This morning the Serpentine belt shredded off my 2005 CLK55 AMG Convertible
WDBTK76G15T047885.

Car is safe in driveway. I am thinking of doing repair myself.
Is getting the belt tensioner loose the hardest part? And does the tensioner stay tensioned unless pressure is applied to bolt, or does it ratchet with alternator, like my older CLK (I believe).

Any pointers on obtaining a belt diagram? Although it appears the ribbed side and flat side of belt will match each pulley, I want to make sure I have it correct.

Otherwise I will have it towed and done in shop.

 

Its an easy job.

 

Hi. For anyone interested in what it looks like for my 2005 CLK 320, here's the belt routing:

I just finished doing mine, since I luckily lost only half of its width when it shredded as I was merging onto a busy highway yesterday. Made it home with a half-width belt.

Here's what I learned after first reading about the procedure here and elsewhere, then doing it myself:

I got the belt and the automatic tensioner at the Auto Zone just down the street. Both were in stock. I replaced the tensioner just to be on the safe side; the old one looked fine.

Putting a rivet into the catch on the tensioner when replacing is NOT optional, come to find out. You CANNOT access the lower of the two mounting bolts without the tensioner locked in the open position.

You will need a 17mm socket to loosen the tensioner, preferably an extended (long) one and an E12 external torx fitting for your socket wrench. I saw elsewhere that the idler pulley (if you're replacing) might require an E10 external torx fitting. To be safe I bought both when I got the parts.

It takes a bit of force to get the tensioner to open all the way up. I'm a good size guy (6'1", 225lbs) and I had to put my back into it. It also takes a little fiddling to find where to stick your rivet or allen wrench to hold the tensioner in the open position. If you forgot to pick up a rivet (as I did) you can use an allen wrench of a similar diameter to what will come already stuck in place on your replacement part.

Once you've got the new tensioner in and you're going to put the belt in place it helps to begin with the outside long runs of the belt, doing the turns on the lower left last and the tensioner last of all.

The tensioner itself may not allow you to slip the belt on even in its locked open position. I had to give it some extra oomph with the 19mm socket to maximize the opening in order to slip on the belt.

That's it. Took me about an hour, and most of that was trying to get at the lower tensioner mounting bolt with the old tensioner unlocked. Once I figured out that part it was a snap, and I didn't have to mess with the fan shroud or the engine cover.

Hope that's helpful.