Diesel thermostat definative answer
 

Regarding my enquiries with the UK technical manager into whether BMW ever used a hotter thermostat in the M47R engine, this is the reply I have received. This comes from the BMW development engineers in Germany.

The M47R, as we called the engine, was different to the engine for the
320D. For the Rover ( 75) and Land Rover ( Freelander) application we
used the first common rail injection system.
I went back into my documentation and have spoken to the "older"
colleagues in the development about the "cold" running engine.
We have never used different Thermostat during the life span of the
entire M47 engine ( D and R), so we do not have different thermostats to
choose from. We have introduced different thermostats for the late M57
D.
Anyway, we are sure, you cannot change the behavior of the engine with a different thermostat. At the time when we introduced the direct
injection diesel engine we had problems to get the engine to proper
working temperature, because it was so efficient.

We remember that we had big problems to get enough heat for the
passenger compartment heating, therefore we had additional heating.
Basically it would not help to get a different thermostat, because the
engine will not deliver more heat and therefore the operation
temperature of the thermostat does not matter.

I assume the cars are mostly driven in cities and will not get too much
load on the engines. There is no other way to get the engine to hotter temperatures as to put load on them ( faster driving or uphill driving !).
Sorry for this disappointing news , but if they want to play with
thermostats, then I would recommend that they will take one out of the
car and go to a spare part depot and have a look if they can find
another one from a different car, which will fit. At that time, the
supplier used mostly the same design for different car manufacturer.

BMW Group UK

So thats it boys back to the drawing board

Hmmm... So what about partially blocking off the radiator? An old trick I know, but one that has worked for me in the past on other cars? :shrug:
...

Ok
I bet the UK manager hasn't got a solution to the engine whine noise on the overrun either :shrug:

Thanks for speaking to him

Having now pondered the reply i have just sent them another note asking what cars they put the M57D in. Having regard to the last paragraph of their reply, if the thermostat manufacturer used the same design and there was a 92 degree for the M57 engine it may fit ! Perhaps somebody who has a spare / old thermostat (which I dont) could pop into the BMW dealer and compare them. mmmmmm food for thought.

Well done on getting the response, even if it's not what we were hoping for.

I'm still trying to find an alternative thermostat and I'm off to my local parts dept tomorrow, with what I've found. But BMW's reply that it would'nt make any difference doesn't bode well. This is born out by tales of good mpg obtained by members with stuck-open thermostats.

As for the motor being too (thermally) efficient, then why does it use so much diesel for the power output? As T-Cut said, it seems the cooling system is the thing that's too efficient! James' idea of restricting the air flow to the radiator has been put to me by others and currently seems the best solution. Perhaps someone can devise a way of diverting some of the air blasting through the grille into the air intake.

Anecdotal, tbh. What are you comparing it to?

There are 50 million reasons why car x will give more MPG than car y

Comparison wise, the VW Passat with the 1.9 (only 5% smaller engine...) TDI gives 50 MPG in 100 BHP guide, and 48 in the 130 BHP model... very similar to the slightly more powerful and slightly heavier Rover 75 / ZT.

Interesting!

My 2L 1993 petrol Granada seemed to be very thermally efficient. No matter how hard I drove it, I could never get it to fire up its cooling fans. One day, on an extremely hot day I did a fast 100 mile motorway run, then decided to check its cooling fans did actually work. I ran it straight into my garage, blanked the radiator up completely and left it ticking over. It took a further 30 minutes of this, before the first fan cut in.

Getting back to the 75's CDTi, I can understand that if it is very thermally efficient, it will simply take longer from cold to get up to temperature before the stat opens. The stat should then maintain the temperature by varying its width of opening. What I'm seeing via the OBD is the temperature rise up to the opening set point, the temperature then fall several degrees as the cool water starts to flow in, then rise back up to its stable running temperature. This is exactly what I have witnessed on other cars with a properly working stat and a temperature gauge which shows an accurate temperature.

I think radiator blinds fitted to the CDTi will have absolutely no effect. They were common in an era where radiators could freeze in cold weather and thermostates were not as efficient or accurately made as they are these days.

So the basic problem remains the CDTi's high thermal efficiency and its lack of waste energy to bring itself quickly up to temperature.

The simple fact that loads of CDt's are fitted with FBH, and many have a non working fan, but still failed to overheat and sieze, did point us in this direction anyway.. :shrug:

So even if we fitted higher rated thermos all that will happen is it will stay closed more. ..
...

I think its great that you got a reply from BMW, and not just a stock one, but one where engineers were spoken to.
However, I have long had doubts whether a higher rated thermostat would improve efficiency. I changed mine last year and my original temp was in the 60's (guage on 1/4). A rise of 20c, has not made much difference to mpg, if any. I doubt whether adding another 4c or more will be the answer to more efficiency. But I think its good for people to try.
Matt

HI Matt you must have other issues with your engine ancillaries, as most other members have seen typical increases of 5 MPG and some have attained the magical figure of 50 MPG once again just like when the their Cars were new.

Back in 2005/6 I often used to see 60 MPG at 60 MPH driving many fairly new 75's back from lease companies.

Our Wedgie Blue Tourer AUTO attained 51.3 MPG on a French trip back in June!

Thanks Jules,
But I have changed maf sensor, intercooler rings, filters, pcv, egr clean, etc. to try to improve matters. I can get 40mpg at 60mph on a motorway, but nowhere near 50mpg.
I also drive with a fairly light foot, and my area is not hilly.
Yet to test the injectors for leakback, so this may be an option. But I did try injector cleaner.
Matt

Mmm yes you must have less hair than me now Matt!
The performance and economy varied widely even when they were new.

Some were lively, and others were sluggish.
However recently we cured a very sluggish ZT 131 with 50K miles on it.

After much deliberation I advised the owner to go for a punt & to re purchase the XPart 131 remap CD for his VIN number.
We programmed it in and guess what ...............CURED ...like new again.


