Engine cooling fan question - BMW Forum

325iS · 09-27-2003, 09:34 AM

I'm refering to the engine cooling fan driven by the water pump -- not the electric cooling fan.

I have worked on and modified Mustangs for the past 9 years and I know that the cooling fan has a clutch that will allow it to disengage at higher RPM range. When the engine is shut off, you can do a quick check of the fan clutch by manually rotate the blades by hand and the clutch should have a slight resistence (i.e. the fan should not remain moving after you spin it hard).

While under my hood of my 325iS the other day, I tried to rotate the fan and it would not bugdge. I'm curious if the M50 fan should operate the same way as my Ford.

-Brian

325iS · 09-29-2003, 09:06 AM

ttt

This is a pretty simple question -- I figured I'd have an answer by now.

Fox · 09-29-2003, 10:15 AM

Well its pretty logical answer if you just follow the thought process. Now Im not sure if this is the answer but im just deducting from what you told.

1. The fan clutch disengages at high speeds.
2. When the car is off you cannot budge the fan.
3. answer. Your clutch is good because by spinning the fan you are trying to rotate the entire engine, crank and all. If your car is in gear this aint gonna happen.

325iS · 09-29-2003, 11:17 AM

The fan clutches that I have been familiar with use a fluid-based clutch system that will allow you to rotate them while at rest with some resistance. Even at low RPM, the fan is never fully engaged to the water pump. However, at higher RPM the clutch fully disengages and allows the fan to completely freewheel.

Thank you and I appreciate the attempt at answering my question.

If anyone has an M50 engine, take a few minutes and do this test for me. Lift your hood and locate the engine cooling fan (the one that is mounted to the water pump). With the engine off, try to rotate the fan blades by hand. Does it spin or will it not budge?

wjwbmw · 10-01-2003, 03:56 PM

Mine spins freely as it should when the engine is off. If yours doesnt something is wrong. Time to do the fan delete mod.

325iS · 10-01-2003, 04:11 PM

Quote:

Originally posted by wjwbmw@Oct 1 2003, 04:36 PM
Mine spins freely as it should when the engine is off. If yours doesnt something is wrong. Time to do the fan delete mod.

Thank you so much. I was beginning to wonder if I was going to get a response. :nice: