BMW V8 M62TUB Coolant Temperature Reduction using a lower temp thermostat

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well those of you hopping for an update on the 740d thermostat Ive got on order - Ive given up ! Its been on order for over a month now and communication seems to have broken down, so Ive requested a refund and have ordered one of the 80 deg kits as detailed. Great shame as it would have been nice to confirm an alternative but I just cant wait any longer.
 
Well I gave up waiting after a month for my 740d stat to turn up so i I ordered the sandwich plate unit aswell. Took a picture of the recess required for the bleed valve just to keep this thread compete ( feel free to edit your post with my pic Charlie).
Running temps are now exactly as above 92 - 93 idling 90 + - running around.

I used a 5mm drill bit to start the recess and then widened it using a small ball end grinding stone. Totall hole depth 5mm. Also used epoxy to seal the old electrical connection.
Ironicly, the postman delivered my 740 stat as I was under the bonnet despite me cancelling it and getting a refund through the credit card company as Mr bmwpartsonline refused to answer any mails.
 
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hi had my l322 for nearly 2 years now with relatively minor probs expansion tank split rocker cover gasket.needed rear bush for mot engine management light comes on when run on lpg but is not a problem had gearbox flushed filters and oil done as i tow my 2ton caravan on holidays i would like her to run cooler for trans sake i was thinking of changing stat for 80 dg i noticed some of you have taken out stat is this a good idea ? any advise would be welcome richard
 
richard1 said:
hi had my l322 for nearly 2 years now with relatively minor probs expansion tank split rocker cover gasket.needed rear bush for mot engine management light comes on when run on lpg but is not a problem had gearbox flushed filters and oil done as i tow my 2ton caravan on holidays i would like her to run cooler for trans sake i was thinking of changing stat for 80 dg i noticed some of you have taken out stat is this a good idea ? any advise would be welcome richard
Click to expand...
Not a good idea to run without a stat, it will cause rich running and increase fuel consumption, not good for the engine.
Making the engine run cooler will not necessarily lower gearbox oil temperature to any great degree.
 
Datatek said:
Not a good idea to run without a stat, it will cause rich running and increase fuel consumption, not good for the engine.
Making the engine run cooler will not necessarily lower gearbox oil temperature to any great degree.
Click to expand...

The Gearbox has a cooler that is plumbed into the engine cooling system...cooler engine = cooler gearbox oil cooler

I am running without a stat to try and trouble shoot an issue which I think is now resolved with a replacement gearbox oil cooler stat....so will be doing this mod, as I feel the 105-108degC the M62 runs at is a little excessive and leaves no head room.....I have found no running or consumption issues thus far for the last couple of months. just takes a lot longer to warm up is all!
 
Saint.V8 said:
The Gearbox has a cooler that is plumbed into the engine cooling system...cooler engine = cooler gearbox oil cooler

I am running without a stat to try and trouble shoot an issue which I think is now resolved with a replacement gearbox oil cooler stat....so will be doing this mod, as I feel the 105-108degC the M62 runs at is a little excessive and leaves no head room.....I have found no running or consumption issues thus far for the last couple of months. just takes a lot longer to warm up is all!
Click to expand...
If it takes longer to warm up, it must be running rich for longer must it not?
If the engine is eventually reaching normal temperature, there will be no effect on gearbox temperature, especially when towing 2 tonnes of caravan up a decent hill.
 
Datatek said:
If it takes longer to warm up, it must be running rich for longer must it not?
If the engine is eventually reaching normal temperature, there will be no effect on gearbox temperature, especially when towing 2 tonnes of caravan up a decent hill.
Click to expand...

Oh, don't disagree it runs richer for longer....and without the stat it runs at around 80 odd instead of 105-108

So the 25-30degC temperature delta will be cooling the gearbox oil quite well (the second law of Thermodynamics! - Entropy, the measure of a system to equalise :D:D:D)
 
Saint.V8 said:
Oh, don't disagree it runs richer for longer....and without the stat it runs at around 80 odd instead of 105-108

So the 25-30degC temperature delta will be cooling the gearbox oil quite well (the second law of Thermodynamics! - Entropy, the measure of a system to equalise :D:D:D)
Click to expand...
So, the engine is never reaching an efficient running temperature if it stays at 80C, longer gearbox life & potentially shorter engine life.
The gearbox oil cooler is thermostatically controlled is it not? If so it may well be compensating for the additional cooling and maintaining the gearbox temperature at the level decreed by the designers.
 
