How do I adjust a belt tensioner?

[rallyrcr]

To start, I did search the archives, but had no luck.

I have a 1997 S320 whose alternator I needed to replace. Not the smartest thing to do, but I cut the accesory belt, and then replaced the alternator. I then attempted to install a new belt and realized that it won't fit becuase I can't figure out how to adjust the belt tensioner. Can someone please help me out!?

It's giving me a huge headache becuase I don't know what to do. Thanks in advance...Mark

[Meza]

If you look at the tensioner, there is a big bolt at the center of it facing the radiator. I think it's a 17 mm head. Loosen that bolt first. Use a breaker bar or a piece of pipe over 1/2 inch ratchet. Don't take it out. Just break it loose. The adjuster is a long piece attached to the tensioner on the back. Fit a 13 mm socket over it and loosen (CCW). This will cause the tensioner to move. Put you new belt on and then adjust with the same adjuster (CW). There is a plastic pointer on the tensioner that moves when you turn the adjuster. Adjust to about 75% of the full mark or 7 on a scale of 10. When your done, tignten that big 17 mm bolt.
Good luck.
Meza

PS. E-mail me if you need a picture of any component you're not familiar with in my description above. My procedure is based on a 2.6L 190e and Fastlane shows a similar tensioner for your car like the one in 190e, so I believe the procedure is the same for your car.

[rjcarrasquel]

This information seems to be very useful. I have a 1994 S320 and I want to change the drive belt soon. I have looked at the tensor, but I do not see any bolts at all. It would of great help for me if you could please provide with some kind of drawing. Another thing is, how do you access the tensioner from the back?. Do you access it from under the car?. If you could please provide me with this information I would be very grateful. Thank you.

[Meza]

Send me a fax # and I will send you the procedure.