Overheating issue persists!

[Yeti Poacher]

My 94 325i has been overheating sometimes but only in stop and go traffic or accelerating from a stop light. After reading numerous threads here I decided to replace the fan clutch. It did seem bad since it easily turned about one rotation with a push when the car was cold and off but I never did the newspaper test.

After replacing the fan clutch I noticed that the temp gauge would still sometimes go up to the red but never on the highway. Same symptoms as before but less frequent (the weather has been getting colder here though). It stays there for about 10 to 15 seconds and then very quickly drops back down to the middle. Sometimes I will notice it creep up to the 3/4 mark before dropping back down. My check control also tells me to check the coolant level every time I turn off the car but it has been doing this for a very long time.

My question is this: what are the next suspect items that may cause this? The coolant level is at the specified line when cold. I have verified that my electric fan works. I replaced the water pump with one containing metal fins (not a Stewart) about two years ago when I did the VANOS.

I have actively monitored my oil for signs of coolant and seen nothing. I plan to send a sample to Blackstone for testing upon my next oil change.

Any ideas? Thanks for reading!

[mike318]

Jumper the auxilery fan to the run mode and check where it plugs in. Mine would go off and on while moving the plug. Finally used three spades.

Just a thought.........

[Yeti Poacher]

Jumper the auxilery fan to the run mode and check where it plugs in. Mine would go off and on while moving the plug. Finally used three spades.

Just a thought.........

Thanks! I will double check the connection.

[mynameisBMW]

I think this has been covered a lot of times before but if that gauge is moving to the right of center then something is wrong.

I would start with the coolant level. Make sure you have bled the system out correctly and make sure it is full to the "Kalt" line when cold.

Make sure your aux fan is coming on, check the rad for aerodynamic blockages (leaves, paper bag, etc..)

After that if you are still experiencing issues, check for leaks. Do you have to add coolant after a day/week/month? Always check the level when cold in the morning.

I don't know what options you have with pre-OBD2 cars, but see if you can get the digital numbers on the coolant temp.

Good luck.

[coolpizzadude]

It sounds like a sticky thermostat or air in the system. Did you replace the thermostat and bleed the system yet? I had an e36 with a similar issue. I bled the system and never had a problem again.

[randomy]

Sounds like the aux fan is not turning on, or thermostat is stuck closed, or air is in the system.

[Yeti Poacher]

Thank you all for the guidance!! I will go ahead and replace the thermostat and bleed the system.


I think this has been covered a lot of times before but if that gauge is moving to the right of center then something is wrong.

I would start with the coolant level. Make sure you have bled the system out correctly and make sure it is full to the "Kalt" line when cold.

Make sure your aux fan is coming on, check the rad for aerodynamic blockages (leaves, paper bag, etc..)

After that if you are still experiencing issues, check for leaks. Do you have to add coolant after a day/week/month? Always check the level when cold in the morning.

I don't know what options you have with pre-OBD2 cars, but see if you can get the digital numbers on the coolant temp.

Good luck.

I have not noticed coolant leakage. I will make sure to check these things. Thanks!

[scooper]

bleed, drive, and re-bleed again before changing parts!

[Yeti Poacher]

Thermostat was trashed! Half of it was stuck to the housing when I removed it.. No signs of oil in the old coolant. Thanks for the help.

http://thedailyyeti.files.wordpress.com/2012/10/thermostat-fail.jpg