E34 High Engine Temps - Overheating

[MarylandTim]

Hi all, I have a 1990 535i that has beening giving me some "coolant temperature" warnings. The gauge goes all the way up to the red. This only happens when I am idling for a long time in traffic. But when I start driving the temperature quickly (within 5 minutes) goes back to normal. Is this common? I don't want to overheat or damage my engine so is there something I can do preventative? Or is there something I do to stop it all together? Thanks in advance for your help.

Tim

[325isBaby]

Could be either the water pump or thermostat (most likely the T-stat stuck) when the car is in motion air rushing over the engine is cooling the engine, whereas when the car is stopped no air flow no cooling. Start with the Thermostat and water pump (mostly for good measure if it's never been changed). Good luck!!

[Torque]

I'd also check the fan clutch.
Here's how to check that: http://www.bmwe34.net/e34main/trouble/overheating.htm

[cnn]

Originally Posted by MarylandTim

Hi all, I have a 1990 535i that has beening giving me some "coolant temperature" warnings. The gauge goes all the way up to the red. This only happens when I am idling for a long time in traffic. But when I start driving the temperature quickly (within 5 minutes) goes back to normal. Is this common? I don't want to overheat or damage my engine so is there something I can do preventative? Or is there something I do to stop it all together? Thanks in advance for your help.

Tim

The fact that it is normal at cruising means the fan clutch is not keeping up at rest (idle).

I just did the whole cooling system in my E39 and posted it here:
http://bimmerboard.com/forums/posts/199986

The trick for removing fan clutch is there.

Every 80-100K, consider replacing:
- thermostat
- fan clutch, fan blades
- radiator
- hoses
- water pump (use HEPU brand if you can find it)
cn

[325isBaby]

AH, but I have had a non-circulating water pump do the exact same thing as well as a stuck closed T-stat...so don't over look!

[d3ity]

From http://www.bmwe34.net/e34main/trouble/overheating.htm

How to test the fan clutch:
Sorry guys, the newspaper test is not reliable. If the thermostat doesn't work or is slow moving, the fan clutch will fail the newspaper test and will spin freely don't even bother explaining how it is done as it is dangerous.
What you should do:
1) make sure that the thermostat is working!
2) when the car is cold, the fan clutch should turn with a small resistance and not spin freely.
3) Let the car idling and the hood not closed but down. After 5-10 min, the temperature will rise at the 1/2 mark, check that the fan is blowing a LOT of air inside the engine compartment and increase in noise level, no need to put your hands, you will feel it. If when the temperature hits the 3/4 mark, the fan is not blowing a lot of air, that means that: either the thermostat is not working or slow, or the fan clutch is bad.


Oh, damn you torque. I just looked up and saw you posted the link already...

[MarylandTim]

Thanks everybody for your help. I think it's the thermostat. I gotta take it to the dealer since I don't know how to replace it myself. I'm keeping my fingers crossed that they don't say it's like $400 or something ridiculous.

[325isBaby]

Good luck and let us know