View Full Version : Help : over heating, fan won't turn on?

07-30-2005, 12:25 AM
Hi guys, as the title says I need help!
I just did a flush and changed the water pump ,thermostat and both belts. I did use bmw coolant
I had to remove the radiator because the old waterpump was stuck (the 2 push bolts even broke!) so i have to use a slide hammer to pull the %$#@ water pump. anyhow...

after everything was put back, the car ran great for like 15 min. The temp needle started rising near the red zone. I shut off the enigne. It seems that the aux fan didn't turn on at all.

The fan should turn on when the engine was about to overheat right? what should i do / check? btw i checked the fuse for the aux fan, the fuse was ok.

Thanks in advance!!

07-30-2005, 04:47 AM
Even when Aux fan dont work, it shouldnt overheat. The aux fan hardly ever turn on. It seems like aux fan is seized but thats another problem. It shouldnt overheat in the first place. Check all the coolant and did you bleed the system?

07-30-2005, 05:24 AM
do you get heat from the heater when it's running ? If it's cold or lukewarm at idle and perhaps warms up when you step on the gas, you either need to bleed the cooling system or add more coolant. E30 if i remember correctly has a bleed screw on the thermostat housing, and the e36 has one at the coolant tank. My aux fan only comes on in extreme temperature, or when I'm using the a/c.

07-30-2005, 08:02 AM
Thanks guys for the prompt response!

Jari - The heater was cold and wasn't even warm. Is the bleed valve the pastic bolt next to the radiator cap?

mpower1226 - I think I didn't bleed the system. after flushing the old coolant I just placed the bolt back under the engine and the one under the radiator ; I then pour 50/50 coolant. I ran the enigne with the heater in full blast. The Diy that I got from the net did'nt say anything about bleeding

another thing I noticed is that the radiator seems cold , I placed my hand on top of the radiator and in the middle it wasn't warm at all. I also squeezed both of the radiator hose both were hot but no squeeshing of coolant inside.

07-31-2005, 09:35 AM
yep.. black plastic philips screw. (star shaped screwdriver needed)

07-31-2005, 11:43 AM
I agree, sounds like you might not have bled the system. Unscrew that plastic bleeder screw slowly and just a little while the car is off, to release the pressure in the rad. Open the main filling cap and check that there is enough coolant in there as well because when you open the bleeder valve, the rad or engine could end up sucking everything up meaning you need more coolant. Once the rad wont take any more coolant, tighten the bleeder screw and replace the filler cap and turn the car on to idle for a few minutes. Shut the car off and repeat all the steps again to check if it needs even more coolant (because after running the car, it might suck up even more into the block or rad), and you should be finished. You'll also be doing this to let out any leftover air bubbles in the system.

07-31-2005, 11:47 AM
Oh yeah, the aux fan is controlled by a brass temperature sensor switch on the passenger side of the radiator. If you have a new rad, make sure that the sensor is installed on that side because when you buy a new rad, there is a plug there you need to remove (may not be obvious to some). It's possible the sensor could be defective but what I think happened is, you mention the rad felt cool to the touch, and the switch only turns on when the rad is very hot, so that's the likely reason why it didn't kick in. The rad should be very hot to the touch, when running normally *th-up*

08-01-2005, 11:58 PM
I've always bled mine by opening both filler cap and bleeder valve when engine is cold. I run the engine after I have filled the rad, and keep topping it up as the engine is running. Soon the bleeder valve will start spitting coolant and I close it, let the engine warm up some more and open it again. Eventually there is no more air coming out and I close everything up. This method has worked for me well.