Overcooling + noise + loss of power = fan clutch?

[mathy]

As the subject says, my 535i is:

- running cooler than ever before (if the temp gauge goes from 10-2 o'clock it's running at about 11)
- making noise that increases with increasing engine rpm
- having a distinct loss of power when the noise is present

Also, I can actually see the fan turn faster when I'm revving the engine in neutral.

Am I correct in guessing that the fan clutch needs replacing?

[ROYinGA]

it should. You need a new one if it sounds like an airplane when hot. It should still slip some when hot.

[mathy]

It doesn't spin easily when cold (feels like the blades are going through molasses rather than air) and trust me, it sounds like an airplane. It's really the noise that's been bugging me.

Sucks because this was just replaced last year. I will do it myself this time ... the mechanic (not a BMW guy, but trustworthy) installed the shroud upside down. I thought nothing of it, but I wonder now if that contributed to the clutch failure.

[ROYinGA]

pair of pliers and whack it with a hammer. Remember reverse threads.

[a]

Except for the noise, that sounds normal. The fans do make noise when they are engaged. 11 o'clock is where mine run normally

[ROYinGA]

some when hot.

[jimoreno]

Actually, it sounds like it is doing what it is supposed to do. When the air going through the radiator gets warm enough, the liquid inside gets thicker making the fan "engage". That's the reason it makes the sound. However it should quiet down after a short while (maybe 30 seconds or so). Once the air cools down is gets thin enough to let the fan slip. If I recall correctly the test it to roll a magazine and try to stop the fan with it. If it does, it should be replaced.
And by the way, you are not "overcooling" since that would mean that your needle would never get out of the blue area. Our cars don't have a "buffered" temp indicator meaning that you see ACTUAL temperature fluctuations as they happen. Newer cars have buffered indicators so it takes a little bit longer for it to swing.
Now, if you lost power maybe you need to start looking at a couple of things. How is your MPG? Look for vacuum leaks, intake rubber bellow, etc. Also, has the proper maintenance been followed? BY this I mean, changing spark plugs, cap, rotor, filters (air, fuel), adjusting valves, etc. Maybe is time for one!
Good Luck!

[mathy]

Yeah it's definitely shot; the noise is as loud as a semi-truck.

Also, I read in the archives that failure of the fan clutch could cause power loss ... (?) There is no power loss when the engine is cold and the fan clutch is not engaged. I've been able to track the noise vs. power loss easily, since the fan noise is loud enough to be heard in the cabin, with all the windows up and sunroof closed.

[mathy]