So it seems either it wasn't mapped properly from new

Or

The mapping had somehow in it's life got corrupted.
I suspect theres a few similar owners Cars driving around with the same Mapping problems

Hi Matt,I improved my mpg from 39 to 44 by having a full service,changing discs and pads all round(needed doing anyway) and renewing the maf sensor.I live in a rural area which is quite hilly and although I can`t get up to 60mph very often I am very pleased with 44mpg.Would love to take the car on a long run to see if I can improve on 44 but not possible at this time.In my opinion changing the stat won`t make any difference to mpg.
Regards
Barry:}

Matt has already changed his Stat!
Most members DO report an MPG improvement (some more than others)

I have a list of Affidavits from very happy owners somewhere if anyone wants me to list them?

Thanks again Jules,
I Dont know whether my performance is down or not. It certainly improved when I replaced the MAF sensor below 2000rpm. And I am not intersted in performance too much anyway. But improving mpg to somewhere near 40mpg would be great.
I am certaibly not saying replacing the stat did not help, but maybe 1-2mpg, so for me, hardly noticable. However the benefits with regard heat in the cab were well worth it, till I retro-fitted a new FBH this year, which made that benefit slightly redundant.
I would consider a punt with a mapping disc, as I think they are about £200 plus vat, but once I found a T4 (now ems has gone) the total cost would be near £300. Thats a lot of money to get back at 8000 miles per year.
But I will continue to search for the answer, if my car is much more uneconomical than other CDTI autos.
Matt

Ellow Jules.. I haven't had mine remapped but I have got a very nice Garmin 200w sat nav, will using that help the cars MPG any? :D

(Plzz Note:- i didn't mention biscuits).. :D

Matt.. I ave around 32 mpg locally, and the car did managed 46mpg over a 1000 mile trip when on loan to a lady friend for her annual hol touring down South. But the best I can get, even on long mway runs is around the low 40's.. But, in the cars defence, I do tend to push on a bit especially on long mway runs.. :o
...

James, but of course not more than the legal speed limit:(
Matt

IMO the BMW comment that a different (higher temp) stat will not achieve anything is contrary to observation. There are lots of people around the forum who had cool running diesels which were transformed (temp and MPG-wise) by renewing the stat. That in itself is disproves to the comment. I would also argue that the engine yields insufficient heat to raise the temp much higher. For example. if you were to restrict the flow through the thermostat, or even blank it off, do you think the engine would reach 100C and more? Try it and find out. I think the apparently redundant radiator fan would be woken up!

It may well be so that the cooling system in the diesel is simply too effective. There's a rather large volume of coolant circulating in a large cooling system. Maybe the use of a smaller radiator would be a better approach than partially blanking off the standard one?

TC

I think your right T-cut the engine is overcooled. i suppose looking at it from their point of view they need to be sure that it can comfortably cool the enging in the most extreme circumstances i.e towing a full weight trailer uphill through the sahara desert. not much good to us though driving one up round our home towns.

Agreed, but using the same radiator matrix for the diesel, V6 and K16 seems more like cost saving than engineering. IMO, the diesel is markedly over-cooled under 'normal' running conditions.

TC

Altering the cooling by replacing a non working thermo will undoubtedly make a difference as clearly the engine was designed to work with the existing thermostat working properly..

However, modifying the rad could be both time consuming and expensive, and may ultimately produce no better results than blocking part of the existing rad off with a piece of flat plastic.. :shrug:

Testing our theories is the hurdle, unless that's done we can waffle on about this forever. And personally, I don't think it's worth the risks involved.. :shrug:
...

I agree that the diesel is overcooled.Last winter mine got up to running temperature after about 6 miles,which was only around 80 degrees.This winter I intend blanking off the lower half of the rad to see if there is any improvement
Barry

I have enjoyed you lot "waffling on" about radiators and anti freeze.
I have learned a lot.
But I'm not sure what to do with all this knowledge I have acquired.

I have read some of these posts with interest, and it is dawning on me that many people have got no clue about what is going on.

If the thermostat is closed, then there is no water going to the radiator, and it doesen't matter how good or bad the radiator is. The only cooling you will have comes from the heater matrix, if it is open, and from cooling around the engine as well as from heat lost in the exhaust. That is it!

If the car in this case does not reach operating temperature, you can only block the heater and/or increase the load on the engine, as the engineer says to increase the water temperature. That is it!! it does not matter what you do to the cooling system, you can block the radiator completely, take it out or sell it! it will make no difference!
This can typically be the case on a cold day where you are cruising at a constant speed.

Obviously, a stuck thermostat in an open position will make matters worse. As you then have an amount of water being cooled because of the radiator.

So chaps, face it. If your thermostat is not faulty, (that is sticking either open or closed), it does not help to replace it with a hotter unit, if the engine is over-cooled on a cold day. The temperature of the water will not even get to the triggering temperature of a hotter thermostat, if it does not trigger the original thermostat. The only thing you will achieve is to increase the temperature of the system on hotter days, when you don't need it.

The best advice is to reduce the use of the heater, and yes, blocking the radiator might help, but not for the blocking of the radiator itself, (which will not be in operation), but for reducing the flow of cold air around the engine and in that way limiting the cooling of the block itself.

Hope this makes a bit of sense to you!

Kaiser
But what you are suggesting would make sense to me, except that even on a cold day, after about 10 miles or heavy load, the engine DOES get up to thermostat opening point of 88c.
This means that at this point the coolant starts circulating around the radiator, does it not?
All the stat does is limit the flow of coolant around the radiator at a set temp.
It might be that even with a 92c stat the engine might still not get hot enough to open this stat, but my gut feeling is that it would.
Matt

Yes, Matt, it does.
But, you have then laboured the engine to get it up to 88 degrees. Having a hotter stat in it will not have changed your experience for the first 10 miles at all!
What you would like is a car that got to that temperature after, say 2 miles, I guess?
If you want that, switch the heater off (then there is no flow of water out of the engine at all) and reduce the outside cooling of the block, by blocking some of the cold air around the block.
A piece of cardboard in front!?

You see the problem/solution?
The stat itself does not figure at all for the fisrt ten miles in your case.

Kaiser,
I agree with that.
But I dont think the whole thread was about how quickly it gets to temp. More about efficiency once up to temp.
And the BMW engineers had the answer to the slow heating problem, and fitted a FBH for this very reason.
Without the FBH, limiting the loss of heat through the matrix is a very good way to speed up the engine heating.
Matt

The experimental evidence is that diesels running at temperatures below the nominal stat setting get hotter when a new stat is fitted. There are dozens of reports on this. The statistical evidence therefore is that older stats tend to allow coolant flow to the radiator below the notional set temperature.

