Fan clutch bolt ?

alotawatts · Post by **alotawatts** » Wed Jun 17, 2009 5:48 pm

Fan clutch bolt is reverse threaded - correct ?
# 10 -

http://www.realoem.com/bmw/showparts.do ... g=11&fg=35

T.Hanson · Post by **T.Hanson** » Thu Jun 18, 2009 10:00 am

There are two styles: First, original has a center bolt that is standard thread. ( righty, tighty.) It does insist on the hub slots, outer bushing tabs matching up and it's nice to use an air wrench ( not set to max, just tight ) to not have to fool with holding the inner hub from turning.

Yes, if not tight, one must remove the radiator to try again.

The later fan clutches use a big hex nut that reverse threads to the water pump flange. I.e., standing in the front of the car, thread the nut on by turning anti-clockwise. Pretty simple, if we turn it the wrong way it won't thread on.

This system likes the skinny wrench, hub holder tools that get used every ten years, but once is enough to be glad you have them.

alotawatts · Post by **alotawatts** » Fri Jun 19, 2009 12:45 am

Okay...so the one pictured in my REALOEM link (first post) is what you call 'the original' version. Interesting...as both my 81's and my 79 have this type......
So when did the newer type go into production ? E28's ?

Mike W. · Post by **Mike W.** » Fri Jun 19, 2009 1:44 pm

Most 80 and newer have the later style screw on fan clutch, except E23's and "some" others. Which is why they (if they know their parts) always ask what kind?

How's that for a definitive statement, LOL.

1st 5er · Post by **1st 5er** » Fri Jun 19, 2009 7:37 pm

My 79 has the old style.

Is there anything wrong with welding a plate to #8 and bolting across the fan and clutch assembly, thus disabling the clutch, and having the fan run at engine speed?

Would it be noisy, etc?

Mike W. · Post by **Mike W.** » Fri Jun 19, 2009 7:57 pm

swatterssr wrote:My 79 has the old style.

Is there anything wrong with welding a plate to #8 and bolting across the fan and clutch assembly, thus disabling the clutch, and having the fan run at engine speed?

Would it be noisy, etc?

I would sooner clean everything with carb cleaner and epoxy it to try and keep everything straight. I've had seized ones, I might still have one if you really want me to look, and at least with the 8 blade fan I didn't notice any extra noise. Might be my less than perfect ears, but they were better in those days

Remember you don't want any runout, that puts an extra load on the water pump and it's bearings. The 9 blade fan seems to move more air and will make noise.

All of which is a long way of saying I wouldn't do it.

1st 5er · Post by **1st 5er** » Fri Jun 19, 2009 8:10 pm

No issues presently that warrant it, just wondering.

Pierre · Post by **Pierre** » Sun Jun 21, 2009 4:13 pm

swatterssr wrote:My 79 has the old style.

Is there anything wrong with welding a plate to #8 and bolting across the fan and clutch assembly, thus disabling the clutch, and having the fan run at engine speed?

Would it be noisy, etc?

Why would you?
If it's cost issue, (early fan clutches are much more expensive than the late ones) the conversion is easy.

If your can is running warm, you have other issues you need to address. If you want additional cooling, you can wire the electric fan to run early or override it with a manual switch.

Fixing the fan clutch to run full speed with the engine has negative effects.
1. Noise. It's significant.
2. Too much cooling when you don't need it. It will take longer to get the car warm, running in warm-up mode longer. More fuel usage and more wear on the engine and more pollution.
3. More constant drag on the engine, i.e. loss of power and additional fuel consumption.

Not recommended.

1st 5er · Post by **1st 5er** » Sun Jun 21, 2009 7:22 pm

swatterssr wrote:No issues presently that warrant it, just wondering.