Mechanics

NO HEAT

1998 BMW 540i • V8 2WD Automatic • 118,000 miles

1998 BMW 540i and the heater blows out cold air and the car is starting to overheat with around 118,000 miles. The heater will work from time to time but for no apparent reason. Typically it is now just blowing out cold air even when I set the internal temp to 90
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Robertharney
January 11, 2011.




Start by replacing the thermostat and see what happens-

Tiny
Rasmataz
Jan 11, 2011.
This seems like two separate issues to me. The overheating and the heater not working. The heater not working could be most likely caused by a cranky heater control valve, the overheating might take some searching to get to the root cause. When does it overheat, in traffic on a warm day? Or does it seem to just be running warm all the time? Rasmataz is correct for having the thermostat be the culprit, but lets see if it can stand alone so we can get to the root cause before we just start throwing parts at it. I am running around a bit today and will try to check in in a couple of hours.

Dr. Hagerty
Jan 11, 2011.
Thanks guys. I just noticed the thermostat starting to change today. It would start rising if I were idle. I am in Chicago and it is 20 degrees outside. Once the car started moving then the temp would go back to normal. Now I have not yet replaced the water pump which is to be changed at 100K and I am at 118K. It is crazy the heater does not work. However, the heater will work from time to time.

Tiny
Robertharney
Jan 11, 2011.
Hagerty is right most likely you have a bad heater control valve, heater control valve is a key component. As far as overheating goes def check to see if thermostat is opening up. Ill be intersted to know what did you find out.

Tiny
Bmwtechwaqas
Jan 11, 2011.
Me too!

Dr. Hagerty
Jan 11, 2011.
Hey Doc you got ( SideKick ) time for me to demarry you buddy-this year is going good huh! Adios amigo esta lawago-

Tiny
Rasmataz
Jan 11, 2011.
Nothin but LOVE right back at ya
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Dr. Hagerty
Jan 12, 2011.

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