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

RHINO3K

MEMBER
2008 MERCEDES BENZ
2.0L
4 CYL
TURBO
FWD
AUTOMATIC
120,000 MILES

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

4 Replies

JOHNNY G.JR

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?

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Tuesday, November 29th, 2016 AT 5:42 PM

JOHNNY G.JR

MECHANIC
320 POSTS

Remove belt and check all pulleys for excessive run-out "play"wobble.

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Tuesday, November 29th, 2016 AT 5:44 PM

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

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Tuesday, November 29th, 2016 AT 9:39 PM

KEN L

MASTER CERTIFIED MECHANIC
47,690 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

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Thursday, December 1st, 2016 AT 12:11 PM