85c Behr T-Stat, too cool for M60?

[e34musician]

I changed lower hose, clamps, T-stat, T-stat housing and aux fan temp switch recently due to coolant leak at plastic T-stat housing. The new one is aluminium. No more leak!

I noticed that the old T-stat has BMW stamp on it (probably orginal) and the temp is 95c. But my new T-stat (Behr) is 85c. Is that OK for M60? I noticed that my temp gauge is now slightly lower than 12 o'clock when fully warmed up. It used to be slightly higher than 12 o'clock. 10c cooler, Is this a good thing for M60? Better or worst MPG?

[e34musician]

bump.

Guys, any comment at all?

[bmwrp8]

I have installed the same 85C t-stat and 80-88c auxfan temp sensor...my temp reading now is a little bit below 12oclock... works fine for me since i live in a tropical country...for me haven't noticed any change in fuel consumption...only the engine is a bit cooler:D

[e34musician]

I have installed the same 85C t-stat and 80-88c auxfan temp sensor...my temp reading now is a little bit below 12oclock... works fine for me since i live in a tropical country...for me haven't noticed any change in fuel consumption...only the engine is a bit cooler:D

I just realized my new aux fan switch is 91-99c. This doesn't match with my new T-stat. Should I be worry about this? Will the aux fan be on at all (ac off) if this is the case?

[bmwrp8]

not until you reach the certain temp.if the ac is off i think 99...but why not change your switch to 80-88?

[Boone.Msi]

ive got the 85c tstat and 80/88 degree fan switch, no problems here. Did you remove the clutch fan?

[e34musician]

ive got the 85c tstat and 80/88 degree fan switch, no problems here. Did you remove the clutch fan?

No, I did not. I did not have to remove water pump either. The U-joint socket did the trick in removing the bolts on the intake side of the t-stat housing.

I was not aware of the aux fan switch temperature when ordering it from autohuaz (there is only one type to pick - switch and t-stat). Apperently, they are not in the same range. It doesn't get too hot here in the bay area. I guess I should be OK.

I need to make sure the aux fan runs when AC is on though. Last summer, I check (with a jumper), the aux fan is only on at high speed. Is this a fuse or relay issue? If yes, where they are located? I also heard about the aux fan resistor defect ($25) that could cause this low speed failure. Do you have to remove the bumper to replace it?

Thanks for the info guys!

[632 Regal]

if you didnt chip it I would revert to the hotter stat. BMW reprogrammed the computers on most M60 cars in an attempt to help the Nikasil issue and if your running a cooler stat then in theory the engine will never run correctly. This would apply even if the block was replaced to Alusil.


I changed lower hose, clamps, T-stat, T-stat housing and aux fan temp switch recently due to coolant leak at plastic T-stat housing. The new one is aluminium. No more leak!

I noticed that the old T-stat has BMW stamp on it (probably orginal) and the temp is 95c. But my new T-stat (Behr) is 85c. Is that OK for M60? I noticed that my temp gauge is now slightly lower than 12 o'clock when fully warmed up. It used to be slightly higher than 12 o'clock. 10c cooler, Is this a good thing for M60? Better or worst MPG?

[e34musician]

hmm... this is getting interesting. Can you please elaborate more on "engine will never run correctly"? I'm pretty sure mine is a nik.

How the performance chip will help? Is it because it is programmed for lower temp or wider temp range? I hate to re-do the t-stat. It's such a mess with coolant all over the place when removing the housing.


if you didnt chip it I would revert to the hotter stat. BMW reprogrammed the computers on most M60 cars in an attempt to help the Nikasil issue and if your running a cooler stat then in theory the engine will never run correctly. This would apply even if the block was replaced to Alusil.

[632 Regal]

performance chip is designed for cooler stat. Your stock chip is waiting for the engine to warm up which it never does...in theory.


hmm... this is getting interesting. Can you please elaborate more on "engine will never run correctly"? I'm pretty sure mine is a nik.

How the performance chip will help? Is it because it is programmed for lower temp or wider temp range? I hate to re-do the t-stat. It's such a mess with coolant all over the place when removing the housing.

[Boone.Msi]

dont worry about the 80/88 degree fan switch, if you still have your clutch fan that is all you need. The only purpose of the aux fan is to cool your engine if your clutch fan cant provide enough air in stop-n-go traffic.

[e34musician]

Thanks. But what about Jeff's concern on engine operating temp (too cool) for stock DME?


dont worry about the 80/88 degree fan switch, if you still have your clutch fan that is all you need. The only purpose of the aux fan is to cool your engine if your clutch fan cant provide enough air in stop-n-go traffic.

[Boone.Msi]

not sure, mine idled rough before i did the swap. Hasnt made my engine run any better or worse. My impression was that bmw put the 95 degree tstats in the niks so that it would run hot enough to burn any sulfer that entered the cylinders. In this age sulfur is of little concern, plus i put 93 octane in the tank so i thought i would be fine. I didn't think the ecu would cause the engine to run any worse due to a 10 degree cooler engine. Thats just my opinion though, im not as experienced as the others.

I do have one question though, why is it bmw put a stock 85 degree tstat in the m60 powered 95 740i? Because that is the tstat im using...