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Weak belt tensioner?

2K views 2 replies 3 participants last post by  OzC36 
#1 ·
I have a recurring issue on my '95 C280 that's driving me nuts.

Has anybody had an issue with a weak tensioner on their serpentine belt? My experience with this type of tensioner has been that the pulley bearings usually fail long before the tensioner itself craps out. Not this one.
The bearing is whisper-quiet, no slop or runout, but it won't pull enough slack out of the belt. I even installed a belt that was 2" shorter to try to get more tension. It moved the pulley up, like it should have, but the belt is still too loose.
This is the earlier type with the threaded adjuster behind the tensioner. I replaced the adjuster, and everything looks kosher, but the tensioner just doesn't want to push the belt down hard enough, even with the bolt in the tensioner body loosened up and the adjuster backed out all the way. It's loose enough that I can pull the belt off the pulleys with two fingers, and the belt is even shorter than the OE one. That shouldn't happen.

The tensioner is a little spendy, but I don't mind as long as it fixes the problem. I just don't want to replace an expensive part and have the same issue.
 
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