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Basic question about Serpentine belt removal.

1K views 5 replies 4 participants last post by  503865 
#1 ·
Sorry for such a basic question but I am trying to locate the belt tensioner on a CLK550. I know this is a basic thing and I have done this job on several cars but I am having a hard time confirming the location of the tensioner and the nut that needs to be turned to move it to get the serpentine belt off. I think it is a fairly low down pulley that I cannot seem to get at from on top of the car. Would be accessible I guess with a lift but something tells me that what I am looking at is not the right pulley/not the tensioner. I have found videos for belt removal on other mercedes and they all seem to have plenty of room to work with and the tensioner is easily accessible. I find that I cannot see anything that looks like an adjusting bolt near any of the pulleys and the fan shroud makes it pretty tight quarters. Anyway, sorry for the basic/stupid question but I would love to see a picture of where the tensioner on that engine is.
 
#2 · (Edited)
Not sure about the V8 ,but on the V6 the tensioner is between the crank and the water pump pulley when following the belt travel.
Usually there is a cast in 17mm hex on the tensioner arm which allows you to fit a socket and rotate counterclockwise to relieve tension and move the belt.
Look for a pulley which is offset from the arm and you may need to feel for the hex which could be concealed below the belt.
If there is no cast in hex then use a torx bit into the centre of the pulley.
It should be accessible from the top.
 
#4 ·
If it's the same as the 350 it's a 17 mm socket and best turned with either a 24-inch plus "cheater" bar or a regular 12-inch and a length of steel gas pipe. One hand to turn, the other free to slip the belt off.

Turn it anti-clockwise when you are looking at the windshield and slip the belt off.

Easy peasy lemon squeezy, but I always take cellphone pics to help remember the belt routing first.

Worth checking all the idler pulleys for "notchy" turning as well. On both our 350 and 63 they seem to fail around 50 to 60K miles. Easy and relatively cheap to replace but a PITA if you throw a belt at 3 am. On the freeway. In the middle of nowhere. In pouring rain....
 
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