M30 Fan clutch.

[aston_jag_tech]

Installed a new fan clutch from Sachs due to old one free wheeling while hot.

New fan clutch free spins also. Am I missing something or did I buy a faulty fan clutch again?

-Scott

[shogun]

http://www.mwrench.com/Whitepapers/FanClutchtest.pdf

[aston_jag_tech]

http://www.mwrench.com/Whitepapers/FanClutchtest.pdf

Thanks.

The clutch is defective.

[shogun]

The above instruction to check the fan clutch by MWrench is in my opinion the best testing method I have ever seen. Forget about these funny rolled newspaper tests.

[Claude]

The above instruction to check the fan clutch by MWrench is in my opinion the best testing method I have ever seen. Forget about these funny rolled newspaper tests.

What component of those fan clutch break over time ? was is the weak link ? they don't seems to be very reliables

[winfred]

if the center of the radiator is not getting hot the clutch will not do anything but freewheel, the clutch is thermally operated but if the thermostat is defective or the radiator is clogged or the system is air locked the radiator is not going to get hot and kick the clutch in (or activate the electric fan) even if the engine is overheating

[aston_jag_tech]

So I talked with Bavauto abotu the fan clutch and through their tests of testing it is ok..

I pull the system in a vacuum, and refilled...bled it and everything, I made sure my bypass line is open and the vent line is open. too.

I then was thinking what if the headgasket I did was done incorrectly so I did a block test... All is fine, did not change from Blue to Yellow.

But while running the car and squeezing the hand pump I was getting any bubbles anymore. The squeeze ball was stuck and was being pulled by vacuum.

Only thing I could think of causing a vacuum is a faulty T-Stat or some other blockage in the cooling system. But my upper and lower rad hoses are hot while car was above normal temp.

Im getting pretty fed up with this I must say...most people ask why I still have the car, and its because I love it.



To answer your question about the fan clutch....The last one I had was about 1 year old and to my knowledge just freewheeled while hot and was defective. Or maybe my cooling system has another unknown, rare issue and the fan clutches are ok.

Thanks for the responses guys...

[shogun]

What component of those fan clutch break over time ? was is the weak link ? they don't seems to be very reliables

Usually they last very long. In one of my 750 I still have the original one from 1988.
The fan drive clutch is a fluid coupling containing silicone oil. Fan speed is regulated by the torque carrying capacity of silicone oil. Fan speed increases with a rise in temperature and decreases as temperature goes down. The more silicone oil in the coupling, the greater the fan speed. The less silicone oil, the slower the fan speed. A heat-sensitive, bi-metal spring connected to an opening plate regulates the amount of silicone oil entering the coupling.

You can also add new oil, see here from the Porsche info
http://members.rennlist.com/blueshark/page11.html
http://bmwe32.masscom.net/johan/fan_...an_clutch.html

[Claude]

Usually they last very long. In one of my 750 I still have the original one from 1988.
The fan drive clutch is a fluid coupling containing silicone oil. Fan speed is regulated by the torque carrying capacity of silicone oil. Fan speed increases with a rise in temperature and decreases as temperature goes down. The more silicone oil in the coupling, the greater the fan speed. The less silicone oil, the slower the fan speed. A heat-sensitive, bi-metal spring connected to an opening plate regulates the amount of silicone oil entering the coupling.

You can also add new oil, see here from the Porsche info
http://members.rennlist.com/blueshark/page11.html
http://bmwe32.masscom.net/johan/fan_...an_clutch.html

As always Shogun you have top notch infos and pictures to support what you said, thanks very much for that. So according to those references i would think that as long as the fan clutch keep is oil and the bimetal blade stay clean (not to clogged) the fan clutch should work properly. Also an oil leak should be easely notice (oil spilled over the fan blades when it happen).

[winfred]

the leak is slow and usually absorbed by the dust passing though/around the front of the engine, generally 10 years or more for the factory unit and less for aftermarket units i find for life span, the behr unit costs more but is much better then the sachs, theres a really cheap after market japanese looking clutch with a spiral spring in the front that is failure prone, a good portion of them lock up and explode the fan blade and others crap with no real leak or other sign