Hello everyone..I'm a newbie, with a belt tensioner question????
 

Just bought a pretty nice 300SEL, and it seems to have the standard issues, with the monovalve, and climate control doors, and belt tensioner..

The tensioner rod is broken.. It was that way, when I bought it..Is there any chance that there is nothing wrong with the tensioner, and I can just replace the rod, and cam, and be back in business????

I have not loosened the tensioner, but I did replace the belt..The tensioner pulley looks straight, and spins freely. There is some tension on the belt, but it doesn't seem like enough, however, the AC, and power steering, both work fine..

There is a pointer on my tensioner, but the indicator on the tensioner is not like the book describes.. The book describes 1-8 graduations, but mine only has a mark at each end, with a ramp type indicator..

Once I get all of it apart, how can I tell if the old one is bad???

Thanks in advance,
Jay..

Sounds like you need to replace the tensioner. The only time that I've seen the rod break was when the bushing inside the tensioner twisted too far(worn out).

Failure is usually when the rubber torsion bush breaks up. When you put it all back, you set the plastic pointer to one end of the triangle mark, and increase the tension till it is at the other end. Then tighten the large bolt in the middle of the tensioner assembly.

The adjuster rod breaks when either;
1. Someone tries to adjust it without first slackening the centre bolt, or,
2. It gets pulled up too far becasue the rubber has failed.