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1989 300SE 232k miles
1,221 Posts
Discussion Starter #1 (Edited)
Hello All,

This regards the removal of the viscous fan clutch in my 1989 300SE with 235k miles. I’ve had to take it out 3 - 4 times already, and yesterday I spent waaaay too much time trying to remember how. Because it’s pretty simple, but I forgot how to make it simple. And what specifically I did. So this is really a digital reference for me. And not necessarily every specific picture.

First, unclip the fan shroud. And move it directly over the fan. This gives best access of the front of the fan. And, for some reason, I unclip the radiator. I don’t know if there’s an advantage, and it seems to fall toward the fan getting in the way, but...

Next, my car takes an 8mm Allen bolt to remove the fan clutch. If I had one of those socket ratchet sets where the socket goes inside the ratchet, this would be super easy. But, I need to install the 8mm Allen socket and use a crescent wrench, on the Allen part.

...This will require a lot of torque, and I broke a tiny 8mm box wrench once.

Now, there’s a hole in the fan pulley, accessible from behind the pulley. This is to lock the fan, so as to break the bolt and remove it. Use the crescent wrench to turn the 8mm Allen socket counter-clockwise, until the hole is lined inside these grooves. ..There are several “filled” holes, ignore them.

Now, to make something to lock the pulley. I use an 8/32 steel Allen wrench. Something larger may fit in the hole, but there’s a limit to depth because of the shape of the pulley. This is the largest Allen wrench I can use based on that limit.

Tape the 8/32 Allen wrench to a flathead screwdriver. This is for length to access the hole.

Tape it so that the Allen wrench is on the blade side that its head faces. This is so that after sliding the Allen head into the hole, the screwdriver can be used to leverage the Allen wrench a little, helping keep the wrench in place.
Last, add a pipe to the crescent wrench on the 8mmAllen socket, for torque. Rotate this counter clockwise, making sure the Allen wrench lock stays in place (it does pretty easily) until the bolt breaks. Then simply unscrew.

And pull out the fan. Leaving the lock in place for when you reinstall.

This should be like 10 minutes. But I didn’t remember to move the shroud for best access. Or that the hole goes in the notch. Or which size Allen wrench I used for the lock. Or to tape it this specific way... So it took me over an hour. Next time, 10 minutes.
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