effect air through the radiator to cool it down . It never occured to me that the rad fan would not be working ( couldnt have heard it anyway due to engine noise ) but that might have happened in your case .

[rovertone]

That's OK. What I meant is the cooling systen isn't working whatever fan speed is running. The independent '100mph' fan blast didn't cool the engine under load. That suggests to me that the high/low speed question is irrelevent to the overheating issue. There's simply not enough cooling capacity. Logically, coolant flow (through the radiator) is too low, hence the suggestion to replace the radiator. Clearly the hi/lo fan issue is separate.

TC
Hi T-Cut,
Just to clarify, by using the high velocity fan on the dyno test the temperature held at 105deg and it was much slower getting there, whereas without it and for a similar duration run the temp was heading off the scale. This suggests that the cooling system is working ok when there is more fan power.
I am not sure whether it would have increased beyond 105 if the run had been longer but the difference was so noticeable that it was clear that the problem lay with the fan.

I guess that if I can solve that problem and I still have a overheating problem then i must question whether the car is capable of towing in such exceptional conditions and/or there is a cooling system problem. I am still 'kicking myself' that when I was overheating I didn't short out the trinary switch to force the 2nd speed which would have given me the answer........benefit of hindsight.
Thanks for your input.
Tony

[SD1too]

... by using the high velocity fan on the dyno test the temperature held at 105deg ... This suggests that the cooling system is working ok ....
No it doesn't Tony. Your cooling system should not require a high velocity fan and it should be capable of maintaining a temperature way below 105° with the slow speed fan operating.

When the temperature rises above 100° grasp the bottom radiator hose. Does it feel hot or cool?

Simon

[RayH]

No it doesn't Tony. Your cooling system should not require a high velocity fan and it should be capable of maintaining a temperature way below 105° with the slow speed fan operating.

Simon

Even when under heavy load? Real or simulated.

Leaving that aside for a moment, I was giving some more thought to the fan speed issue.

If the information here (http://www.the75andztclub.co.uk/forum/showpost.php?p=13169&postcount=2) has not been disputed then for a 3 speed setup cut-in temps are:

Low 100-105
Med 106-111
High 112-119

So when the fan was replaced with a 2 speed I suspect the low and high speed relays were used rather than low and medium.

Given the information above it is quite possible that 115 can be reached without activating the high speed relay and therefore the higher fan speed.
It would explain why demist and trinary tests work normally but there is no additional cooling at higher engine temperature.

Tony - if that is the case you will simply need to rewire to the other relay, but let's see what you have in there first.

[SD1too]

If the information here (http://www.the75andztclub.co.uk/forum/showpost.php?p=13169&postcount=2) has not been disputed then for a 3 speed setup cut-in temps are:

Low 100-105
Med 106-111
High 112-119
Ray,

That post from Keith dates from 2006 and we know more now.

The way you have expressed the temperatures above is incorrect. I believe that they have come from the MGR 'Electrical Library' section of RAVE and are unreliable. There is only one nominal cut-in temperature for each speed and for the three speed fan they are (according to the main RAVE text):

Low 100°
Medium 106°
High 112°

The cut-out temperatures are, of course, lower than these figures.

For the two speed diesel fan there may be a slight variation from these low and high speed cut-in points due to different component values on the control box PCB (source: French Mike's investigation).

Simon

[rovertone]

No it doesn't Tony. Your cooling system should not require a high velocity fan and it should be capable of maintaining a temperature way below 105° with the slow speed fan operating.

When the temperature rises above 100° grasp the bottom radiator hose. Does it feel hot or cool?

Simon

I am not sure I follow that logic Simon, why then do we need a higher fan speed(s) at all. I agree with what you say when it comes to light loads, as I proved on the fast idle test as I couldn't get the temp to rise above 97, as soon as I hit that mark 1st speed stopped it rising further, hence the trip to the dyno.

I think a good starting point is as Ray suggests, having a look inside the control box I'll do that and get back with my findings.

[T-Cut]

Just to clarify, by using the high velocity fan on the dyno test the temperature held at 105deg and it was much slower getting there, whereas without it and for a similar duration run the temp was heading off the scale. This suggests that the cooling system is working ok when there is more fan power.

An unknown factor in the dyno tests is how hard the engine was having to work. It may have exceeded the ability of the cooling system to maintain the correct temperature. Perhaps the dyno loading exceeded what the car is designed to accomodate. Undr such conditions, no fan speed would cool it. Even so, the lack of sufficient cooling when caravan towing suggests an underlying issue apart from the lo/hi speed fan behaviour. Radiator, water pump, thermostat, there's not much else involved.

TC

[andrewinpopayan]

Change the 0.47 ohm resistor for a 0.22 ohm resistor, fan will spin faster on low speed?

[FrenchMike]

Change the 0.47 ohm resistor for a 0.22 ohm resistor, fan will spin faster on low speed?

Faster,sir ..:}

[rovertone]

Having tested that the coolant temperature triggered the fan ok on 1st speed my objective with the dyno run was to test the fan at the higher coolant temperature, objective achieved because i got the answer.

But also the key factor on the dyno was that with the auxillary high velocity fan blowing it didn't overheat, it got to 105deg which I wouldn't consider overheating given the engine load. I am not sure whether the temp would have risen any higher if we had sustained the loading but given that compared to the previous runs without the fan, it remained static we curtailed the run. To me this gave me confidence that the cooling system was working.

Having done that, for me, the first priority is to fix the fan, a 'belt & braces' addition would be then to fit a new pump & stat.

If I achieve that I won't know whether problem is fixed till faced again with another spanish climb 'cos I am not fancying paying out for another dyno session.
If I do that and still have a problem then for me I'll have to stick to UK touring or get a 4x4 tug!

Tony

[HenryD]

I had a similar issue to this with a Vauxhall Omega,solo it could be driven as fast and hard as you like and temp wouldn't move,hitch a caravan too it and it would heat up on long hills,thats with twin electric fans and an engine driven jobbie too.
Changed the Rad eventually and it solved the problem completely even though I could find nowt wrong with the old one

[spyder]

Just been towing my 1400 odd kg van following cars doing 40 up some steep hills. Temperatures were around 86-93 and once saw 102. It came down very quickly. I switched the air con on a few times and the temperature fell accordingly. I found that sport mode kept the temperatures lower at all times.

Craig

[SD1too]

Just been towing my 1400 odd kg van following cars doing 40 up some steep hills. Temperatures were around 86-93 and once saw 102. It came down very quickly. I switched the air con on a few times and the temperature fell accordingly.
Thank you for that relevant evidence Craig. It is exactly how I would expect a functional cooling system to behave. This is why Tony's sustained temperature of 105° with plenty of air flow through the radiator indicates to me that his problem isn't with the electric fan.

Simon

[rovertone]

Thanks Craig, it has been suggested to me that sport mode works well towing, I will be trying that next time i am out.

My problem is only on the severest of hills, on lesser ones I have had similar experience to yourself re temps and on occasions slightly hotter. I found on my return that the aircon was overheating so a hot condenser would not have been helping.

[rovertone]

I have now got the front off and hopefully I will have attached pics of the fan control box.
It is a Siemens marked V23143-A1-X13 PWM2

I have no history of whether it is the original or whether it was fitted when the fan was changed to 2 speed (I am told that being an 03 reg it would have definately started life as 3 speed)

Does this look ok?

Thanks
Tony

[FrenchMike]

Hi,

It's effectively a two speed config .

You can test the PCB simply :

1 remove the big 80 Amp fuse to prevent any danger .(no power to motor)


2 (ignition ON) via a small wire touch the grey/blue red (your second pict) to earth.

You must hear in silent environment the two relays clicking in turn.

Then remove to reverse.

Mike

[RayH]

I have now got the front off and hopefully I will have attached pics of the fan control box.
It is a Siemens marked V23143-A1-X13 PWM2

I have no history of whether it is the original or whether it was fitted when the fan was changed to 2 speed (I am told that being an 03 reg it would have definately started life as 3 speed)

Does this look ok?

Thanks
Tony

Yes, it does look OK. So the mystery remains :duh:

While it is out it may be worth checking the resistance of the red/blue wire back to the ECU assuming you have a meter.
I'd disconnect the plug from the ECU before metering the lead.

[FrenchMike]

While it is out it may be worth checking the resistance of the red/blue wire back to the ECU assuming you have a meter.
I'd disconnect the plug from the ECU before metering the lead.

Hi Ray ,no need ,the trinary switch normally put this input to earth .
so no risk..:shrug:
And with what i now know ,both relays sequentially are activated ..
To check the PWM signal from the ECU,it's another story ...without a scope .

Mike

[SD1too]

Yes, it does look OK. So the mystery remains :duh:

No mystery Ray! :D As I ventured a few pages ago, the fan isn't the problem. ;)

But whilst it is dismantled, Tony should earth the blue/red & grey PCB connection as French Mike suggests to test the PCB. They do sometimes malfunction.

