>>>...don't know how the clutch can make the fan spin higher than crank speed

Try holding a toy airplane out the window at 70mph - the propeller will spin like crazy. Add this force to crankshaft speed pushing a fan with slippery clutch and the fan will spin faster than crankshaft speed. Otherwise what's the point in having a fan clutch at all??

Nobody knows why the little 4 cyl D was not originally equipped with fan clutch that was standard on 5 and 6 cyl cars. Maybe MB thought their slowest car wouldnt go fast enough to make a difference (:lol:)

I guess its a matter of personal preferrence whether you'd rather rely on a sensor or toggle switch to activate the auxiliary electric fan. Personally, I've been boning the car of as many ridiculous or unreliable features as possible. Vacuum central locking system and cruise control are also in the garbage heap after they broke and threatened me with huge repair bills that rival the mortgage on my home. Another idiot feature in the trash is rubber trunk liners that trap water underneath.

None of the sophisticated features of modern cars interest me at all. Thats what keeps me hooked on Vintage MB's....... i hate anything that doesnt make sense to a dummy like me and right now my engine block has only 2 active electrical hookups: 1) glow plug wire 2) temp guage sensor.

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'80 300SD/ w116
'79 240D 4-spd
'71 750cc Guzzi

previously owned:

'83 240D 4-spd
'77 280SEL 4-spd
'74 280/8
'72 250/8
'65 220Sb 4-spd
'63 220Sb 4-spd
'63 190c 4-spd
'61 220Sb 4-spd
'60 190b 4-spd