TC

I can answer that, Crashmarks. Using the part number on the thermostat I've found that the same one was used in the X5 3.0 D (M57 engine). I've seen one web site that shows it was used in 77 different models by various manufacturers, including Opel and Range Rover diesels! You'll note that all the other engines in which it's used seem to be bigger than ours. The original in the X5 was apparently notorious for failing. It appears that the revised thermostat still opens at 88C, though.
I believe that the thermostat alone is or was available in Europe as a separate item but my local BMW place was unable to trace the part, even with the part number. In the UK you can only get the thermostat for the M57 as a complete unit with housing and I doubt whether that would bolt straight on. This may mean that you'd have to buy the complete unit and transplant the thermostat.
I've now given up with BMW and I've turned my attention to the manufacturers, Behr and Wahler (I'm not sure if Motorrad actually make anything or whether they're just the spares arm of BMW. I'll write to them though, just in case). Behr's web site is very welcoming. They say, "What can we do for you? Give us a challenge! We will be glad to provide more information on our products". We'll see if they live up to that.
If anyone is interested in doing any dabbling, the relevant BMW part numbers are:
11 51 7 787 052
11 51 7 787 113
11 51 7 789 014
11 51 7 805 811
Someone might be able to trace the thermostat alone as a Range Rover, Opel or some other manufacturers' spare, rather than BMW's.

I REPEAT, I BELIEVE IT MAY ONLY BE THE THERMOSTAT IN THESE UNITS THAT IS THE SAME AS OURS.

Jules, I'm sending you a PM with some info which might or might not be useful

warm up tips
 

Well I have an FBH, which is nice! Everyone can significantly decrease engine warm up time just by ensuring the heater contols are set to full cold during warm up. You can feel the engine power diminish as you twist the heater control towards hot when the engine is very cold and warming up.

After reading these posts I think that most diesel owners complaining of slow warm up have a broken themostat. The thermostat is not closing properly, I have changed a thermostat before that looked ok to me but the replacement completely fixed a warm up problem that that car had.

If you have a water cooled EGR then it enables a quick warm up by using super hot exhaust temperatures to warm up the cooling water. If you remove the EGR then you get a cooler running engine.

What about fooling the EGR into opening after start up to enable super quick warm up times? Probably a bad idea, anyone tried it?

Opening the EGR early would lose you a lot of turbo power and gum up the already gummed up inlet ports, so not a good idea!

Best thing to do with the EGR is disconnect the vacuum pipe.

And any Diesel owners who wants a quick warm up time within 2 miles.......
Either retrofit an FBH kit or Buy a Petrol Car, otherwise :flog: one of these springs to mind

That makes absolute sense to me and is exactly the way I see it.

I had my old stat running at 80 to 82 replaced with a new on a week or two back. The new one is running at 88 to 90 and I now have some rough mpg figures - as near as I can tell it has gained just a slight increase, maybe 2 or 3 mpg since the swap. Towing it improved from 32mpg to 34 and solo it is doing 48 to 52.

Warm up miles seems not that much different - it took around 3 miles for the stat to open and reach 88 degrees, at ambient temperatures of 12 to 16 degrees.

Aside from the 75 CDTi, I run a VW CDTi as my works vehicle. That goes from home and is on the motorway at motorway speeds within a mile, yet doesn't start to warm the cabin until it has covered its first 8 to 10 miles in winter.

Stats
 

It is interesting that someone remarked that the only way to increase the running temperature is by doing very high speed or slogging uphill. My car was running correctly until the day I tried about 110MPH up the long hill after the Rochester M2 bridge! It has been stuck open from that day!

Been there, done that. M62 - highest motorway in England - long steep gradients. Doesn't work for me. I've demonstrated, to my own satisfaction, that the only way I can get my engine hot is with the car stationary. Need to reduce the amount of air cooling radiator/engine thus increasing temperature of coolant and (eventually) engine block.

Out of curiosity - sorry for a bit of a hijack - where should the gauge sit when driving after 15/20 minutes including climbs? I know its only a gauge, but mine sits at a 1/4 and if I press on (when I reach a dual carrigeway), it then visibly moves up to "just under" the half way mark. Back off again and it starts to fall off again (gradually). Does that mean its shot?

Hi
As highlighted on other threads re temperature gauges, running temps etc, mid point on the guage can mean anything between 75C and 115C. The readings from yours would suggest that your coolant is not getting to the temperature at which your thermostat should open and that it is therefore stuck open. To confirm the actual coolant temperature in your engine use the thread about onboard diagnostics. Basically, with ignition off press in the trip meter zeroing button and keep it pressed in whilst turning the ignition switch to position 2. Scroll through the menu that appears where your mileage details normally appear, by pressing the trip meter button at 1/2 second intervals until you come to number 19. Pause for a second to give it time to lock onto menu 19, then press again at 1/2 second intervals until you get to number 7 on that menu. The number displayed there is the temperature of your coolant. You can then start the engine and the display will show the actual coolant temperature until you turn off the ignition.
Hope this helps

If your car temp gauge doesn't get to the 9oclock position (normal) then it's a pretty safe bet your thermostat has stuck in the open position.. :o

Better get it replaced before the real cold weather gets here.. :o:(
...

Radiator Blanking
 

If your thermostat is stuck open then it should help to raise the temperature if the radiator is blanked off to some extent....fine. If your thermostat is working properly then surely, blanking off the rad will be ineffective, since the stat will just open more to control the target temperature?

I have uncertainties that the thermostats stick open, but I think what in fact happens is that the wax degrades and starts the thermostat opening sooner, and sooner. I dont think this is a mechanical problem, but a wax/chemical problem.
Matt

You are correct Matt!
Not one of them I've changed in last 2 years has stuck open. (around qty 50 !)

Now you tell me! Or, if you told me before it must be the short-term memory loss.

Interesting.. End result is the same though, engine is kept cool due to water going through the rad too early and the owner freezes.. :o heh heh..