Simon

[rovertone]

Hi,

It's effectively a two speed config .

You can test the PCB simply :

1 remove the big 80 Amp fuse to prevent any danger .(no power to motor)


2 (ignition ON) via a small wire touch the grey/blue red (your second pict) to earth.

You must hear in silent environment the two relays clicking in turn.

Then remove to reverse.



Mike
Done that just on the one tab with the grey/blue red and relay clicks both when contact is made and then when released so guess that's all ok. I think it will have to be a 'botch' and put a discreet switch into the trinary switch wires to switch on 2nd speed manually on the very rare occasions I will need it.

One final thought is it feasible that the coolant sender signal strength is strong enough to work the OBD digital readout but not enough to trigger the fan relay?

Thanks for your help I think i'll start putting it back together!

Tony

[rovertone]

No mystery Ray! :D As I ventured a few pages ago, the fan isn't the problem. ;)

But whilst it is dismantled, Tony should earth the blue/red & grey PCB connection as French Mike suggests to test the PCB. They do sometimes malfunction.

Simon

Simon,
I am hearing what you say re cooling system efficiency but if I have proven the fan is not working correctly so I must also try and sort that. Freeing up any malfunction in the coolant flow will not fix it, as i have said previously the staged fan operation is surely part and parcel of the system.

Connection tested ok.

Tony

[RayH]

Hi Ray ,no need ,the trinary switch normally put this input to earth .
so no risk..:shrug:
And with what i now know ,both relays sequentially are activated ..
To check the PWM signal from the ECU,it's another story ...without a scope .

Mike

Hi Mike, just trying to establish why the trinary switch will activate high speed but not the temperature rise :shrug:

No mystery Ray! :D As I ventured a few pages ago, the fan isn't the problem. ;)

But whilst it is dismantled, Tony should earth the blue/red & grey PCB connection as French Mike suggests to test the PCB. They do sometimes malfunction.

Simon

You may well be right in that it isn't the only problem, but from the temperature ranges you gave earlier there clearly is a problem if the high speed didn't kick in before 115.

Oh! And removing the plug from the sensor only gives low speed.

[SD1too]

Done that just on the one tab with the grey/blue red and relay clicks both when contact is made and then when released so guess that's all ok.
Errr ... maybe not Tony. Mike quite correctly said that you need to determine that both relays operate. You haven't said that. Please make sure that you do that before reassembling. Placing a finger on the relay casing sometimes helps.
I think it will have to be a 'botch' and put a discreet switch into the trinary switch wires to switch on 2nd speed manually on the very rare occasions I will need it.
:devil: No "botches" allowed here Tony! ;)
You're determined to discount a thermostat problem or your radiator flow impeded by that awful sealant stuff you put in, aren't you?
In an earlier post I asked you to grasp the bottom radiator hose to test its temperature. This will tell you whether the thermostat is opening fully. I didn't get a reply. :o Will you do that please?
... is it feasible that the coolant sender signal strength is strong enough to work the OBD digital readout but not enough to trigger the fan relay?
Now you're clutching at straws Tony! You won't be the first though. It's funny how some are convinced that they have an incredibly rare and complicated fault to the exclusion of the simple things staring them in the face!

This is a fascinating case though. Please keep up the posts. I can't wait to find out what it really is. :}

Simon

[FrenchMike]

One final thought is it feasible that the coolant sender signal strength is strong enough to work the OBD digital readout but not enough to trigger the fan relay?

Thanks for your help I think i'll start putting it back together!

Tony

Hi Tony,
Unfortunatey it's more complicated .all is ECU controlled !

Coolant sender->ECU->digital conversion->display->PWM signal to Fan PCB.

As follow: (post#57)
http://www.the75andztclub.co.uk/forum/showthread.php?t=222452&page=6

Ideally,for overall tests ,the little PWM generator discribed on post #1
could be useful :}

Mike

[rovertone]

Sorry Simon have I missed something, I earthed out the middle tab with the two wires grey/blue red. Now is it grey or pale blue. Should I have done the same with the single dk grey?

I did carry out all the things you suggested including grasping the hoses see post 19

Tony

[rovertone]

Got it!

2 clicks on, 2 clicks off. I'll start putting it back now (between thunderstorms!)

[Union Wheels]

Hi rovertone,

just to recap. the position :-

Slow speed ok with screen demist on

Fast speed ok with trinary test

Fast speed ok with T4 test.

No fast speed when engine temperature sensor disconnected (only slow speed)

Logically therefore the pulse width modulator signal to trigger high speed is not working, missing or low in amplitude.

I would suspect the printed circuit board in the fan control box is faulty and would be easy to substitute to prove it one way or the other.

My other suggestion would be an intermittent high speed relay (burnt contacts) which you could also replace easily.

When you get the fast speed working, do not rule out the possibility of the radweld additive having an adverse effect on the cooling system, as the heater matrix on a diesel is normally enough to cool the engine without the radiators help.

Cheers, Pete.

[rovertone]

Hi Pete,
Your recap is spot on.

Can you advise me where I could source the correct PCB and relays, electronics is not my forte

Maybe a complete new fan and control box from Jules would be a solution, albeit more costly.

I will be flushing the system again, and because of the solo cool running, replacing the stat and may as well replace the pump for good measure (108k on clock) given I hope to be towing back and forth to Portugal twice a year.
I have had the heater matrix out and flushed it through with boiling water a few times, the heater does work ok. My concern is not being able to get a good flush with the thermostat in and/or whether I clear everything out of the engine. The radweld product was only in for a very short time (1 mile) before the system was drained to fit the new rad so hoping it didn't get too much chance to gunge up.

Thanks for your input
Tony

[SD1too]

No fast speed when engine temperature sensor disconnected (only slow speed) ... Logically therefore the pulse width modulator signal to trigger high speed is not working, missing or low in amplitude.
The trouble is Pete, Tony has posted this:
On my way home on occasions I heard the high speed fan come on ...
:shrug:
I would suspect the printed circuit board in the fan control box is faulty ...
Tony has just earthed the PCB input and heard both relays operate, so the electronics works in those circumstances. If you're suggesting that the PCB isn't recognising the high speed PWM command, then how does it work properly under test with T4?
Sorry, it's unsafe to conclude that the PCB is faulty.
My other suggestion would be an intermittent high speed relay (burnt contacts) ...
The relay has just been proven.

Can you advise me where I could source the correct PCB and relays ..
You have got the correct PCB and relays. I can see that from your photos and your test.
Maybe a complete new fan and control box from Jules would be a solution, albeit more costly.
Your problem is not the fan!

... because of the solo cool running ...
What does "solo cool running" mean please Tony? :shrug: :confused:

Simon

[Union Wheels]

Hi SD1too,

I think you are assuming that a T4 test for high speed fan adjusts the duty cycle of the pulse width modulator. This may be the case, but it could also use another path to check the fan runs at high speed.

An intermittent relay is just that, it may not work all the time, and the fact that you can hear it click does not mean it will pass current.

You must also consider the fact that high speed is not achieved when the engine temperature sensor is unplugged, and replacing the P.C. board would rule out the possibility of a faulty board.

Pete.

[Dragrad]

Threads merged at the request of the OP.;)

[Union Wheels]

Hi rovertone,

your best chance of obtaining a printed circuit control panel is to contact "Arctic" on this forum he is the man who has done a lot of work on fans and seems to have many spares.

Pete.

[rovertone]

Solo driving without the caravan its 79/81, peaking at 84/85. In Portugal with temps in the 30's it wasn't much different.

To clarify my comment re hearing the 2nd speed fan, that wasn't in relation to any high coolant temperature, on one occasion it was when we were without the caravan, given my subsequent findings this was likely due to aircon overheat thus triggered by trinary switch.

We have to put this problem in context, I travelled c 3600 miles towing and had I been using only the temp gauge I would have only seen it move above normal about 6 times, 4 of those where I was in an overheat situation that cut engine to 'safe mode'.
With the benefit of greater knowledge, on the return journey I travelled with the OBD display and although I only had 'safe mode' on one climb I noted that the temp gauge did run into the 100's but given it didn't exceed 115C the gauge would have stayed 'normal'. Each time when the engine load eased the temp dropped back (high 80's/90's). Ambient temp was mostly high 20's/30's and I likely had a hot condenser.
To me this suggests that the running temps given the load are there or thereabouts and the cooling system must be working reasonably well but lacks that extra boost of air at extremes when road speed is lower.
I still maintain engine temps would be expected to reach such levels under certain circumstances otherwise why would Rover have put a progressive fan system in place.

If my view is wrong what engine temperatures should I be seeing in such a scenario? If all else fails I will have to put in a 'botch' switch and see what happens next trip. That's if Mrs Rovertone will chance it again, she's been looking at V70's!

