1991 500SL viscous fan screw
 

"need a little help form my friends" I live by myself and I'm tryiing to remove 8mm fan clutch bolt. any suggestions on how to keep fan pulley (water pump) from turning so I can remove fan clutch bolt. any secrets out there? THANKS IN ADVANCE!

If it's like the 6-cylinder engine, there is a trick.
The fan pulley has several small bolts, and some additional unused holes.
Look back behind those holes, at the metal housing, and you will see two raised ridges. you can stick a small rod between those ridges and directly into one of the holes in the pulley. This will lock the pulley. The rod should be about the diameter of a small screwdriver shaft, and just bend it to work.

DG

On my 420SEL, I just put pressure on the belt on the power steering pulley and I was able to loosen my fan bolts.

viscous fan screw
 

thanks for the tips....will give them a try....you guys are GREAT!!!!!!!!!!!!!!