Are 12v heaters any good? ;) :D
...

It would be interesting therefore to actually test a duff stat in heating water to see exactly what happens to it. Logically, if the duff stats are always closed when removed, then the obvious explanation is they are opening too early in the engine.

Personally, I'll be surprised if that is the result. Opening at a much lower temperature than normal doesn't come over (to me anyway) as the direct result changes in the wax.

I assume these stats are wax stats and not some other system?

TC

TC,
I believe it is wax that controls the opening.
But if it were not the wax degrading, would you be thinking that the spring tension is changing somehow?
My gut feeling is that it is more likely to be the wax.

Matt

12v heaters are quite poor, I think. But before I retro fitted a fbh to mine, I would run a small fan heater from the garage and after 15 mins it had completely defrosted all the windows from quite thick ice and made the cab toasty.
Unfortunately my extension cable would not reach to drive to work.:)
Matt

Thanks fo the tips, will have to gove the diagnostics a go! I do have one of those code readers that hooks up to a laptop and gives running info. WOnder if it'd give coolant temp.?

No, I don't go for the spring tension idea for reasons I've explained elsewhere. However, I'm not convinced about the wax either. As an organic chemist by profession, I can't see how a hydrocarbon wax can change under typical service conditions such that it dramatically reduces the opening temperature. Paraffin waxes are amongst the most stable of substances. Very difficult to alter, even using powerful chemistry. So, I'm basically undecided without more data on failed stats. That's why it's important to examine some to see how they operate in heated water. My gut feeling is a mechanical weakness somewhere in the design, but without the tests and observations, we'll probably never really know what happens to them.

TC

TC,
Yes, I would agree that proper testing would give us the answer. Unfortunately I gave my faulty stat away to another member for him to source a hotter version, which never materialised. So I am unable to help.
Matt

TC,
As I said earlier my gut feeling will be the wax, but could it be that the sealing of the wax might be at fault. Either coolant getting in to mix with the wax, or wax escaping past the seal.
Either might cause the gradual change in opening of the stat I would have thought.
Matt

The paraffin waxes used in stats is a 'narrow cut' fraction with a very narrow melting range. Different cuts have different ranges. These waxes expand dramatically when they melt, more so than water does for example. So, the solid pellet of wax is trapped behind a sealed piston. This is pushed out against the return spring pressure when the wax melts and the diaphragm valve opens. Nothing can stop that force, it's tremendous. When the wax cools, it contracts and resolidifies below the set point of the stat, so closing the valve again. The return spring ensures a nice even closure.

So, let's consider what might happen if the stat breaks down.

A. Loss of wax past the seals.
If that happened, there would be insufficient volumetric expansion to open the valve fully. Engine would overheat.

B. Spring tension is lost in some way.
The valve will open whatever the spring tension, but there will be less efficient closure. The wax may solidify without the piston fully retracting. The stat fails open. This is not observed according to Jules experiences.

C. Water gets into the wax.
Not really sure how this could happen, but wax would have to be displaced from the capsule to let water in. Water/coolant and wax have no chemical inter-reaction. Water doesn't expand much when heated, so the valve would only open partially when the residual wax melts. Result, overheated engine.

D. Can't think of it.

So, there seem to be no obvious mechanism by which the stat will open fully below the set temperature due to wax/water factor. Other possibilities are that the outer seal tends to fail allowing coolant to bypass the stat. Seems very slim possibility, but a mechanism like that would explain the observations.

TC

TC,
Thanks for the explanations.
So, if there were bypass of the outer seal, then when testing a failed stat in hot water, it would open exactly the same as a new one, wouldnt it?
I just wish I had some to test.
Matt

I would expect so. Maybe Jules will send you some to test?

TC

The Quest for an Alternative Thermostat - Update
 

Seems like half the problems with Rover engines are the result of the failure of silicone rubber seals.

I've had a response from thermostat manufacturers Behr, today. They seem to be saying that they don't supply the thermostat on its own without the housing and they don't make one with an alternative operating temperature. They've referred me to their UK distributor, Hans Motors in Birmingham. I'll send Hans Motors a copy of my original e-mail as, judging by the reply from Behr, something may have got lost in translation. I used to know someone who translated technical instructions and information from English to German and vice versa. Wish I was still in touch with him.

Most Germans speak English a lot better than a many of the English.

TC

Can't deny that TC. More probably an unwillingness to help than a lack of understanding. I hope it's a different story with Wahler, given their boast that they relish a challenge.

T-cut.. thats a good statement of cause and effect, and I would agree with you on your explanations ..... BUT my experience is different .

I have had several cars with 'waxstats' (mini/1100/maxi) and found that whenever the temp rose above normal for a little while ( I tow a small caravan), then the thermostat was bejiggered, and had to be replaced (easy jobs on those cars). It ALWAYS stuck open . My experience anyway. Are modern stats made different ?

Logic tells you if the engine doesn't warm up to the stat's setting, then it must be stuck open. That's what I always assumed. However, member Jules' replacement of dozens of diesel thermostats shows otherwise. None have been stuck open.

It seems the true cause of this mystery has still to be found.

TC

Could it be that the jammed thermo closes again when the system is drained, or when the housings fixings are being removed? i.e. stresses being relieved?
...

possibly a fail safe built in but set a bit too low? wouldn't explain a stat like mine though that works but will not hold a temp above 83C can't decide whether to bother changing it or not but mpg is a bit lame only hit 40mpg on a long run with a back wind!

There's no fail safe or anything slightly sophisticated about these stats. They have a simple sealed wax capsule containing a piston. The wax melts, expands and pushes the piston out. The valve is attached to the piston. When things cool down, the return spring ensures proper return and closure of the valve. How this device can pass coolant when below the wax setting I don't know.

What's needed is someone to check a 'failed' stat in water to see what happens to it. Does it open at too low a temperature? If so, my understanding of paraffin waxes is incomplete.

TC

"thermostat was bejiggered, and had to be replaced (easy jobs on those cars). It ALWAYS stuck open . My experience anyway. Are modern stats made different ?"