[SD1too]

I think you are assuming that a T4 test for high speed fan adjusts the duty cycle of the pulse width modulator. This may be the case, but it could also use another path to check the fan runs at high speed.
Pete; if you look at French Mike's drawing of the PCB circuit, there is no other way (other than creating its own PWM signal) that T4 could trigger the relays. If you can think of another path, please let us know! :}
An intermittent relay is just that, it may not work all the time, and the fact that you can hear it click does not mean it will pass current.
In theory I agree, but in practice automotive relays are extremely reliable.
You must also consider the fact that high speed is not achieved when the engine temperature sensor is unplugged ...
Actually this is an assumption. I quote from RAVE on the diesel's engine management system:
"In the event of ECT failure, the ECM ... will also run the cooling fan when the ignition is switched on to protect the engine from overheating."
Note that it does not specify high speed.

So the evidence does not prove that there is a fan fault.

Tony; having said that you heard the high speed fan operating, you're now speculating that this was "likely due to aircon overheat". I'm afraid that guesses like this are useless when it comes to reliable fault diagnosis.

Similarly you say that you "likely had a hot condenser". Speculation again with no facts to back it up.

I say again, it seems to me that you have an inefficient cooling system. I am satisfied that your fan is working on both speeds, but it's most likely that the additives put into the cooling system are causing irregular overheating effects which are virtually impossible to predict reliably. Indulging in bodgery by installing switches to activate faster fan speeds is not the answer.

Your thread is, I'm sorry to say, beginning to read like a "wind up".

Simon

[rovertone]

Simon
My view on the aircon overheating was based on the fact that when I returned home I discovered that at idle the fan was cycling between 1st and 2nd speed with the aircon switched on. The HP pipe within 10 secs of switching on the aircon was too hot to touch, hence i replaced the condenser, problem now solved. This failure must have built up over a period of time so I think my assumption on why I heard the fan was sound.

I am sorry you think this is a wind up, I can assure you it is not and I resent that remark. I don't go spending the thick end of £100 on a rolling road on a whim chasing a figment of my imagination.

I have worked around cars long enough to know my way round and have solved many problems.
I have found it frustrating that you keep telling me that the problem is with my cooling system and seem to want to disregard the fact that my fan has no bearing on temperature. At high temperatures 2ND SPEED IS NOT WORKING!

Thanks for you input and advice I'll progress as I see fit till I eventually solve the problem.

[RayH]

Actually this is an assumption. I quote from RAVE on the diesel's engine management system:
"In the event of ECT failure, the ECM ... will also run the cooling fan when the ignition is switched on to protect the engine from overheating."
Note that it does not specify high speed.

We do know this from my car though.
With the sensor disconnected the fan runs at high speed :shrug:


So the evidence does not prove that there is a fan fault.

115 on the dyno and no high speed?

What other evidence is needed Simon?

I did refer to these points in this (http://www.the75andztclub.co.uk/forum/showpost.php?p=2078308&postcount=125)post but it seems to have been overlooked.

[SD1too]

We do know this from my car though.
With the sensor disconnected the fan runs at high speed
Morning Ray, and thank you for this. I take it then that you've satisfied yourself that you're not hearing the low speed which can sound so noisy on a 2 speed system that it's easily mistaken for the high speed? This has happened, more than once, and I've heard 'resistor' slow speed fans running on the KV6 and I would have guessed that I was hearing fast speed.

But there's another point to consider. What is being suggested is that the ECM is providing a PWM signal limited to low fan speed operation, irrespective of the input from the coolant thermistor. If true, that would be a unique fault condition, and would need to be proven using an oscilloscope.
115 on the dyno and no high speed?
What other evidence is needed Simon?
The problem I am having Ray is that we've now reached 139 posts :eek: and Tony has provided an awful lot of evidence, scattered hither and thither, making it difficult (for me, at least) to get a clear picture. However, I have trawled through the thread again and found this in response to your question: "115 on the dyno and no high speed?"
... the key factor on the dyno was that with the auxillary high velocity fan blowing it didn't overheat, it got to 105deg ...
So, as I understand it, the dyno operator had a high power fan directed at the radiator to provide cooling. With this, Tony says that the temperature reached 105° not 115°. Now, I may have missed another post which supports your point, so if you can find one please quote it! :D

My second point is that, if Tony's cooling system was working properly, his slow speed fan should keep the temperature below 100°, and it does:
Under no load conditions I have proved that at 97deg the 1st speed pulls temp down immediately.
Tony also says
The engine runs too cool solo (79/81)
By "solo" Tony has explained that he means 'not towing his caravan'. Now, that's more like the temperature we would expect from a diesel isn't it?

So, Tony's temperature varies widely from the cool running we would expect to sustained 105° even with forced fan assistance. I should have noticed this trend before, so thanks Ray for persisting with questioning me, but this indicates that Tony's cooling system isn't pressurising. This can result from worn expansion tank cap sealing rings or a loose hose connection or maybe a leaky bleed screw. The cause won't be quick or easy to find, and for goodness sake don't put sealing products into the coolant :o, but this is where I believe Tony's efforts should be concentrated.

If you're still unconvinced, consider spyder's account of the same conditions that Tony experienced:
Just been towing my 1400 odd kg van following cars doing 40 up some steep hills. Temperatures were around 86-93 and once saw 102. It came down very quickly.
Note that the temperature "came down very quickly" at 102°. That's slow fan speed territory, not high. Tony's slow speed fan isn't bringing down the temperature from 105°. It isn't even reducing with the dyno's high velocity fan, which is probably far superior to the car's own high speed fan. Doesn't that show that fan assistance is not the problem Ray?

Regards,

Simon

[RayH]

Morning Ray, and thank you for this. I take it then that you've satisfied yourself that you're not hearing the low speed which can sound so noisy on a 2 speed system that it's easily mistaken for the high speed?

Absolutely Simon, the fan was on the floor at the time following the replacement of my own fan control. As posted at that time I observed, as well as heard, the fan running at high and low speeds in response to:
Demist - low
Trimsary - high
Disconnected sensor - high
Original post here (http://www.the75andztclub.co.uk/forum/showpost.php?p=2052952&postcount=55)


But there's another point to consider. What is being suggested is that the ECM is providing a PWM signal limited to low fan speed operation, irrespective of the input from the coolant thermistor. If true, that would be a unique fault condition, and would need to be proven using an oscilloscope.

I don't know if it is "irrespective" of the input from the thermistor but possibly due to a high resistance connection somewhere, or even a component out of spec, the high speed is not being activated at the correct temperature.
Do we know how the T4 initiates high speed, does it choose a temperature a few degrees above the normal cut-in or does it simply say "this will do it" and simulate 140 degrees?
Am I wrong in thinking that the T4 test is simply to check that the fan will operate at 2 (or 3) speeds rather than operating within the specified temperature ranges?


The problem I am having Ray is that we've now reached 139 posts :eek: and Tony has provided an awful lot of evidence, scattered hither and thither, making it difficult (for me, at least) to get a clear picture.


You must remember Simon that not everyone has a mind that operates in a methodical way such as yours. I have this problem with my wife :D
Often further details are recalled at a later date and you re-assess what you thought happened earlier. :shrug:

It has been a long and interesting (frustrating even) thread certainly but I'm not sure that suggesting Tony is winding us up will actually resolve it :eek:


However, I have trawled through the thread again and found this in response to your question: "115 on the dyno and no high speed?"

So, as I understand it, the dyno operator had a high power fan directed at the radiator to provide cooling. With this, Tony says that the temperature reached 105° not 115°. Now, I may have missed another post which supports your point, so if you can find one please quote it! :D

"I had a session today and I got the proof! At 115deg with temp gauge moving off 'normal' the fan was on 1st speed only. This was done several times without any auxillary test bed fan. " from this (http://www.the75andztclub.co.uk/forum/showpost.php?p=2075788&postcount=79)post ;)

My second point is that, if Tony's cooling system was working properly, his slow speed fan should keep the temperature below 100°, and it does:

Tony also says

By "solo" Tony has explained that he means 'not towing his caravan'. Now, that's more like the temperature we would expect from a diesel isn't it?


That as may be, but you can't discount the existence of a fault simply because you believe a different fault exists :shrug:
I have clearly stated previously that there may be a circulation problem but nonetheless there is also a fan problem. It would be wise to resolve both.

So, Tony's temperature varies widely from the cool running we would expect to sustained 105° even with forced fan assistance. I should have noticed this trend before, so thanks Ray for persisting with questioning me,

I do my best ;)

but this indicates that Tony's cooling system isn't pressurising. This can result from worn expansion tank cap sealing rings or a loose hose connection or maybe a leaky bleed screw. The cause won't be quick or easy to find, and for goodness sake don't put sealing products into the coolant :o, but this is where I believe Tony's efforts should be concentrated.