Datatek said:
So, the engine is never reaching an efficient running temperature if it stays at 80C, longer gearbox life & potentially shorter engine life.
The gearbox oil cooler is thermostatically controlled is it not? If so it may well be compensating for the additional cooling and maintaining the gearbox temperature at the level decreed by the designers.
Click to expand...

I agree, it should be left to run at the design temp.
 
Datatek said:
So, the engine is never reaching an efficient running temperature if it stays at 80C, longer gearbox life & potentially shorter engine life.
The gearbox oil cooler is thermostatically controlled is it not? If so it may well be compensating for the additional cooling and maintaining the gearbox temperature at the level decreed by the designers.
Click to expand...

wammers said:
I agree, it should be left to run at the design temp.
Click to expand...


With regards the gearbox cooler, yes it is thermostatically controlled I think the opening temp is around 80degC but I'd have to research that further so it could be the oil isn't really getting any appreciable cooling benefit I guess!

The M62 was run artificially high temps to improve emissions and a minor increase in efficiency.....it was only made to run higher to pass EU emission tests.

It seems without a stat the engines 'natural' operating range is mid 80's.

The M62's predecessor the M60 was run with an 88degC stat from what I can recall.....the only difference between the two engines was an electronic throttle body and single or double VANOS.....minor tweeks to the inlet manifold to prevent induction air swirling by reshaping the inlet horns.....but essentially the same engine.

So BMW elected force it to run hotter, then added a heated stat so when under load it forces the stat open further to add additional cooling it then drops to the high 80's and low 90's...once the load is off, it returns to 105-108 when cruising.....this to me would indicate that the engine works best at the lower temp for when you need to unleash the beast but then to meet emissions test, run it higher !!
 
Saint.V8 said:
With regards the gearbox cooler, yes it is thermostatically controlled I think the opening temp is around 80degC but I'd have to research that further so it could be the oil isn't really getting any appreciable cooling benefit I guess!

The M62 was run artificially high temps to improve emissions and a minor increase in efficiency.....it was only made to run higher to pass EU emission tests.

It seems without a stat the engines 'natural' operating range is mid 80's.

The M62's predecessor the M60 was run with an 88degC stat from what I can recall.....the only difference between the two engines was an electronic throttle body and single or double VANOS.....minor tweeks to the inlet manifold to prevent induction air swirling by reshaping the inlet horns.....but essentially the same engine.

So BMW elected force it to run hotter, then added a heated stat so when under load it forces the stat open further to add additional cooling it then drops to the high 80's and low 90's...once the load is off, it returns to 105-108 when cruising.....this to me would indicate that the engine works best at the lower temp for when you need to unleash the beast but then to meet emissions test, run it higher !!
Click to expand...

Doesn't make sense then to me, high load and cool is when emissions will be greatest not in the cruise when warm.
 
Charlie,
how the car running on the new stat? I'm chasing a leaking rad cap again at the moment but have ordered one of the Kits to investigate that option should it prove necessary. But I'm hoping a new genuine cap will solve the problem.
 
I thought i might add a bit to this but i did the 80 degree mod a few weeks back and thought the RR had been running better although did seem to run hotter than i thought it should at times but i didn't check the temperature.
it seemed to bleed ok, the temp gauge was central if not slightly to the left and the heater was working fine...

Ok so i took the car through a lot of traffic and noticed the oil pressure light was flickering at idle, when it was at 600 rpm, if i touched the throttle the light goes out and if i put on the AC the light goes out.

I started to think of what may be causing it and decided to check the engine temp as it would only do it after driving for some time and the display was showing it was around 106 degrees after sitting for a while or driving quickly which lead me to think the stat wasn't opening correctly and the lower pipe was cold and the upper rad hose very hot which in theory is correct ish.

I tried the bleed screw and no bubbles only coolant but when i squeezed the top or bottom hose or more so if i squeezed both together i got masses of air bubbles out of the coolant tank and it seemed to go on forever until eventually no more air came out and the coolant level was dropping a bit. i started the engine and carried on squeezing the pipes with the cap off and more air came out and the temp was sitting at 95 degrees and no oil light. i then took it for a drive and it was around 96 degrees when moving but when i stopped it would creep up towards the 103 mark and then i got a slight flicker from the oil light again.

i have parked it up at the moment as it's crimbo but i am thinking of removing the stat completely and trying it.

i didn't have to mod the housing for the bleed valve as i could see it clearly through the pipe fitting and it wasn't fouling anything but i am a bit worried i have toasted my engine or put the stat together incorrectly which will be a blow after rebuilding the bloody thing a few weeks ago. i hadnt bothered doing the mod but it blew it's top hose off the other week so i did that and the mod at the same time.:(

Any thoughts or suggestions much appreciated as always
Andy
 
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