OH now then on second (and many more !) thoughts, the stat always APPEARED to be open . That was before this long discussion. Maybe the stat actually opened at a very much lower temperature than it should, due to loss of wax/water ingress due to overheating. I cant work out the results of this though , only observe that the stat didnt work properly.

All I know is that the wax stats were sold in the 60's on their property of failing safe (open) and that as the M75' stat starts to fail it means the engine runs cooler. The old style bellows type, when the bellow failed would fail to open and the car would boil up.

I will test a couple of duff stats in hot water............ when I get time!!
I've always assumed it's simply a case of the spring weakening with age.

Fitting another tomorrow & another on Thurs so another full day together with posting lots of parcels.

Jules,
That sounds great. It will be very interesting to really know what is happening to the stats.
So I assume that you will be testing some faulty stats with a new one as comparison.
Will there be a way of testing the spring tension?
Matt

Stats
 

Matt, I have tested my brand new,unfitted, stat three times and it opens at an indicated 91 C. increasing the return spring pressure made no difference as TC indicated. JULES is the key to more knowledge on this problem as he is going to check the opening temps on failed stats. Since
he has never found one stuck open or seized up then, logically, the only problem must be that the stat is opening at a lower temperature?
With regard to blanking off the radiator, it is not as simple as on most cars because the intercooler and the air con matrix,and the 2 speed fan resistor, should not be blanked off
so has anyone given thought as to the best way to do this?

I guess we're getting into brainstorming time. Maybe a flow control orifice inserted in the hose from the cylinder head? If the flow rate to the radiator was slowed down, the running temperature would increase. I could sell it on eBay.

TC

Of course the size of the orifice would need to vary, to take account of the waste energy needing to be disposed of - perhaps you could call it a thermostat :D

Mmm
And when engine needs max cooling on hot day it would boil over with a restricter in there.

Any other ideas cos the 88 deg setup is still fine IMHO!

Sort of like a stop-****? I'll get down to B&Q in the morning.:D Seriously though, nice idea.

Air gets to the AC condenser and the fan resistor through the main grille. So maybe a sliding air vent to the under-bumper grille? Similar idea to the air vents used on blocked-off chimney breasts.

Ooooh, look! My genuine name for a piece of plumbing equipment has been moderated. For anyone who can't guess what the missing word is, it starts with c and has an o another c and a k in it. But not necessarily in that order. Funny breasts wasn't moderated.

Inline stat
 

http://www.meziere.com/ps-571-0-WN0071.aspx
I think that this looks promising since it would be relatively simple to fit in the top hose? It would certainly be far simpler to change if it failed!

I'd want assurance that it failed "open", otherwise we'd end up in the same mess as our 1.8 brothers and sisters.

Inline Stat.
 

I have contacted them and will ask all the questions if all goes well. They do this item for 1 1/4" Hoses or 1 1/2". The Chevvy stats which fit are rated up to 195F which equates to 90.6 C.

Ya see what brainstorming does.

"There ain't no bad ideas when you're brainstormin'!" (Courtesy of Imagination Movers on kids' tv).

TC

Just keep on replacing them as they pack up I guess.

TC

That's what we do.
Cheaper than buying a new car:cool:

My diesel (with no FBH) was slow to warm up so I was convinced the stat was stuck open. Before the dealer warranty expired I persuaded them to fit a new stat. They asked me to buy it from Rimmers and then refunded me. I tried the new one in a pan on the kitchen hob when SWMBO was watching Corrie. I handed the new one over to the dealer and asked them to let me have the old one. The old one was not stuck open and behaved much the same as the new one when I did the hob test. The car warms up slightly quicker with the new stat but I would have been disappointed with the lack of improvement if I had paid for the new stat + labour.

with regard to economy and so on i'm not convinced the FBH helps it burns a fair bit of diesel itself which is simply pretty much wasted and it will not get the engine any hotter the stat still controls all that. Wouldn't be without it on a cold day though!!

Depends how slow you mean!
Did you do OBD test 7 checks before and after ?

I am not sure fitting a new stat makes huge differences in warm up time. Maybe a little. I think this is because of the inherant thermal efficiency of the engine, and maybe the larger mass of metal.
And the engineers knew this, and this is why they fitted a fbh, to speed up the heating.
In fact it would almost be possible to run this engine without a cooling fan in winter. I bet many have, unknowingly.:}
However, for me, the final temperature reached (88-89c) was well worth it for the extra temperature in the cab, if nothing else.
Matt

I did use OBD. The old stat and the new stat both allowed the engine to reach
88ºC. In winter when the ambient was around 0ºC the old stat needed about 8 miles to get there and the new stat needs about 6-7 miles to get there. Like everyone else appears to find, my temperature gauge tops out at 9 o'clock as the OBD rises through 75ºC. The new stat rises steadily to 88ºC whereas the old stat used to plateau before it reached 88ºC and after a mile or so it would start rising again until it topped out at 88ºC. I agree with other posters that the slow diesel warm up is due to high thermal efficiency and high heat capacity of large cast iron block. My wife's KV6 warms up after about 1.5 miles.

I always find that a normal fully working stat on a car, if you are able to catch it on the gauge, will rise up to normal, then fall a little way as the stat opens and the cold water flows in, then it will gradually rise back up to the normal temperature. My dash gauge on the 75 doesn't show this, but I do see this behaviour watching the OBD reading.

I’ve had a courteous and friendly reply from Hans Motors to the copy I faxed to them of my original query to Behr.

They say:

1. The thermostat "does not appear to be available on its own" minus the housing (although I have found evidence on Spanish web sites that it is. I find this reminiscent of the Bosch MAF sensor saga);
2. The BMW thermostat housing for the M57 engine is not compatible with the M47R (although I understand that it is the same thermostat in the housing);
3. They know of no commercially available 92C alternative to the thermostat for the M47R;
4. They can supply the PEL100570 to special order but "sadly they are not cheap" at an eye-watering £72.25 + £5 p&p + VAT.

When I had stopped laughing, I replied telling them:

1. The thermostats were available much cheaper elsewhere (which I’m sure they already knew);
2. Of the high failure rate;
3. Of the mode of failure (where the thermostat displays stuck-open symptoms, though mysteriously is apparently not stuck-open);
4. Of the labour cost of replacing the thermostat.

