Serpentine belt keeps destroying forward rib

[SubstanceP302]

Just purchased a 1025A2 last week and I have a long list of items to work through.

The current issue I’m having is with a serpentine belt. The first belt ate itself the 3rd day of driving. It shaved the forward rib partially off and the tail hacked up one of the coolant hoses. All the pulleys spun freely, and the tensioner certainly had plenty of tension. I do not have an AC system.

I replaced the ~98” belt with a Gates Micro-V K080981 (which I believe is 98 3/4”. I had to use a breaker bar to take 100% of the tension off in order to barely get the new belt on. (which makes me worry the belt was a little too short.).

after reading several other threads, I checked all of the pulleys to make sure the belt was properly aligned. The truck ran fine for the better part of the week, then last night started shaving the front rib off just like before.

this morning, I inspected the whole system and watched it run. It appears the belt is slipping forward on the crankshaft pulley when the motor is under load. Sometimes when the truck is idling or off, it will slip back on to the correct grooves. When I increase revs, it pops forward a rib.

The tensioner is also moving back-and-forth quite violently. This might just be a function of the fact the belt is missing half of the front rib. The oscillations of the tensioner seem to match up with every time that tear in the belt hits the crankshaft pulley.

The crankshaft pulley does not appear to be wobbling or out of alignment, but something is causing the belt to slip forward a rib when revs increase.

i’ve read some other threads, but they all have the opposite problem where the belt is shredding itself on the cab side.

Any thoughts?

I can’t find anybody in the Charleston area who’s willing to work on a HMMWV, so I really have no choice but to figure this out myself.

 

[TOBASH]

Look for a cracked bolt or a loose bolt or incomplete or broken brackets. Use a straight edge to make sure everything is either parallel and lined up without displacement, or at exact right angles.

 

[NDT]

I would inspect each and every pulley for nicks. I would put a straightedge on each pulley to make sure it’s not out of plane.

 

[Thunderbirds]

In my case the most upper pulley attachments bolt was lose, but still held everything in place. It also pushed the belt forward a bit due to the incorrect angle. You can barely notice the alignment when looking, but when I removed the belt it rattled around. Didn't cause my belt to tear, but enough strain on one side i replaced it.

 

[SubstanceP302]

Thanks, I’ll certainly recheck all pulley bearings, bolts, and alignment when I take this belt off.

I was just wondering if anybody had any experience specifically with the belt sliding forward on the crankshaft pulley. I didn’t know if that can be indicative of something outside the pulley system like motor mounts.

also wondering if anybody has had success with alternate aftermarket 98 inch serpentine belts. This one felt very tight going on at 98 3/4. If that’s the case, would it make it more prone to slipping when the motor moves?

 

[Thunderbirds]

Thanks, I’ll certainly recheck all pulley bearings, bolts, and alignment when I take this belt off.

I was just wondering if anybody had any experience specifically with the belt sliding forward on the crankshaft pulley. I didn’t know if that can be indicative of something outside the pulley system like motor mounts.

also wondering if anybody has had success with alternate aftermarket 98 inch serpentine belts. This one felt very tight going on at 98 3/4. If that’s the case, would it make it more prone to slipping when the motor moves?

I used the Bando 8PK2490, which is 249 cm (2490 mm) equals to 98 inches... It works quite well for my 1999 M1123:

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