As above, if he has two faults then they both need to be resolved.

If you're still unconvinced, consider spyder's account of the same conditions that Tony experienced:

He was also in Portugal with ambient temperatures in the 30s was he?

Note that the temperature "came down very quickly" at 102°. That's slow fan speed territory, not high. Tony's slow speed fan isn't bringing down the temperature from 105°. It isn't even reducing with the dyno's high velocity fan, which is probably far superior to the car's own high speed fan. Doesn't that show that fan assistance is not the problem Ray?

I refer the Honourable Gentleman to my earlier answer :D

Kind regards (sincerely meant)
Ray

[T-Cut]

Tony's temperature varies widely from the cool running we would expect to sustained 105° even with forced fan assistance. - - - - - this indicates that Tony's cooling system isn't pressurising.

Loath though I am to open a third chapter in this saga, I have to ask what the logic is behind this assertion?

TC

[SD1too]

Absolutely Simon ... I observed, as well as heard, the fan running at high and low speeds in response to: ... Disconnected sensor - high
OK, many thanks for that clear confirmation.
Do we know how the T4 initiates high speed ..
I don't, but I cannot speak for anyone else. ;)
Am I wrong in thinking that the T4 test is simply to check that the fan will operate at 2 (or 3) speeds ...
No, you're not wrong Ray. T4 simply triggers the relays in turn. Now, on the diesel this must mean that the PWM input to the PCB is used because there is no other way of doing it! Tony is telling us that T4 successfully operates both his speeds. That evidence suggests that the PCB and relays are working, doesn't it? Tony further tested the relays by manually earthing the trinary input and again they worked. Yet he believes that the high speed is not working in response to the PWM signal from his car's ECM.

The coolant temperature sender is connected only to the ECM, so the ECM also supplies data to the instrument pack to feed the gauge and the digital diagnostic display. These appear to be showing high coolant temperatures satisfactorily, so wouldn't that rule out a defective temperature sender?

So I am being asked to accept that there is an internal fault with the ECM which has never been reported before, not even by people whose ECMs have suffered immersion in plenum chamber rainwater!

"I had a session today and I got the proof! At 115deg with temp gauge moving off 'normal' the fan was on 1st speed only. This was done several times without any auxillary test bed fan. " from this (http://www.the75andztclub.co.uk/forum/showpost.php?p=2075788&postcount=79)post ;)
Thanks for finding that Ray. I know from experience that when sitting in the car with the engine running above idle, I could not be certain whether my 3 speed fan was running or not. There's just too much ambient noise. With a 2 speed resistor system, the difference between low and high speeds is much less, making it even more difficult to detect the change, but obviously Tony's hearing is much sharper than mine.
He was also in Portugal with ambient temperatures in the 30s was he?
He doesn't say. Was the ambient temperature in the thirties at the dyno session do you think? ;)
But in any case, as you know, heat exchange should still take place in those conditions otherwise all the HGVs in Italy and Spain would be boiling over all the time!

And even with powerful fan assistance on the dyno, Tony's temperature was no lower than 105. That's very hot for a diesel, suggesting a cooling system fault other than the fan.

If someone can get a 'scope on the blue/red PWM wire I would be very interested in the result, but I don't think that's on the cards.

Simon

[FrenchMike]

Hi Simon, if the resistor divider R6,R8 is out of range ,(threshold too high).

The high speed could never activate ! though the earthing test is correct ...

remember in that case a positive ramp is generated on C9 (0 to V batt)
Without the action of the PWM signal


Mike

[SD1too]

... I have to ask what the logic is behind this assertion?
Just personal experience TC. My SD1 once developed very high temperatures (100° - 110°) but not consistently so. Thermostat and fan assistance were OK. It took a long time to find the cause. A brazed joint had failed on the metal expansion tank which I deduced would stop the cooling system pressurising. Once this was fixed, the temperatures dropped.

I can't fully explain it, but you probably can. ;)

Hi Simon, if the resistor divider R6,R8 is out of range ,(threshold too high). The high speed could never activate
If that was the case, how would T4 manage to activate high speed do you think? Thanks for joining-in Mike! :}

Simon

[FrenchMike]

If that was the case, how would T4 manage to activate high speed do you think? Thanks for joining-in Mike! :}

Simon

Of course but apparently nobody knows how is made the T4 test ?

Imagine,it's an earthing of the PWM output ? :shrug:

[SD1too]

Imagine,it's an earthing of the PWM output ? :shrug:
It cannot be that Mike. T4 can trigger low and high fan speeds as the user chooses (and medium too on 3 speed systems).

Any other ideas? :shrug:

Simon :}

[RayH]

That evidence suggests that the PCB and relays are working, doesn't it? Tony further tested the relays by manually earthing the trinary input and again they worked. Yet he believes that the high speed is not working in response to the PWM signal from his car's ECM.

The coolant temperature sender is connected only to the ECM, so the ECM also supplies data to the instrument pack to feed the gauge and the digital diagnostic display. These appear to be showing high coolant temperatures satisfactorily, so wouldn't that rule out a defective temperature sender?

So I am being asked to accept that there is an internal fault with the ECM which has never been reported before, not even by people whose ECMs have suffered immersion in plenum chamber rainwater!

I think we agree on the first two paragraphs.
As far as the third paragraph goes, why not?
Some component(s) in the ECM receives the output from the sensor and reacts accordingly. Is is beyond the realms of possibility that these could be out of tolerance and therefore not produce the correct signals at the correct temperatures?

In relation to the flooded plenum ECMs, as we know this invariably affects the fuel pump supply and the vehicle fails to start.
Under such conditions overheating is not a problem :shrug:

The fact that it has not previously been reported has no bearing on the current situation. There could be any number of cars with the same potential fault that do not tow, or do not have another coolant problem that necessitates the extra cooling ;)


Thanks for finding that Ray. I know from experience that when sitting in the car with the engine running above idle, I could not be certain whether my 3 speed fan was running or not. There's just too much ambient noise. With a 2 speed resistor system, the difference between low and high speeds is much less, making it even more difficult to detect the change, but obviously Tony's hearing is much sharper than mine.

That does surprise me as the high speed fan on both of mine have been clearly audible at rest and low road speeds. I know this from a previous resistor failure with the high speed fan cutting in and out.


He doesn't say. Was the ambient temperature in the thirties at the dyno session do you think? ;)

Indeed he doesn't, so why would you assume that the conditions were the same?
I doubt the ambient was as high on the dyno session, but as pointed out previously, meither do we know what load it was put under.

But in any case, as you know, heat exchange should still take place in those conditions otherwise all the HGVs in Italy and Spain would be boiling over all the time!

Only when their fans fail too :getmecoat:

And even with powerful fan assistance on the dyno, Tony's temperature was no lower than 105. That's very hot for a diesel, suggesting a cooling system fault other than the fan.

If someone can get a 'scope on the blue/red PWM wire I would be very interested in the result, but I don't think that's on the cards.

Simon

Again we don't know how much load it was under.
So while it is hot for a diesel under normal load in the UK such temperatures must have been envisaged at design or we wouldn't be looking at two speed fans on the diesel. :shrug:

No, unless Tony plans buying a scope or visiting French Mike then probably not.

[T-Cut]

I can't fully explain it, but you probably can. ;)


Yes probably.
I was simply wondering why there's been no mention of coolant/pressure venting even though the system was running at 115C at one point. With a pressure cap in good order, this temperature won't vent the valve.

TC

[RayH]

Hi Simon, if the resistor divider R6,R8 is out of range ,(threshold too high).

The high speed could never activate ! though the earthing test is correct ...

remember in that case a positive ramp is generated on C9 (0 to V batt)
Without the action of the PWM signal


Mike

What if the fault was at the ECM though Mike?
Is it feasible that the ECM is supplying an out of spec signal to the fan control?

Not far enough out to fail completely but enough to raise the cut in temperature by say 5 or 10 degrees?

[Phil-T4]

FYI - The T4 instructs the ecu to turn the fans on, so if they work when forced then the PWM signal is correct, the circuit board and relays are ok and the fan motor works.

[SD1too]

FYI - The T4 instructs the ecu to turn the fans on ...
On the diesel Phil, can the T4 be instructed to turn on the slow speed fan only?

Simon

[Phil-T4]

When you force the outputs the first option is the low speed fan setting, then you move onto the medium and eventually the high as the PWM voltage is ramped up by the ecu.

[SD1too]

When you force the outputs ... the PWM voltage is ramped up by the ecu.
So the T4 instructs the car's ECM to produce its normal PWM waveform? The T4 doesn't provide its own PWM to trigger the control box circuit? Have I got that right?

Simon

[Phil-T4]

So the T4 instructs the car's ECM to produce its normal PWM waveform?

Yes, that is correct..

