New belt tensioner on my '92 400E a couple months back, and I need to tighten it a bit. I know that too loose is better than too tight, but the serp belt squeaks and I need to tighten it just a little bit.

I did not install said belt tensioner and I cannot remember how to tighten. Surely it's not rocket science but couldn't find it in the search...

To adjust it you must first loosen the big bolt that holds the tensioner to the block. With that loose, the hub can rotate to change the tension. The actual adjustment is made by tightening/loosening the vertical rod with the hex top that comes up through a bracket. Power Steering bracket?

Don't forget to re-tighten the big bolt when you are done.

If you take it off completely, watch out for the spacer washer that falls from behind. It is on the big bolt, against the block.

Overtightening will ruin the tensioner. It is simply a molded rubber assembly and the tension is preload on the rubber. Over time the rubber softens and eventually comes loose from the shaft and there will be NO tension.

Hopefully, you got a new belt at the same time the tensioner was replaced.

Good Luck!

See post #2 of this thread for more indormation.
Belt tensioner question

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