02 540i thermostat? help!!

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- dwilli
  
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posted
16 years ago

Thu, Mar 20, 2008 1:27 AM

Couple weeks ago I couldn't get the heater to put out any heat while idling at startup. Once i got on the highway it was ok. 2 days later i had NO heat at all and the "check cooling system level" light came on. I added about a gallon of antifreeze and it seemed ok until today. when I got where I was going I had to sit and wait...steam started coming from under the hood. I shut it off and had to leave the car for the day. Got in tonight and everything was fine until I got stuck in stop n go traffic (NYC) for an hour. The temp kept rising and the "check cooling system level" light came on again. It never reached the red zone but I was running the defrost max button and praying a lot. Once I got to the highway and could move above 40 it was fine.

Does this sound like I just need a new thermostat? 106,000 miles (mostly highway) and at 100,000 I had the system flushed.

Any ideas are appreciated.

Dale

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- RJD
  
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posted
16 years ago

Thu, Mar 20, 2008 2:26 AM

Dale, it sounds like your water pump impeller is slipping on the shaft. Don't overheat your engine. BMW engines are very sensitive to overheating. You can do major damage with what appers to be a minor cooling problem. BMW water pumps are known to have problems.

RJD

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posted
16 years ago

Thu, Mar 20, 2008 3:52 PM

Actually - the V8 pump on his car isn't known for this sort of problem. It sounds as if the car is overheating when stuck in traffic, and that could be several things..

o - Thermostat is always suspect

o - Leaks are suspect, especially on the V8 cars. Adding a gallon of coolant is pretty much a clue that there is a SERIOUS leak. FIND where the gallon of coolant disappeared to. It doesn't just "get low" - if it's low there is a LEAK.

o - Auxiliary cooling fan can be a problem on that model, and will show up when stuck in traffic. If it doesn't turn on with the AC - it's dead and needs to be replaced.

To Dale - overheating a BMW can get very expensive very fast, since the heads like to warp or crack when this happens. I would quit fooling around with it and take it to a professional and have it looked at. Certainly your choice - but if you manage to warp a head, you'll be looking for a new car rather shortly.