[SD1too]

Thank you very much for your help Phil. :bowdown:

Ray; I think we've taken an important step forwards. What Phil has told us appears to rule out your suggested ECM fault.

Simon

[FrenchMike]

Hi Phil,

I guess , the ECU ignores if it's a 3 or 2 speed ?

About PWM ratio ,Rave says :

low 13%
Med 44%
High 85%

Is it exact ?

Mike

[Union Wheels]

Hi all followers of this thread,

today I disconnected the coolant temperature sensor to check what happens to the radiator fan.

Upon unplugging the connector nothing happened.

Turn on the ignition switch and the fan ran at high speed.

Turn off the ignition switch and the fan continued to run at high speed until battery was disconnected.

This backs up what "RayH" says, and if this does not happen in "rovertones" case, he has a fault in his high speed switching which needs repairing.

You will note that I asked near the beginning of this thread if a radiator sealant had been used, and I said then that this would very likely cause problems.

I still think that the printed circuit board in the fan control box is faulty or out of spec, and if it were mine I would substitute or repair same.

Cheers, Pete.

[Phil-T4]

I believe it does Mike, regards of what fan is fitted the test procedure always has the 3 speeds and the 2 speed fan ZCS code is only for the KV6's.

I couldn't tell you of the values are exact or not but even with component drift they should always be around those figures.

[Union Wheels]

Hi rovertone,
you said in one of your previous posts that you would have difficulty in replicating the test on the rolling road and did not fancy paying the "thick end of £100" for another session.

I was thinking that if you obtained another coolant temperature sensor from a breaker, you could connect this outside the engine and play a hair drier on it, watching the obd temperature and see if and when the fan triggered.

Just a thought, Pete.

[RayH]

Thank you very much for your help Phil. :bowdown:

Ray; I think we've taken an important step forwards. What Phil has told us appears to rule out your suggested ECM fault.

Simon

I'm not sure that we have :shrug:
As I was asking earlier, and Phil hasn't confirmed either way (Phil I appreciate this is something that you wouldn't necessarily know as in normal use it wouldn't be relevant) does the T4 simulate the cut-in temperatures or simply exceed them by a number of degrees.

For example you quoted
Low 100°
Medium 106°
High 112°

T4 may simulate
105, 110 and 120
In which case the results would still be positive and allow for Tony's observations.

Hi rovertone,
you said in one of your previous posts that you would have difficulty in replicating the test on the rolling road and did not fancy paying the "thick end of £100" for another session.

I was thinking that if you obtained another coolant temperature sensor from a breaker, you could connect this outside the engine and play a hair drier on it, watching the obd temperature and see if and when the fan triggered.

Just a thought, Pete.

I wish I'd thought of that :bowdown:

[FrenchMike]

Hi rovertone,
you said in one of your previous posts that you would have difficulty in replicating the test on the rolling road and did not fancy paying the "thick end of £100" for another session.

I was thinking that if you obtained another coolant temperature sensor from a breaker, you could connect this outside the engine and play a hair drier on it, watching the obd temperature and see if and when the fan triggered.

Just a thought, Pete.

Alright,it's the best overall test ...

[T-Cut]

Today I disconnected the coolant temperature sensor to check what happens to the radiator fan.
Upon unplugging the connector nothing happened.
Turn on the ignition switch and the fan ran at high speed.
Turn off the ignition switch and the fan continued to run at high speed until battery was disconnected.

On the last step here, did you leave it long enough before disconnecting the battery? I'm interested because RAVE doesn't indicate a heat soak cooling period for the diesel. The 'unknown' temperature condition invoked by sensor disconnection is (I suspect) analogus to a heat soak event. In this condition, the V6 and the 1.8 will each run for several minutes (up to ten minutes and five minutes respectively) before the fan stops. It would be logical for the diesel to behave similarly, rather than flattening the battery - though I don't think that is likely.

TC

[Union Wheels]

Hi T-cut,

I tried to reconnect the plug and sensor with the fan running, it is quite an awkward connection to make and the high speed fan in my ear was not helping. In the end I disconnected the battery.
The fan ran for 3-4 minutes before I ditched the battery so not conclusive

Pete.

[RayH]

Hi T-cut,

I tried to reconnect the plug and sensor with the fan running, it is quite an awkward connection to make and the high speed fan in my ear was not helping. In the end I disconnected the battery.
The fan ran for 3-4 minutes before ditched the battery so not conclusive

Pete.

I did manage to reconnect mine and unsurprisingly the fan stopped within seconds.

[Phil-T4]

I'm not sure that we have :shrug:
As I was asking earlier, and Phil hasn't confirmed either way (Phil I appreciate this is something that you wouldn't necessarily know as in normal use it wouldn't be relevant) does the T4 simulate the cut-in temperatures or simply exceed them by a number of degrees.



The T4 doesn't simulate anything it instructs the ECU to operate the PWM output, this is handled internally in the ECU's firmware.

[RayH]

The T4 doesn't simulate anything it instructs the ECU to operate the PWM output, this is handled internally in the ECU's firmware.

Perhaps my use of the word simulate is misleading.

In this context I would say the T4 is simulating a temperature rise, because it obviously isn't a rise in temperature that is turning the fan on.

It is making the ECU think that some condition has been met.

[Phil-T4]

NO, its not simulating a temperature rise or anything like that, it simply tells the ECU to output a PWM signal to the fan control box, it works like this.....

T4 to ECU - switch low fan on ecu - outputs low pwm signal
T4 to ECU - switch medium fan on ecu - outputs middle PWM signal
T4 to ECU - Switch high fan on ecu - outputs high PWM signal
T4 to ECU - Switch fan off ecu - outputs no pwm signal

[RayH]

NO, its not simulating a temperature rise or anything like that, it simply tells the ECU to output a PWM signal to the fan control box, it works like this.....

T4 to ECU - switch low fan on ecu - outputs low pwm signal
T4 to ECU - switch medium fan on ecu - outputs middle PWM signal
T4 to ECU - Switch high fan on ecu - outputs high PWM signal
T4 to ECU - Switch fan off ecu - outputs no pwm signal

So in that case it is possible for the T4 to be switching the fan on correctly but for the high speed not be be switched on by a temperature rise at the sensor.

[T-Cut]

The fan ran for 3-4 minutes before ditched the battery so not conclusive.

I did manage to reconnect mine and unsurprisingly the fan stopped within seconds.

It would certainly add some new knowledge if the sensor disconnected state could be allowed to run it's course. The data for the diesel in this condition isn't recorded as far as I knowl, so clearly valuable info. It would be illogical for the system to run the fan until the battery goes flat. Imagine a real situation where the sensor connector comes off or the signal is lost for whatever reason.

Anyone willing to run the test?

TC

[RayH]

It would certainly add some new knowledge if the sensor disconnected state could be allowed to run it's course. The data for the diesel in this condition isn't recorded as far as I knowl, so clearly valuable info. It would be illogical for the system to run the fan until the battery goes flat. Imagine a real situation where the sensor connector comes off or the signal is lost for whatever reason.

Anyone willing to run the test?

TC

Yes, if it ever stops raining here :D
Like you I would imagine that it will shut down of its own accord.
I may have dreamt it but I thought that I'd read somewhere it did :shrug:

[rovertone]

Hi rovertone,
you said in one of your previous posts that you would have difficulty in replicating the test on the rolling road and did not fancy paying the "thick end of £100" for another session.

I was thinking that if you obtained another coolant temperature sensor from a breaker, you could connect this outside the engine and play a hair drier on it, watching the obd temperature and see if and when the fan triggered.

Just a thought, Pete.

What a good idea! I have a guy very close who specialises in Rover spares, I went to see him yesterday to see if he had a complete fan & control box off a Mk2, he had but sold it last week! I go see him again in the morning I'll be surprised if he hasn't got a sender.

I am not sure how to input all the 'quotes' so please excuse the methodology of responses to questions in the last few posts.

Ref#143
1. On the dyno test I verified fan speed by listening and looking into the grille, which is what I did when I ground to a halt on the last hill albeit because of the precarious location and traffic noise it was only a cursory check, hence the need to verify.

2. Correction: With powerful fan assistance the temp didn't rise above 105deg as opposed to no auxillary fan where temp just kept rising to 112/113 where we stopped to check and found car fan only on 1st speed. To me and technician this was proof that with additional air velocity the cooling system was holding. We didn't prolong the test to check whether sustained engine load would have eventually seen the temperature rise higher but the difference between tests was significant. It is also unknown how the velocity/volume of the auxillary fan compares to the cars own 2nd speed.

