Overheating M20

[uscharalph]

Last Friday my 1989 E34 525i (M20) overheated in stop & go traffic. I let it cool and got more coolant in the system. Got it to a nearby mechanic. Monday morning they got the system full (Hopefully) and bled it (Hopefully). They the pressure checked it for 3 or 4 hours. No leaks. I've got a new thermostat in the sytem. He recommended that I change the fan clutch ($140.00 + labor). I checked with my brother and he told me to call BMA for the part (>$69.00 shipped). The mechanic didn't charge me for the pressure testing. We installled the fan clutch tonight. I'm thinking of doing a power flush and maybe a new water pump. I guess I just take it a step at a time, unless there are any suggestions.

[pong]

checking the cylinder head gasket might help... mine got toasted when the engine overheated...

[Kalevera]

The thermostat still may (although it's a very unlikely MAY) be the problem. My car was overheating after installing a new Vernet tstat. After spending a week checking everything but it, I pulled it out and tested it (bring water to a boil in a pot with the tstat in it, observe what it does). I discovered that, although the tstat worked, I'd incorrectly placed a rubber gasket, which was preventing the tstat from opening (this was an m30 specific problem, though, IIRC).

Before you spend the money on a fan clutch, see if it's "walking"/has normal resistance when cold. Also, check the aux fan and confirm that the sensor is working.

How badly did the car overheat? Waaay above the 3/4 mark or ?

best, whit

[uscharalph]

Already installed the fan clutch (Only $68.78). Didn't quite get to the red, then came out the overflow. This morning was good, the real test will be this afternoon, with stop n go traffic and higher outside temperature.

[uscharalph]

I'm trying to eliminate other possibilities before checking the head gasket.

[uscharalph]

Well day one with the new fan clutch was a success. I'm closely monitoring the coolant level. I'm supposed to go to Palm Springs this weekend. We'll see.