2008 535I overheat question
 

I have a 2008 535i and today I experienced an overheat problem, and I'm not sure if the issue is the thermostat or the water pump. Does anyone have any ideas? Is the water pump electrical and what fuse is it? and is there a typical problem with the thermostats?

i also have a 2008 535 and recently had to replace the electrical waterpump and thermostat. If you are getting the yellow warning light you probably lost the pump and need to replace it. The pump itself is $500, plus around $100 for the thermostat.

Is there a way to determine if the pump is bad? Can you hear it run, or feel it viberate when it runs?

I had the same problem at about 47K and it turned out to be the electric water pump....

any sign to tell?

turn the ignition on, FOOT OFF THE BRAKE PEDAL, so engine is not running! then press the accelerator for 10-15sec until you hear the water-pump running. Open the reservoir cap to see if coolant is streaming in there. caveat, if the WP is weak this test may be moot.

You also want to check for code using code-reader, at the end if WP is bad just replace the thermostat as well, same amount of labor (thermo is only ~$100).

RE: 2008 535i Overheat problem
 

Why go through the process of turning ignition on and holding gas pedal to the floor! Just start the car pull the expansion tank cap off and you can see the fluid running! Much quicker. Flows slow at first but as the engine warms the flow increases! Just my 2 cents.

It happened to me the other day, 535I 2008 with 71K, Now I asked my dealer in the my area on how much will it cost to get it replaced, it will be about $1,400-1,800. I'm thinking replacing it myself. The parts will cost me from Turner Motorsports about $600 with Thermostat. Now, does anybody here have an idea a step by step on how? Any suggestion on where to get the parts from reputable web store?

I appreciate all the help.

Thanks
Darwin

From what I read just running the engine might not flush all air out. I think the process generates more speed in the fluid or pressure. The pump is very loud when it runs in the purge process, much different than when the car is running at temp.