Ref#148
1. Ambient temp for dyno run was c18c
2. Dyno technician (owner) was a tower himself and was clear what I wanted to achieve. As I understood it he applied a retard torque to the rollers, I think, to stop the engine driving the car faster than an equivalent of about 60mph but apparently it is not so easy with an auto as it is a balance of throttle opening versus load to stop the box downshifting. The main focus was the OBD temp to work it hard enough to get that up to fan trigger point 112deg. (assume that this is the correct tripping point)
Ref#149
I have had no sign of pressure venting even when temp went up to 119deg, and I have had no coolant loss. Rad cap all looks good.

Revert when I have tried Pete's test.
Tony

[Phil-T4]

Yes, if it ever stops raining here :D
Like you I would imagine that it will shut down of its own accord.
I may have dreamt it but I thought that I'd read somewhere it did :shrug:

Yes it will shutdown after 10 mins.

[RayH]

Yes it will shutdown after 10 mins.

Thanks Phil, that's one less job then :D

[rovertone]

Right folks Union Wheels' test done.

Before I ran the test with the 'spare' sender unit I tested again with just the plug off as follows

Aircon: OFF
Ignition: ON
Result: FAN RAN 1st SPEED, as a 'sanity' check I shorted trinary and fan stepped up to 2nd speed.
Ignition Off: Fan continued to run and shut down after 3 minutes.

Then test with spare sender connected.
Fan 1st speed triggered at 97deg, clearly heard relay engage. Fan continued at 1st speed right up to 138deg no 2nd speed or relay heard. On cool down fan switched off at c 95/96.

So there it is! Fans OK so a control box fault?

What a brilliant brainwave of Pete's and would be quite good to use to test for sure what speed the 2nd speed kicks in when I get it working.
Anyway I have a spare sender now, my local man has practically everything except a fan or gubbins. If I'd wanted an engine I could have chosen from about 8!!

Am I getting closer?
Tony

[RayH]

Right folks Union Wheels' test done.

Before I ran the test with the 'spare' sender unit I tested again with just the plug off as follows

Aircon: OFF
Ignition: ON
Result: FAN RAN 1st SPEED, as a 'sanity' check I shorted trinary and fan stepped up to 2nd speed.
Ignition Off: Fan continued to run and shut down after 3 minutes.

Then test with spare sender connected.
Fan 1st speed triggered at 97deg, clearly heard relay engage. Fan continued at 1st speed right up to 138deg no 2nd speed or relay heard. On cool down fan switched off at c 95/96.

So there it is! Fans OK so a control box fault?

What a brilliant brainwave of Pete's and would be quite good to use to test for sure what speed the 2nd speed kicks in when I get it working.
Anyway I have a spare sender now, my local man has practically everything except a fan or gubbins. If I'd wanted an engine I could have chosen from about 8!!

Am I getting closer?
Tony

So we can safely say that you weren't mistaken with the fan speeds then.

I'm not 100% certain about the diagnosis of the fan control PCB though.

If T4 forces the ECU to output its regular signal to the fan control then this would suggest it isn't, as the T4 test caused the fan to run at high speed.

From Phil's response this would appear to be the case. I had hoped he was going to say that for high speed T4 did something else but alas not.

So while it would be an easy thing to test, by substitution, I wouldn't be holding my breath.

But, yes, you are getting closer :D and well done again Pete.

[Phil-T4]

It could be a fault in the ecu then when sampling the coolant temp.
If you want I can put another one in and run that test again.

[rovertone]

Thanks Phil, I'll send you a pm

[Jules]

Sorry been away to Edinburgh Fringe!

This fault may have speeded up with some results from a very old thread. (2009 !!)
Don't take all of it as gospel as it was early days.
If you don't have a spare temp sensor use a 220 ohm variable and simulate the coolant temps.
No need to deliberately get an engine hot !!

http://www.the75andztclub.co.uk/forum/showpost.php?p=373180&postcount=11

I've talked Tony out of buying a whole new fan and control box as it sounds like all he needs a PWM board?
I'm slowly repairing a few dead ones here.

Sometime soon I will T4 some PWM's and monitor the waveform (duty cycle) at the different cut in temps/speeds.
Phil-T4 if you get chance before me let me know ;)

(I just assumed the forced outputs test alters the duty cycle? I doubt very much if it "grounds" a signal line? )

But this whole thread might be to do with something going just out of tolerance electronically (either the ECM o/p duty cycle becomes incorrect for what the PWM is calibrated to accept or a resistor changing value on the PWM board so that duty cycle no longer gets decoded properly.

I've said several times before some PWM PCB's work correctly on one car but not on another.
It shouldn't be the case but it is !

[T-Cut]

Ignition Off: Fan continued to run and shut down after 3 minutes.

Ah, so it's 3 minutes rather than 10.
Or is the heat soak case different from a sensor disconnect as far as the ignition-off run-on's concerned?

TC

[SD1too]

Fan continued at 1st speed right up to 138deg ...
138°C? :eek:
Is that what the instrument pack diagnostic digital display of coolant temperature said?
It sounds much too high to be believable doesn't it?

Simon

[SD1too]

Or is the heat soak case different from a sensor disconnect as far as the ignition-off run-on's concerned?
They are different according to MGR for the petrol engines TC.
No maximum timing is given for an invalid reading from the sensor.
For high engine temperature when the engine is switched off, the fan runs for a maximum 10 minutes for the KV6 and 5 minutes for the 1.8. No data given for the diesel.

Simon

[rovertone]

138°C? :eek:
Is that what the instrument pack diagnostic digital display of coolant temperature said?
It sounds much too high to be believable doesn't it?

Simon

Yes it was,I expect I could have taken it to 500c if I had left the hot air gun blowing a bit longer.

You seem to be trying to caste doubt over my word Simon!

[RayH]

Yes it was,I expect I could have taken it to 500c if I had left the hot air gun blowing a bit longer.

You seem to be trying to caste doubt over my word Simon!

Hot air gun?
Ah yes, that could have taken you beyond meltdown of the sensor. :eek: :D

[T-Cut]

They are different according to MGR for the petrol engines TC.

You've missed the point. I'm referring to the time the diesel fan runs on when the sensor signal is lost and ignition is switched off. Logically it will stop a set time rather than flattening the battery. I'm suggesting that this period will be the same as the heat soak period, which for the diesel, RAVE doesn't mention.

TC

[rovertone]

Hot air gun?
Ah yes, that could have taken you beyond meltdown of the sensor. :eek: :D

My missus doesn't use a hairdrier any more but one of these fancy rolling brushes not designed for under bonnet use!
I was worried about meltdown Ray, I was on my own so couldn't watch the OBD and hold the gun at the same time.

[RayH]

My missus doesn't use a hairdrier any more but one of these fancy rolling brushes not designed for under bonnet use!
I was worried about meltdown Ray, I was on my own so couldn't watch the OBD and hold the gun at the same time.

You could have tried some heated rollers instead :D :getmecoat:

So, if you were heating up, switching off and running around to check the display that was then showing 138, it's quite likely that you exceeded that at the time you switched the air gun off?

[rovertone]

You could have tried some heated rollers instead :D :getmecoat:

So, if you were heating up, switching off and running around to check the display that was then showing 138, it's quite likely that you exceeded that at the time you switched the air gun off?

Never thought of that so yes quite likely, the sensor cooled really quickly I had to rig up a cardboard shield to limit the air off the fan. Have thought of a better idea now, just need a long cone or tube to put over sensor to keep air focussed.

[SD1too]

You seem to be trying to caste doubt over my word Simon!
Not at all Tony. You see, there isn't any mention of using a hair dryer in your earlier post so my question was based on the belief that you achieved this reading by running the engine with the sensor in place.

You've missed the point. I'm referring to the time the diesel fan runs on when the sensor signal is lost and ignition is switched off ... I'm suggesting that this period will be the same as the heat soak period, which for the diesel, RAVE doesn't mention.
Rest assured TC that I didn't miss the point. Sorry if my reply misled you into thinking otherwise. :getmecoat:

To clarify, RAVE doesn't give a figure for the "heat soak period"; in fact it doesn't mention that this feature exists at all for the diesel. On that basis I don't see the value in speculating since it can easily cloud the facts.

Simon

[T-Cut]

To clarify, RAVE doesn't give a figure for the "heat soak period"; in fact it doesn't mention that this feature exists at all for the diesel. On that basis I don't see the value in speculating since it can easily cloud the facts.

Perhaps you don't Simon, but I do. Rovertone is getting there with his issue, but peripheral questions were raised and I think they're interesting. You don't have to join in or comment if they don't interest you. A lost sensor signal while driving is well within the realm of possibility. I'd like to know what happens next. The heat soak connection may or may not exist, but any info is useful. We've had two different answers to the run-on period (three minutes and ten minutes), so what's correct? You'll not find the answer in RAVE.

TC

[RayH]

Not at all Tony. You see, there isn't any mention of using a hair dryer in your earlier post so my question was based on the belief that you achieved this reading by running the engine with the sensor in place.