I asked them if their thermostats carried any sort of guarantee – though it would have to be a darned good guarantee to make me want to buy one at that price!

In-line thermostat fitted
 

Well, I went ahead with the exercise of fitting an in-line stat housing to my diesel and, so far, there have been no problems and definite improvements. I have used a Chevvy stat rated at 195F (90.5 C) and the original faulty stat is still there as there has never, so far,been any report of the stat failing in the closed position, just opening too early.
My faulty stat was producing a maximum reading of 74C on the OBD, I am now reading between 88 to 93C. Car feels more willing and I will be able to check the fuel consumption soon. During the experiment I had to change the new stat...it took 28 minutes from opening the bonnet to closing it again....result!
http://img199.imageshack.us/img199/1779/stat3vb.jpg
Uploaded with ImageShack.us

looks like the work of genius now all we need is the relevant part number

In-line stat
 

Ordered from the USA together with 3 Chevvy 195F stats.
The diesel top hose tapers down from the block end so, ideally, the stat housing would have a 1 1/2" hose fitting on one end and a 1 1/4" stub on the other end. I ordered 1 1/2" at both ends which was too tight. I do not know if they will supply the housing with different sized ends so I would go for the 1 1/4" stubs if they don't.
http://www.meziere.com/ps-572-541-wn0072.aspx

IN Line Stat
 

It fits in quite neatly.
http://img833.imageshack.us/img833/827/stat4.jpg
Uploaded with ImageShack.us

Great work Wuzerk!!

I'll stock both types from now on so members will have the choice.;)

Regards
Jules

top notch if you can sort a good price I'll certainly have one

Well Done!
 

Excellent! Good news for many members, I hope. :D
Any idea of the life expectancy of these thermostats, whether they can fail closed and, if so what the result of failure would be? :shrug:

just been wondering about coolant flow and the need for a bypass does the radiator eventually get hot with this mod?

IN line STAT
 

JULES, If you become a UK supplier that would remove half the hassle.
It is early days re testing the mod but,so far, I have done 95 miles and the OBD has only exceeded 90C twice and then it immediately dropped.
This is with a 1 mm hole drilled in the stat to prevent an air lock. I do not know if that is strictly necessary. Bearing in mind that it is now the cold season the indications so far are that the diesel is barely capable of generating enough heat even with the top hose blocked except for the
1 mm hole. As i said,to fit a new stat took 28 minutes from start to finish so if it does fail life will be a lot easier.

I think this is an excellent idea, and well done for being the one to try.
I personally think this is a better idea than trying to find a hotter stat to fit the existing housing.
So some form of bypass is not needed, with this housing, or the 1mm hole is adequate, I guess.
This looks like the housing to me:
http://www.meziere.com/ps-571-540-wn0071.aspx

Matt

Housing
 

Yes, that is the one i would recommend at the moment but I have e mailed them to ask if one could be available with a 1 1/2" inlet and a
1 1/4" outlet which would be ideal. I took the precaution of buying a new top hose in case of problems with the mod but, if you think of it it is easier to carry a suitable length of stainless pipe which will easily replace the housing in the event of trouble. If you realise that the original stat is still in place then so is the necessary by pass arrangement as designed for the engine. All you are doing is preventing flow through the rad until it reaches 90.5C which is an increase of 2.5C on the original and seems to be about as high as we can go. As to any problems when the weather is hotter 1. we have the new stat to open and 2. there is the electric cooling fan which, on my car, has NEVER been needed.
I would also point out that when you cut the top hose the coolant loss is only just over a litre.

In line stat housing
 

I have heard from the american suppliers of these housings and he says there is no problem in supplying the unit with 1 1/2" pipe at one end and
1 1/4" at the other. There is no part number for this, he just needs the request. I estimate that this would mean that a change of thermostat would take less than 10 minutes!

been pondering this one I'm no convinced that the position of the stat is correct the only bleed would seem to be from the heater circuit which will be closed in warm weather and I am not sure a hole in the stat is good enough perhaps someone more expert (Jules??) can study the diagram?

http://i724.photobucket.com/albums/w...g?t=1287527634

Sounds like it's working fine to me but with a little more time lag before the new Stat reacts.

The "bypass" as far as I can see is still in place & unchanged.
ie
1.The ball bearing valve in Old Stat.
2. I believe heater circuit is always open regardless of time of year.
(air flaps control temp as opposed to water valves)

if the heater circuit is always open then it should work perfectly as it will form the bypass for the new stat

Must say Frederick, I would like to hear your final results of your testing

In-line stat
 

It is early days of course but so far there have been no problems at all.
I will report any if they occur. The original stat is still in position so the original design is still working but when the stat opens prematurely the hot water does not reach the radiator because of my additional one. The advantage to me is that should the original stat ever stick in the closed position (never reported yet) there is no way the car could be repaired easily. If the in-line stat became faulty it could be replaced, or the whole housing replaced by a piece of stainless tube in about ten minutes.
Jules is interested in this,so, knowing him, a comprehensive quality package may be in the pipeline?

I'm interested in this new thermostat and kit when it comes available.
Could be a good time to fit before the winter hits hard.

The heater matrix is in circuit and open to flow winter or summer, heating set for hot or cold. The temperature of the air is set by air mixing flaps on all cars these days. Only the really old cars had a manually controlled valve under the bonnet to turn the water flow on and off, except I had one Vauxall which had a rather odd system of cabin temperature sensing, mechanically (bulb and mercury filled pipe) feeding back to a flow control valve. I never could get that to work properly.

I've used the above and which has leads me to ask what's the average expected running temp? I've heard 88 and 92 banded about - what's the stat rated at? Mine runs at 72degC and if I push the engine, it'll max-out at 77degC.

The running temperatures have been taken from the dash OBD.

The stat is rated at 88c and when working properly seems to do a good job of maintaining the collant at that temp.
Your readings are in common with a failing stat.
Matt

The properly working stat is rated at 88 deg C. Mine was reading 82, new car to me, so I decided to get it swapped out for a new one. It now runs at around 88 and seems to have made some small difference to the mpg. I think with a new stat you will definately see an improvement in mpg and better heat into the cab.

