has my fan clutch gone bad?

[schnell944]

Hey all,

My '90 535i's temp gauge has always stayed at the center mark until recently. In hot weather (85 deg) with the AC on and stopped, the temp will creep up to the mark after the center. I am not quite sure if it is because of a faulty fan.

Tonight, I sat in the car for 15-20 min and let it get hot. Temp went up the the mark after center. The fan clutched up for about 30sec (made the "bus" sound) then went off. it did not clutch up at any time before reaching the 4th mark. it also unclutched without really lowering the temp.

When I start moving again, the temp goes back to the center. Does this sound like a bad fan clutch? Truth be told, I got the present clutch from a salvage yard when I messed up my old one.

The newspaper test has been inconclusive for me. I can stop the fan, but I'm not sure if I can say it can be done easily. I suppose I'm not sure what 'easy' is in this case :p

Any insight appreciated!

[shogun]

The newspaper test is worth nothing. Not reliable.
The best test is described in detail on my website, click my website , scroll down to the bottom till you find the link to MWRENCH Ed Raether E31 website, click on whitepapers, there you find the ultimate fan clutch test.

But by the symptoms as described my you, your fan clutch must be replaced.

Or you try Toyota fluid
http://members.rennlist.com/blueshark/page11.html

[schnell944]

Hey Shogun,

I actually read the whitepaper before I went out and evaluated the fan clutch. Made all of the observations described therein and basically came to the same conclusion. I suppose it sort of threw me off that the fan clutched up and came on for 30sec, but regardless of that, it doesn't seem to be working correctly. Thanks!

[Ross]

Is the electric fan running?

[schnell944]

It doesn't have an electric fan...just the clutch operated fan.

[632 Regal]

no aux fan?? I thought they all did...
It doesn't have an electric fan...just the clutch operated fan.

[BigKriss]

i thought the aux fan was only for the a/c though


no aux fan?? I thought they all did...

[Tiger]

He didn't say if he was running AC when it happens, it he was, then I'd suspect the aux fan.

[schnell944]

The problem seems to be independent of the AC though running AC makes it worse..
sorry, thought you were referring to the main fan

[Derek A.]

On passenger side of the radiator near the top, there is a brass switch with wires coming out of it. This is the aux fan temp sensor. When the coolant temp hits xx, it turns the fan on low and then kicks it to high when it hits the next level.

Have you ever replaced the clutch fan? I noticed sitting in traffic for 10 minutes mine creeped up and its not that old. Last one I put on was like an e46 crossover unit. Not the same OEM looking unit that I had replaced before.

[mclark1983]

If your fan clutch is only engaging for 30secs and not staying on long enough to cool the engine down. It's time to replace the fan clutch. plain and simple. This is coming from someone who had the same problem prior to replacing the fan clutch. And the aux fan is use for the a/c as you guys know that and it's also used as a secondary cooling.

[schnell944]

Installed a new fan clutch today, and it worked like a charm. 90deg with AC on in traffic and the needle stayed right in the middle :) Now I have a cool looking paperweight, too.

[GoldenEagleFan]

Check this out. Replaced my fan clutch last year. Not too hard but needed to remember the nut was a left hand thread. Had a chance to visit the BMW museum in Munich last weekend. When I saw this engine I though that fan looks a lot easier to change....

[schnell944]

Check this out. Replaced my fan clutch last year. Not too hard but needed to remember the nut was a left hand thread. Had a chance to visit the BMW museum in Munich last weekend. When I saw this engine I though that fan looks a lot easier to change....

Nice! Reminiscent of BMW's aviation roots...