There were quite a few posts referring to this Simon, prior to Tony posting his results.

On that basis I don't see the value in speculating since it can easily cloud the facts.

Simon

Right, looks like it's back to me then, a job for when the rain stops again. Unless Jules has got one indoors and wants to give it a try in an idle moment :getmecoat:

[SD1too]

There were quite a few posts referring to this Simon, prior to Tony posting his results.
Ray,

If anyone posts that they have achieved a 138° reading on a diesel, to my way of thinking it is helpful and reasonable to qualify that result with an explanation of the artificial method employed to achieve it at the time that the claim is made. For example:

"Using a hairdryer blowing on the sensor tip, I achieved a reading of 138° but the fan remained running at slow speed .."

It should not be left to the reader to trawl through the whole thread looking for references, perhaps made in general discussion, then speculating on whether those references apply to the test quoted; if indeed that is what you are suggesting in your ambigious last comment.

Simon

[rovertone]

Not at all Tony. You see, there isn't any mention of using a hair dryer in your earlier post so my question was based on the belief that you achieved this reading by running the engine with the sensor in place.


Rest assured TC that I didn't miss the point. Sorry if my reply misled you into thinking otherwise. :getmecoat:

To clarify, RAVE doesn't give a figure for the "heat soak period"; in fact it doesn't mention that this feature exists at all for the diesel. On that basis I don't see the value in speculating since it can easily cloud the facts.

Simon
Union Wheels came up with the idea and states 'hair dryer' in post 172. My post 175 opens by stating 'Union Wheels' test done. Pretty obvious therefore the methodology.

[rovertone]

You've missed the point. I'm referring to the time the diesel fan runs on when the sensor signal is lost and ignition is switched off. Logically it will stop a set time rather than flattening the battery. I'm suggesting that this period will be the same as the heat soak period, which for the diesel, RAVE doesn't mention.

TC
Quite relevant, on my test the sensor cooled very rapidly immediately the heat was taken away.

[rovertone]

I have arranged a vist to see Phil T4 tomorrow morning where he hopes to test an alternative PCB and ECU as he sees fit.
I am hoping to be to be leaving him again with grin on my face (last time it was after a 160) and then putting a thick black line undr this thread!

I will let you know the outcome.

Tony

[T-Cut]

Quite relevant, on my test the sensor cooled very rapidly immediately the heat was taken away.

Indeed. But if you'd maintained the hair dryer on the sensor and turned off the ignition, how long would the fan run on? That's the question I'm asking. Since your control system seems faulty, causing the slow speed fan to persist into the overheat range, it would be equally interesting to do the experiment.

TC

[RayH]

Ray,

If anyone posts that they have achieved a 138° reading on a diesel, to my way of thinking it is helpful and reasonable to qualify that result with an explanation of the artificial method employed to achieve it at the time that the claim is made. For example:

"Using a hairdryer blowing on the sensor tip, I achieved a reading of 138° but the fan remained running at slow speed .."

It should not be left to the reader to trawl through the whole thread looking for references, perhaps made in general discussion, then speculating on whether those references apply to the test quoted; if indeed that is what you are suggesting in your ambigious last comment.

Simon

You are quite right Simon, my comment was ambiguous. I had mistakenly assumed that you were following the thread, and therefore would not have to "trawl through" as you so aptly put.
I will indeed bear this in mind.

[RayH]

I have arranged a vist to see Phil T4 tomorrow morning where he hopes to test an alternative PCB and ECU as he sees fit.
I am hoping to be to be leaving him again with grin on my face (last time it was after a 160) and then putting a thick black line undr this thread!

I will let you know the outcome.

Tony

Excellent, it will be good to finally confirm what the fault is as far as the fan speed goes. Then it is just a matter of seeing how the rest of the cooling system performs.

[rovertone]

The mystery continues!

Phil-T4 today spent several hours testing on my fan to no avail.

Confirmed that fan runs both speeds on aircon/trinary test, it runs both speeds when forced by T4.
But when triggered by the engine coolant sensor using the spare sensor/hot air test the fan will only cut in at 97/98 and run 1st speed we tested up to a temp of 120deg., no 2nd speed.
The same test was undertaken using a different ECU to rule out any problems with my own, same result.
My fan control box was substituted for another of the same type and again exactly the same result. Phil also tried alterations to the control box wiring to no avail.
It begs the question does the 2nd fan speed work on any of the diesels with this control box, most owners would rarely see coolant temperature up high enough to have it trip in.
My grateful thanks to Phil for his efforts, and to all those who have tried to offer assistance on this thread.

Where do I go from here, try some different fans? For now I think I will have to revert to a temporary fix by putting a switch in the trinary circuit.
Is the solution out there.....who knows....

Tony

[T-Cut]

It begs the question does the 2nd fan speed work on any of the diesels with this control box

An interesting question indeed.

Spare sensors and hairdriers at the ready!

TC

[Union Wheels]

Hi followers of this thread,

looking at the centre picture in post 118 it seems that the middle relay, which normally runs the second speed in a three speed set up, is being used for the higher speed on the two speed system.

Is it possible that left hand relay is being switched by the engine temperature sensor/ECU, and this has no wires connected to it hence no second speed.

This would account for the 2 clicks, one from each relay, when " French Mikes" test is applied.

I mention this, as information on components being omitted on the control PCB in certain instances has been stated in previous posts. This would seem to suggest that the PCB went through a process of evolution when three speeders were discontinued.
"Jules" also says that some boards seem to work and others don't.

Am I just clutching at straws? Pete.

[RayH]

Hi followers of this thread,

looking at the centre picture in post 118 it seems that the middle relay, which normally runs the second speed in a three speed set up, is being used for the higher speed on the two speed system.

Is it possible that left hand relay is being switched by the engine temperature sensor/ECU, and this has no wires connected to it hence no second speed.

This would account for the 2 clicks, one from each relay, when " French Mikes" test is applied.

I mention this, as information on components being omitted on the control PCB in certain instances has been stated in previous posts. This would seem to suggest that the PCB went through a process of evolution when three speeders were discontinued.
"Jules" also says that some boards seem to work and others don't.

Am I just clutching at straws? Pete.

I think you may be clutching at straws Pete :D
If that were the case then Tony would have no high speed under any condition but he does have it with the trinary test.

[Union Wheels]

Hi RayH, I think you are right.

It needs a scope connecting to the input tag on the control panel and the pulse width monitoring, if pulse is present then voltage checks at potential divider and follow circuit with checks until the fault is discovered.

If pulse is low or missing then check wiring at connectors for corrosion or damaged wires (sometimes insulation breaks down and verdigris eats into wires turning then into resistors).

Can't think of anything else.

Pete.

[rovertone]

I think Phil was also thinking along similar lines to Pete and he did carry out various tests across relays etc. If he picks up on the thread he may expand.

[RayH]

Hi RayH, I think you are right.

It needs a scope connecting to the input tag on the control panel and the pulse width monitoring, if pulse is present then voltage checks at potential divider and follow circuit with checks until the fault is discovered.

If pulse is low or missing then check wiring at connectors for corrosion or damaged wires (sometimes insulation breaks down and verdigris eats into wires turning then into resistors).

Can't of anything else.

Pete.

That was my earlier thinking, which is why I asked Tony to check the resistance between the ECU and fan control, but from what Phil has said that appears to be irrelevant anyway as T4 switches it on. :shrug:

[Jules]

In due course I will duplicate the tests I did in the link mentioned in post 179 using a variable resistor.

But as far I remember my tests "simulating" the various coolant temp fan cut in speeds did in fact trigger all the different fan speeds.

I would have thought many hot country owners would have complained about overheating before now if diesels didn't use high speed for extra engine cooling !!

[rovertone]

Jules,
I will listen out for when you have carried out your tests, if you find the solution I'll no doubt be taking a trip to North Wales. I am due to head off to Portugal again in a couple of weeks and haven't made my mind up yet whether to take the van, either way I hope to put a temporary switch in.
Good point re owners in hot climes.
Tony

[Union Wheels]

Hi rovertone,
you said previously that you had a good rover parts specialist near you with lots of parts. Why not get a working 3 speed fan from him (after all that was the original configuration) and see if that works. He may let you have it on the basis that if it does not work you can take it back.

If it does work and you are then concerned about the longevity of the motor, do my modification (link in my signature) you already have the resistor and bracket on your 2 speed set up.

Cheers, Pete.

[Phil-T4]

The strange thing with that is I tried a 4 wire 3 speed control box and rewired the car back to how the original configuration was. Even then only 2 relays in the control box were energised via the pwm.
At idle we had 3.34v, low speed was at 2.75, medium was 1.75(?) and high was 0.40v.

[FrenchMike]

The strange thing with that is I tried a 4 wire 3 speed control box and rewired the car back to how the original configuration was. Even then only 2 relays in the control box were energised via the pwm.
At idle we had 3.34v, low speed was at 2.75, medium was 1.75(?) and high was 0.40v.

