Recently a friend and I changed the cogged v belt on my 1992 300-E. We were preplexed when the belt tensioner did not give way as much as we felt it might to remove the old belt. Reassembly was even more preplexing as the pointer was movable with a finger , should not this pointer be locked after tighting.

Everthing ran ok untill the next morning when I heard a loud squeel from the engine at start up, that disapated and was only breif. Yesterday morning I went to check the car again only to fine the noise presisted and the tension on the belt had releived it self.

With only 36,000 miles on this car can a belt tensioner go that soon? What is involved with replacing a new belt tensioner and should I expect to replace any other parts that go with it?
I would like to do the work this weekend any help would be appreciated!
Bob Geco
1992 300-E sportline orginal

On this tensioner what you need to do is loosen the center bolt on the tensioner and then adjust the tension through 13mm adjustment bolt. Once proper tension is reached retighten the center bolt that holds the actual tensioner in place. This bolt is 19mm. Hope this helps just went through this myself this week. If the tensioner is bad you have to remove three pulleys before the tensioner assembly can come out.

As gvanhouten indicated, you need to tension with the adjustment bolt. It sounds like your tensioner is toast.

I am quite confused that your 300E has a cogged V Belt. Every 300E I've ever seen has a micro groove serpentine belt.

Have a great day,