Serpentine Belt Issue it keeps jumping a tooth even after replacing the belt

2008 MERCEDES BENZ
120,000 MILES • 2.0L • 4 CYL • TURBO • FWD • AUTOMATIC
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RHINO3K
  • MEMBER
  • 12 POSTS
Hi

The serpentine belt keeps jumping one tooth and will stay there until about six hundred miles, then the belt eventually breaks off and a new one is fitted. The process then just repeats itself.

Any suggestions?

Thanks!
Keenan
Nov 28, 2016 at 8:54 PM
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JOHNNY G.JR
  • ✓Experienced Mechanic
  • 320 POSTS
Sounds like there is an alignment issue with pulleys. Looking straight down at belt and pulleys are they plumb with each other. Was idler pulley replaced at recommended mileage interval?
Nov 29, 2016 at 9:42 AM
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JOHNNY G.JR
  • ✓Experienced Mechanic
  • 320 POSTS
Remove belt and check all pulleys for excessive run-out "play"wobble.
Nov 29, 2016 at 9:44 AM
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RHINO3K
  • MEMBER
  • 12 POSTS
I assumed it could be misaligned as well. perhaps checking the pulley where the belt did not jump a tooth might indicate that pulley to be the culprit.

I have not had a look at the idler pulley though, but will remove the belt thoroughly inspect the pulley system for play and wear.

Thanks
Nov 29, 2016 at 1:39 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,062 POSTS
Hey Rhino3k,

What usually happens is there is a problem with the belt tensioner being worn out and needs replacement.

Here is a guide that will show you what needs to be done.

https://www.2carpros.com/articles/serpentine-belt-tensioner-replacement

Please let us know happens so it will help others.

Best, Ken


Dec 1, 2016 at 4:11 AM
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