2 Speed Fan Poser will my woes end! - Page 2

rovertone · 11th July 2015, 22:02

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 · 11th July 2015, 22:28

Tony,

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

Simon

rovertone · 12th July 2015, 06:19

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 · 12th July 2015, 08:37

Quote:

Originally Posted by rovertone

... 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 · 12th July 2015, 10:21

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

T-Cut · 12th July 2015, 10:56

Quote:

Originally Posted by rovertone

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 · 12th July 2015, 11:06

Quote:

Originally Posted by T-Cut

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°.

Simon

rovertone · 12th July 2015, 12:17

Quote:

Originally Posted by SD1too

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°.

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

T-Cut · 12th July 2015, 13:40

Quote:

Originally Posted by SD1too

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

Jules · 20th August 2015, 17:23

Quote:

Originally Posted by SD1too

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°.

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.

11th July 2015, 22:02	#1
rovertone Gets stuck in Rover 75 Conne SE Auto CDTi Join Date: Nov 2012 Location: Redditch Posts: 673 Thanks: 185 Thanked 135 Times in 109 Posts	2 Speed Fan Poser will my woes end! 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 __________________ 2003 Mk 1 Connie SE CDTi Auto Monogram Mirage 2/Sandstone Leather 511th CDTi out of 4744 produced 9th in Mirage 2 out of 17 produced Also 2004 Rover 25 SXi CVT, 1999 Megane Cabriolet and still missing my 800 Fastback.

11th July 2015, 22:28	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,469 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Tony, Have you got the original MGR thermostat in your diesel or have you fitted one of the in-line extra thermostats? Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

12th July 2015, 06:19	#3
rovertone Gets stuck in Rover 75 Conne SE Auto CDTi Join Date: Nov 2012 Location: Redditch Posts: 673 Thanks: 185 Thanked 135 Times in 109 Posts	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. __________________ 2003 Mk 1 Connie SE CDTi Auto Monogram Mirage 2/Sandstone Leather 511th CDTi out of 4744 produced 9th in Mirage 2 out of 17 produced Also 2004 Rover 25 SXi CVT, 1999 Megane Cabriolet and still missing my 800 Fastback.

12th July 2015, 10:21	#5
rovertone Gets stuck in Rover 75 Conne SE Auto CDTi Join Date: Nov 2012 Location: Redditch Posts: 673 Thanks: 185 Thanked 135 Times in 109 Posts	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 __________________ 2003 Mk 1 Connie SE CDTi Auto Monogram Mirage 2/Sandstone Leather 511th CDTi out of 4744 produced 9th in Mirage 2 out of 17 produced Also 2004 Rover 25 SXi CVT, 1999 Megane Cabriolet and still missing my 800 Fastback.