Diesel thermostat definative answer

[Synchromesh]

Originally Posted by Jules

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

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.

[HarryM1BYT]

Originally Posted by Synchromesh

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.

[Frank Incensed]

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!

[wuzerk]

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!

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[rossocorsa]

Originally Posted by wuzerk

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!

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

[wuzerk]

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

[wuzerk]

It fits in quite neatly.

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[Jules]

Great work Wuzerk!!

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

Regards
Jules

[rossocorsa]

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

[Frank Incensed]

Originally Posted by wuzerk

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!

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