Jeep Serpinteen Belt

I've posted a pic of a serpentine belt we removed after only being on a week from a '92 Jeep. Not sure if it's a case of just super old material (on the store rack for 2 years) or what that caused it to fray and break. Couldn't find any obvious problem with bearings or pulleys as a possible cause and also wasn't sure if the last one was too tight when it went on so, how tight should a serpentine belt be when it's installed and is there any immediate tighening schedule generally recommended due to belt stretch? Any replies are greatly appreciated.

TIA

pic of the belt:

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That usually indicates the harmonic balancer has failed and has started to walk off the pulley. The balancer is down on the crank pulley.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > I've posted a pic of a serpentine belt we removed after only being on
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Mike Romain

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Will Honea

This also happens if your belt is not in the groves correctly on one of the pulleys. Check all belt alignments with the various pullyes. old john

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<ajeeperman

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cover

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cover

When the balancer fails, it usually fails slightly crooked before it spins off so you can see a wobble in it. If you put the belt on and eyeball it from the side view, the belt should look slightly skewed.

If you come at it from the bottom view, you should be able to see bits of rubber or a rubber band in the center of the balancer coming out.

Sometimes they also slip the timing mark so if you put a timing light on it, the mark on the balancer won't be in the right place. The timing is not adjustable via the distributor, so if the mark is off, it is the balancer.

It is not an unusual failure...

Mike

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Mike Romain

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cover

There is no timing adjustment on the Jeep 4.0 engine other than setting the rotor pointing 'just' past #1 post on the cap at compression stroke TDC. The computer adjusts things from there.

The distributor itself only fits in one way, it has a fitting notch on it.

This means if the timing mark is off, either the balancer has slipped or the timing chain has jumped which is almost unheard of on those engines. The last chain I saw had 200K on it or so and a new timing chain and gears had exactly the same 'slop' in degrees that the original did which means minimal wear.

Mike

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Mike Romain

As it turns out, I'm pretty sure this was the problem. The 'premium' Goodyear belt had a strange pattern to it that did not bode well with the existing grooves in the pulleys. We purchased the lesser expensive model belt which DID have a very pronounced groove track that would match those on the jeep and haven't had any problems at all. keeping our fingers crossed but believe now, that's what the issue was. Thanks again to all who replied.

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