Hi Phil,the most significant voltage is across C9.

See what i got on the 3 speed PCB i have tested.(just when the relay energise)

Low=1.6 volt
Med=5 volts
High=8 volts

51777

Mike

[rovertone]

Hi rovertone,
you said previously that you had a good rover parts specialist near you with lots of parts. Why not get a working 3 speed fan from him (after all that was the original configuration) and see if that works. He may let you have it on the basis that if it does not work you can take it back.

If it does work and you are then concerned about the longevity of the motor, do my modification (link in my signature) you already have the resistor and bracket on your 2 speed set up.

Cheers, Pete.
Hi Pete,
I went down on Monday, I think he must have everything but fans, he's breaking all the time so I will be keeping in touch. I am going in next week anyway to get a few bits for spares to take with me on my travels so will sound him out on your 'sale or return' idea, thanks for that.
Tony

[Jules]

I've yet to see a second hand 3 speeder which works on all speeds :eek:

[RayH]

Perhaps you don't Simon, but I do. Rovertone is getting there with his issue, but peripheral questions were raised and I think they're interesting. You don't have to join in or comment if they don't interest you. A lost sensor signal while driving is well within the realm of possibility. I'd like to know what happens next. The heat soak connection may or may not exist, but any info is useful. We've had two different answers to the run-on period (three minutes and ten minutes), so what's correct? You'll not find the answer in RAVE.

TC

Okay, disconnected coolant temp sensor on mine today.
Turn ignition on and fan runs at high speed, yes it definitely was high speed.
Turn ignition off and fan cuts out after 3 minutes.

[SD1too]

Turn ignition on and fan runs at high speed, yes it definitely was high speed.
Ray,

It's good to have confirmation of what happens when the coolant temperature sensor gives an 'invalid' reading. However, T-Cut also refers to what he calls the "heat soak" condition. On the petrol engines, this is when the engine is stopped and the coolant temperature is above a certain threshold with a fitted and working sensor. The radiator fan then runs on for a pre-determined length of time. There is no mention of this feature in RAVE for the diesel, and the conditions would be difficult to reproduce, but if you can think of a way I would be as interested as T-Cut to know the answer.

Simon

[RayH]

Ray,

It's good to have confirmation of what happens when the coolant temperature sensor gives an 'invalid' reading. However, T-Cut also refers to what he calls the "heat soak" condition. On the petrol engines, this is when the engine is stopped and the coolant temperature is above a certain threshold with a fitted and working sensor. The radiator fan then runs on for a pre-determined length of time. There is no mention of this feature in RAVE for the diesel, and the conditions would be difficult to reproduce, but if you can think of a way I would be as interested as T-Cut to know the answer.

Simon

Interesting.
Does the ECU differentiate between a disconnected sensor and one at a high temp (with the ignition off)?

[T-Cut]

Turn ignition off and fan cuts out after 3 minutes.

Thanks for doing the test.
I fear the heat soak experiment for the diesel is unlikely to be done in an intentional, controlled way. I suppose the test could be done using a spare sensor and a hotplate or a heat gun.;)

TC

[T-Cut]

Does the ECU differentiate between a disconnected sensor and one at a high temp (with the ignition off)?

That's the part two question about the fan run-on mechanism. I can't see the experiment being done directly is an intentional, controlled way. However, the spare sensor test could be applied using a heat gun, etc providing the temperature can be controlled.

I suspect, but certaninly don't know, that the heat soak run-on period will be the same as the signal lost period. I'd be surprised if the ECU could differentiate the two in the circumstances. But it's one of the unknowns and needs to be understood.

TC

[T-Cut]

However, T-Cut also refers to what he calls the "heat soak" condition.

Heat Soak: http://cjbfire.com/Heatsoak.pdf

[RayH]

That's the part two question about the fan run-on mechanism. I can't see the experiment being done directly is an intentional, controlled way. However, the spare sensor test could be applied using a heat gun, etc providing the temperature can be controlled.

I suspect, but certaninly don't know, that the heat soak run-on period will be the same as the signal lost period. I'd be surprised if the ECU could differentiate the two in the circumstances. But it's one of the unknowns and needs to be understood.

TC

Actually there is an easier way, Jules posted on it earlier, use a variable resistor! That way we can set whatever temperature we want using the OBD and maintain that after ignition switch off.

Like you I suspect that it will still be three minutes but who knows, I've been wrong before :duh:

[T-Cut]

Actually there is an easier way, Jules posted on it earlier, use a variable resistor!

So he did.
And in the interests of furthering diesel engine science, surely some investigative owner will run the test? They'd even get it named after them!

'DieselOwner's Heat Soak Fan Test' - insert your name or ID and become immortal.

TC

[RayH]

So he did.
And in the interests of furthering diesel engine science, surely some investigative owner will run the test? They'd even get it named after them!

'DieselOwner's Heat Soak Fan Test' - insert your name or ID and become immortal.

TC

I'll leave it to Jules then. Now if you'd said immoral ..... :D :getmecoat:

[T-Cut]

Now if you'd said immoral ...

The Ashley Madison Heat Soak Fan Test.
Has a nice ring to it - or perhaps not if you're discreet.

TC

[RayH]

A question for Phil-T4, MarinaBrian or any other T4 operator.

Just noticed while looking at some ZCS data that under Electrics there is a 2 speed fan option.

If this is not set, could this be causing the problems that Tony is experiencing?

[Phil-T4]

I did mention this earlier ;)
The 2 speed fan option is for the KV6 only :D

[RayH]

I did mention this earlier ;)
The 2 speed fan option is for the KV6 only :D

Cheers Phil, I must have missed or forgotten that one.
Just a bit of straw grasping :D :D

[rovertone]

For those who may remember and/or contributed to this monster thread(s) I thought that I would finish the tale! The cause of the problem was the Fan Control PCB.
I am massively indebted to FrenchMike who modified a PCB with the knowledge of my problem. (Reminder: Fan 2nd speed not working when called by coolant sensor when with usual tests Trinary & T4 Forced it did)

Mike, a huge thank you.

[Arctic]

For those who may remember and/or contributed to this monster thread(s) I thought that I would finish the tale! The cause of the problem was the Fan Control PCB.
I am massively indebted to FrenchMike who modified a PCB with the knowledge of my problem. (Reminder: Fan 2nd speed not working when called by coolant sensor when with usual tests Trinary & T4 Forced it did)

Mike, a huge thank you.

Excellent news reminds me I must send Mike an FBH board over to be checked and rectified

[FrenchMike]

Excellent news reminds me I must send Mike an FBH board over to be checked and rectified

Hi Steve,

If you intend to send me a FBH PCB ,you can include some 2 speed Fan PCB's
in order i modify them.

I have set the Tony's one to

-Low speed 100 /97 deg
-High 110 / 106 deg

However all the values are possible

Cheers:xmas-smiley-019:

Mike

[Arctic]

Hi Steeve,

If you intend to send me a FBH PCB ,you can include some 2 speed Fan PCB's
in order i modify them.

I have set the Tony's one to

-Low speed 100 /97 deg
-High 110 / 106 deg

However all the values are possible

Cheers:xmas-smiley-019:

Mike

Hi Mike.
PM on it's way to you regarding the above cheers Arctic

[Union Wheels]

Hi FrenchMike,

You have another satisfied customer in "rovertone".

I wonder if you could tell us what you did to solve the problem with his fan PCB.

Cheers, Pete.

[FrenchMike]

Hi FrenchMike,

You have another satisfied customer in "rovertone".

I wonder if you could tell us what you did to solve the problem with his fan PCB.

Cheers, Pete.

Hi Pete ,

"Customer" is not the real term ;i am simply happy to share my old knowledges with everyone .:Snow:

I guess all the 2 speed PCB's have the same feature :
Their Hi speed triggers at too high temperature (around 115 deg)


I'll confirm when rovertone will send it :xmas-smiley-019:

Mike

[FrenchMike]

Happy new year to all of you .

I have tested the genuine Fan PCB Tony sent me
and found nothing wrong .

-It’s a genuine 2 speed with no faulty component

The results:

-Same test conditions as the 3 speed ,
in percent of duty cycle:
(I don’t know the exact correlation table between temp and duty cycle)

3speed genuine

Low 15%
Me 40%
High 70%

Tony' 2speed genuine

Low 15%
High 75 %


AFTER MODIFICATION for his peace of mind
(one resistor value changed)

Low 15%
High 65%

In these conditions Tony has measured:

1st Speed: On 97C Off 95C
2nd Speed On 110C Off 106C

So no Wonder that 75% could be 115 C or more ?

I have not yet received those from Steve ;I’ll confirm soon .(i guess)
If they have the same behaviour ...:shrug:

Mike