How do I loosen C320 serpentine belt tensioner?
 

My wife's 2001 C320 has a torn serpentine belt. Time to replace...now! I'd rather do it myself, but the tensioner has me puzzled. How do I loosen it in order to remove the belt. And when I retighten, what should I be doing?

Of course, what really puzzles me is how the belt got a longituditinal tear in the first place...

I think the whole tensioner pulley pivots.

I haven't done it on a 2001, but on older C's you put a socket on the head of the bolt in the center of the tensioner pulley and push it laterally to take the tension off the belt.

that is unusual how the belt got a tear,

At the center of the pulley I see a bolt (or stud) with a special head, and a nut on the stud holding the pulley in place. Do I need a special tool to go on that stud? Anyone...?

I really don't want to have to pay the dealer to do this easy job!!!

A few thngs, you have the new belt? I'll chk my 02 C240 to see if I am right in my description, but I won't be back to my computer till around 11:30 eastern time.

If you have the new belt and have Mercedes roadside assisstance come out, might they attach it?

also check out www.mbklasse.com to see if it is discussed there - you'll have to sign in - easy and quick.

But I'll go chk my C240. I'll repost in a few hour with what I found. what you are describing sound different from my 1998 C that I described in my previous post.

If it's like the W202, then all you need is to put a wrench on the nut in the middle and turn it counterclockwise. The pulley will then move inwards and take the tension off the belt.

That worked! :D Thanks, Ali.

Note to others: If you pull very hard, the nut will work loose. Just torque it down tight and try again!

The correct tool would be a E10 or female torx.
That way, you don't loosen the pully nut.

GO SEAHAWKS!!!!!!!!