It might be worth waiting to see how this easy fit aftermarket stat works out longer term, before tackling the much more difficult job of fitting an OEM type.

housing plus stat
 

I just tried to email meziere enterprizes using the email address
[email protected], to request the cost of a housing plus stat shipped to the UK - but the email was rejected.

?????

In Line Stat
 

I have done all ordering on [email protected] with no problems. Don't forget to ask for 1 1/2" inlet and 1 1/4" outlet. The costs are much less than the cost of replacing the original stat and from there on the thermostat itself costs about eight dollars! So order a spare. I paid via Paypal.

Is it worth getting a few kits ordered for members who are interested? Save on p+p?

Or when do you expect to make them available Jules?

Cheers,
Rich

Ok Frederick.

As a matter of interest how much did they charge you for a housing plus stat shipped to the UK in dollars??

It seems the way to go, since to replace the original is such an awful costly job

In line stat
 

Paypals record shows 112.02 dollars. this was for the housing plus 3 stats. The conversion was done by Paypal and I think it was about £76.
I also had to pay £12.00 VAT when it arrived. Well worth it in my opinion and I have still had no problems with the installation. The postage alone was around 29 dollars! The warm up time is obviously quicker than before although the system still struggles to reach 90 C but with the heater on 'ECON'
and the air flow on 'feet and screen' I can feel the warmth within 1/2 a mile and my feet are toasty within two miles. That was after scraping the ice off the windscreen this morning.

Update
 

No problems with the in-line 'stat installation and,quite frankly, I don't expect any. If the original 'stat stuck in the closed position then it would have to be replaced and nothing i have done has altered that fact. What it has altered is that if you have a 'stat which opens too early then you can just ignore it and leave it in situ because the temperature will still be controlled by the new,higher rated one which is fitted closer to the radiator in an easily accessible position. If the new unit did fail it would only be important if it stuck closed. In that case the in-line stat housing could be removed completely by undoing two hose clips and replacing with a suitable piece of pipe. I say use pipe because the housing has two spanner fittings which are approximately 2 1/2" across the flats! Not a size you are likely to be carrying in the boot if you wanted to fit another
Thermostat by the roadside. What a thought....change a diesel 75 thermostat in minutes by the roadside!
The OBD running temperatures are from 87C to 93C and are entirely dependent on the load on the engine.

Any chance of a how to etc happening soon?

I think its as simple as cut a small section out of the top hose, put the housing in and seal with jubilee clips. Top up. About 10 mins, I would guess. Or am I being too simplistic here?
Matt

Well done on this Wuzerk.
Like you say the worst that can happen is the new one fails closed, even then I believe there would be plenty of warning
ie visible steam, then an even bigger delay before any serious damage to the hot lump.

28 mins Wuzerk states !

And this applies equally to ALL thermostats in ALL engines. I've yet to read of it happening on these cars and the Americal unit is no different. I think worrying about the possibility of a stuck shut stat is being over cautious about applying the mod. So far it looks like a great advance in getting the diesel closer to the optimum band in both heating efficiency and fuel economy. If I had a diesel, I'd be odering the parts already. Personally, I think I'd now try it without the pin hole.

TC

In-Line Stat.
 

Yes, it is rare that such a useful modification is so easy to fit once you have summoned the nerve to cut the pipe! Points to note:
1.Use plastic sheet to prevent water hitting the Alternator when you cut the pipe.
2.It is probably sensible to remove the undertray because otherwise the water sits there and, in the middle of your test run, you suddenly see steam wafting from the grill causing panic until you realise what is happening. OR, follow Jules advice (below) re lowering the expansion tank.
3. Be sure to install the Thermostat the right way round. The wax housing, with '195' stamped on it, should face the engine block.
4.It is hard to fit the 1 1/2" stub into the sawn pipe on the engine block
side but washing up liquid helps and, once in, it is very snug and there
is no need for any sort of support bracket.
5. The other cut should be made so that you have enough of the
straight hose pipe left to engage the end of the 'stat housing without
involving the bend in the top hose.
6. Much to my surprise, with the radiator cap fitted, I only lost just over
a litre of coolant when I cut the pipe. So have your 50/50 mix of OAT
antifreeze ready. OR follow Jules suggestion (below).
7. The spanner flats on the housing are approx. 2 1/2" across! If you
have the facilities is would be worth making up a couple of sheet metal
'spanners' to carry in the boot together with a spare Thermostat. This
would mean that, if necessary, you really could change the diesel stat
on the side of the road! If not, I would carry a suitable 4" length of tube
which would replace the entire housing if necessary. An exhaust
centre would probably supply a piece of stainless?
8. I have no idea of the reliability of the Chevrolet stat, but imagine they
know what they are doing in the USA and I am sure one of us will find
an alternative if it proves necessary.
9. For those of you with underperforming 'stats, hurry up, winter is nearly
here!
NOTE: I used a stat housing with 1 1/2" hose fittings. The diesel top hose is tapered and the 1 1/2" stub was
almost impossible to fit in the radiator side of the cut pipe. You need 1 1/2" at the engine block end and
1 1/4" at the rad end. There is no part number for this configuration but the supplier says just let him know
and that the price will be the same. The suppliers e-mail is [email protected] and the website is:
http://www.meziere.com/displaycategory.aspx?id=244,323
http://img149.imageshack.us/img149/9261/stat3.jpg
Uploaded with ImageShack.us

http://img836.imageshack.us/img836/827/stat4.jpg
Uploaded with ImageShack.us

I HAVE INCLUDED THE PICS AGAIN FOR THOSE WHO MISSED THEM EARLIER.

NOTE: There IS a well hidden bleed hole in the rim of the thermostat plate so there is no need to drill any new bleed holes. This mod gets simpler every
time I look at it!

Stat hole
 

I would agree with TC re the 1mm hole which I drilled to remove the chance of an air lock. it is worth fitting the Chevvy stat as it comes, with no hole. If an air lock does occur then i think the problem will resolve itself as soon as the 'stat opens the first time?
EDIT: There IS a well hidden hole in the thermostat valve plate so there is no need to make another one.

