With so many messages lately that involve questions about the radiator fan clutch slipping, I'd like to know HOW to judge how much slippage is normal -- or, how much is too much.
My concern is that all of my cars (see list below) appear to have about the same amount of "slip" when hot or cold -- they don't seem different when fully warmed up.
To test them, I reach in and give the fan blade a fast, strong push, and the blade spins a bit -- usually, the blade tip can be moved about 1 to 2" before it abruptly stops. No matter how hard you try, they never spin more than that, but it's the same hot or cold. Admittedly, my W124's blades seem to most resistance to spinning (they only move about an inch), but none of them seem any "looser" when cold than when hot.
Thus, I wonder -- if they're supposed to have more slippage when cold (or less when hot), is that little bit of slip that I find when hot (identical to cold) too much? I can't imagine them being much tighter, unless (when hot) they're not supposed to be able to turn at all -- is that the case? Then, all my clutches would seem bad. I'd appreciate your advice.
In advance, thanks.
[my cars: '84 W463/M110; '88 W201/M102; '88 W124/M103; and '90 W124/M103]

I can never tell the fan clutch condition by pushing the fan blades, unless it is very bad. I test my cars (300D and 300SD) by increasing the engine rpm when it is cold and hot (~95 degree, necessary) and listen to the fan noise. I posted detail steps in the past. Search this forum to see if you can find them.

David

PS: The fan clutch works a little more complicated (or smarter) than you think. I am not smart enough to tell if it is bad by pushing fan.

[This message has been edited by be459 (edited 07-26-2000).]

Ken, It is difficult to judge viscous clutch operation with the engine not running. The viscous clutch depends in part on centrifugal force to distribute the silicone inside the clutch housing. Check David's posts and follow his advice. If your's are OK, you should be hearing them come on line at between 90 and 95 centigrade.

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Jeff Lawrence
1987 300e
1989 300e
2000 Dodge Grand Caravan SE

The M102 engine has an electro magnectic fan. This fan free wheels just like a clutch fan but engages electrically from a thermo switch on top of the engine block. It is often mistaken for a viscous clutch system except it does not gradually get stiffer it just cuts in (100 C)and then cuts out.

yal
88 230E (W124) M102

[This message has been edited by yal (edited 07-26-2000).]