Trouble is it will probably cause a price hike when USA get a sudden surge of orders !! So don't all rush at once.
Another reason to have a proper Club Shop to have a bulk buy.

My advice is not to loose any coolant.
Simply loosen the 8mm bolt on the header tank and lower it next to the Battery so you can syphon off the excess, then pour it back in when job complete.

Don't forget Gents a stuck closed Stat will never be as bad as an actual water leak (hence low coolant level round the block) as there will be plenty of warning in the way of steam, without engine damage

Is anyone considering a bulk buy??

Should we see if people are interested.

Chaps
I'm waiting on a bulk quote from them.

Good to hear Jules.

Bulk buy
 

JULES, brilliant! I was a bit worried that the mod would lose you a lot of customers but now they will have the choice when they visit for buscuits!

hmm interesting ! I was about to order a bog standard stat from you Jules but I think I shall hang fire, no point in doing things the hard way is there! :}

About this little hole. Don't you need a little water flow inorder for the heat to reach the thermostat. ie if you have a long pipe full of water and only heated one end how long would it take for the other end to get hot. If the thermostat were at this end it might not open at the desired engine (block) time. But if there was a slow flow of water the other end would heat faster.

Hole
 

My initial thought when starting the experiment was that there had to be a by-pass hole in the new 'stat to prevent an air lock and to enable the hot water to reach the unit to cause it to open. I tried various sizes of holes but then discovered that there is a well hidden small hole in the Chevvy one.
No further holes have proved necessary. I have had no problems with my installation which was allowing a maximum of 74C with the old stat and now runs between 87C and 93C depending on engine load. The warm up time is not radically improved since the diesel struggles to reach temperature in the cold weather anyway but I now have warm feet which I certainly didn't have before.

if you look at the engine cooling diagram you'll see that the heater will act as a suitable bypass

As mine is running at an average of about 74c, I'll definitely be buying one of these. It looks like a straightforward mod which I'd be able to do myself... I'd certainly never attempt changing the OEM stat! if I lived closer to Jules I would have had it done by him already, but it's just too far away.

Once these go on sale I'll be first in the queue :D

Superb mod Wuzerk, congratulations ! Could you put me down for a kit please Jules, my CDTI is running at 74c !

PLEASE make a proper how-to for this... would love to do it but not overly confident :(

Been following all these thermostat threads for a year or so and have a brand new one in a box i bought last winter waiting to be fitted. This seems to be what everyone has been looking for and makes much more sense than fitting another doomed to failure stat. so waiting with interest and should be worth the extra expense :bowdown:

still got mine I bought from Jules a few months ago, it looks a pig of a job. I'm waiting......

bulk buy
 

Hi Jules I was going to order a standard stat off you but put me down for one of these moded ones please:}

Update
 

I have just done another fast 70 mile round trip and the OBD temperature reading was between 86C (long off throttle downhill),and 92C(long uphill
slog). The diesel struggles to reach the 90c temperature at this time of year but when it does the new thermostat opens and the reading drops very quickly so I do not expect any problems in the hot weather as the radiator should be well up to the job.

Great news, now waiting on Jules.

Dont suppose you have any feedback about the MPG figures yet?

Mpg
 

No, I was so busy watching the OBD temperature readings that I omitted to zero my MPG reading at my usual test run point.

I assume its better though? It seems better fuel economy is the only reason to change a faulty stat anyway!

And for cabin temperature....brrr!!!

Stat change
 

MAMASBOY, what, you don't use the heater in the Winter then? The reported improvements in mpg have not been that great. Running the engine at the intended temperatures is beneficial in many ways.

It's the wifes car, I'm barely allowed to drive the thing let alone get cold in it!

I may be confused but the original stat is rated at 88 degrees centigrate PLUS OR MINUS 5 degrees centigrate in other words the operating temperature is between 93 to 83 degrees a whole 10 degree fluctuation in operating range I just don't believe that a running temp of 77 to 78 degrees will make any significant reduction in engine performance or fuel conumption, where is the evidence for this, who has made a scientific controlled study, to take account of other variables. I am concerned that so called faulty stats are being replaced at high costs, and or being bypassed by American stats that involve chopping up hoses etc, I believe that in the abscence of hard evidence that a so called faulty stat is responsible for poor economy I would urge a wait and see strategy

All things are built to a tollerance. If all the worst case tollerances happen to appear on one car, then the car will have a worse mpg than perhaps the car built minutes after it. We are all reporting slightly different consumption figures. My own car was returning a nowhere near as good a mpg as it is now, when I first bought it. All I have done is work my way through it, checked everything and got everything working as per designed to do - including the stat which had deteriorated down to 78 deg. Each step produced some improvement and the overall effect has been worthwhile in the long term it will repay the effort and expense. I now get an extra 5 to 10% mpg.

You will not get any "official" figures, but I for one trust the guys on the forum to tell it as it is, and as far as I'm concerned if Jules is gonna sell them then they work and are worthwhile!

Plenty of evidence!
Here's some:smilie_re:
Also if you like some toasty heat in the winter, an engine running in the 70's deg range won't thaw yer feet out!

http://www.the75andztclub.co.uk/foru...d.php?p=445413

I've just paid £77.61 for the housing and two stats. I'll see what my VAT is when it lands here!
There is a part number now! WN0073.

There was no discount for a bulk order so I'm only ordering a handful for owners who want them fitted here :shrug:

How much would you charge to fit the "new" thermostat Jules?

Any chance of a how-to?

I have looked at the drawings, read the comments, and concluded it's an excellant mod... :)... Soooo .....

Can you order an inline thermo for me plzzz Jules.. (I will pop 0ver for the installation).. :}

Just gimme 48 hours to recover, I did a 12 hour drive yesterday and ache all over! ouch ouch.. lol.. :}

I have sent an email as well.. :p: :D

Belt n braces innit... :}

So what exactly do we need to order from the website to do this mod, as the only link I can see goes to a housing with 1.5" inlet and 1.5" outlet...

Evening guys

I have emailed this place http://www.specialist-components.co....dCategoryID=36 to see if they are able to produce a remote thermostat housing without the bypass pipe and a 90C thermostat. Being based in the UK it may be cheaper than getting the American one? Worth a try and I will let everyone know the outcome!