M1097 - Serpentine Belt Issue

[4x4nutz]

Got the mil spec serpentine belt I needed for my M1097, but the darn thing won't stay on. It comes right off as soon as I start the humvee. I did find that a 8 inch bolt on a guide pulley was bent, and after I replaced it, the belt stayed on for about 45 seconds and came off again. I have spun all the other pulleys and none of them wobble, seem bent, or have a spacing issue. What should my next step be?

 

[Action]

Post a pic or two of your motor. That may help to identify an issue. That pic you posted looks too familiar to be yours....

 

[4x4nutz]

Post a pic or two of your motor. That may help to identify an issue. That pic you posted looks too familiar to be yours....

 

[doghead]

Did the old belt stay on?

 

[4x4nutz]

Did the old belt stay on?

There was no belt when I bought it.

 

[Rmtaunton]

Put belt back on have someone crank it and see which pulley is bent or out of Aline should be easy to spot


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[4x4nutz]

Put belt back on have someone crank it and see which pulley is bent or out of Aline should be easy to spot


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We tried just bumping it to see where it would start coming off and it wouldn't come off. When we actually started the engine and ran it, it comes off so fast you can't see what pulley it starts coming off of first.

 

[Action]

I have seen plans in a TM to build a pulley slignment check tool. Is the tensioner springy enough?

Turn the motor by hand with belt on until it starts to come off. I installed pne with one groove hanging off the pulley lip. It just ripped off that groove.

 

[4x4nutz]

The tensioner seems to be fine and has to be pushed all the way back to barely get the belt on. Can't really turn the motor by hand....but we tried bumping it by just hitting the starter over and over, but the belt would not come off. Only came off after it was running for about 30 seconds...

 

[Wire Fox]

You should be able to put a socket on the crankshaft just below the fan, at the front of the engine. I could turn it by hand with a standard 1/2" ratchet. That should give you smoother rotation and will give your assistant a better idea as they carefully watch each pulley for what is bent or out of alignment. It's way too hard to try and spot a wobble from something that's turning fast in short bursts.

 

[4x4nutz]

You should be able to put a socket on the crankshaft just below the fan, at the front of the engine. I could turn it by hand with a standard 1/2" ratchet. That should give you smoother rotation and will give your assistant a better idea as they carefully watch each pulley for what is bent or out of alignment. It's way too hard to try and spot a wobble from something that's turning fast in short bursts.

Thank you....will try tomorrow.

 

[dilvoy]

Got the mil spec serpentine belt I needed for my M1097, but the darn thing won't stay on. It comes right off as soon as I start the humvee. I did find that a 8 inch bolt on a guide pulley was bent, and after I replaced it, the belt stayed on for about 45 seconds and came off again. I have spun all the other pulleys and none of them wobble, seem bent, or have a spacing issue. What should my next step be?View attachment 697029

I always love seeing photos of my engine being used as reference photos. I had to piece that **** thing together piece by piece back then.
You might pay attention to the flywheel damper and pulley area. That setup is a weird one. it is designed to allow the pulley to rock in relation to the crankshaft. Maybe something has let go or cracked or is just plain missing a couple of bolts. There is a spacer in the mix too.

 

[Action]

Dilvoy. I thought that was your pic from many years ago...

 

[4x4nutz]

It's the pic someone sent me a few weeks ago for a full frontal view without everything in the way....not like it's copy righted....lol....will check the flywheel damper and tensioner for any issues today. Just waiting for a friend to help out.

 

[Action]

What length belt are you using? There are several different ones used on these.

 

[4x4nutz]

It's a Masterpro 8K981.....so I am thinking it is 98.5 inches.

 

[Action]

It's a Masterpro 8K981.....so I am thinking it is 98.5 inches.

That belt is 1 3/32" x 98 5/8".
It looks like the belt for serial number 196,901 and below is 12469149-1, which is 98".
Dayco 20-8021

A belt that is too long could jump easily....
I would spend the $25 - $30 and try that one...

 

[4x4nutz]

I had that tensioners back as far as it would go and we could barely get this belt on....+ it's the exact same belt we found hanging from the crank shaft when this humvee was delivered.. You still may be right, and we just have to winch that **** thing on there....lol

 

[Action]

I have a turbo, but when i put the belt on, I remove the top bolt for the alternator then tilt it in. I use the ratchet in tensioner and get the belt on. Still while holding the tensioner, i pull thd slternator back out and put the top nolt back in. I have lips on my pulleys, so just moving thd tensioner will not let me get the belt on.

 

[Wire Fox]

I have a turbo, but when i put the belt on, I remove the top bolt for the alternator then tilt it in. I use the ratchet in tensioner and get the belt on. Still while holding the tensioner, i pull thd slternator back out and put the top nolt back in. I have lips on my pulleys, so just moving thd tensioner will not let me get the belt on.

Removing that bolt for additional tilt is a pretty smart-sounding idea. I had some struggle with new V-belts on my HMMWV and I ultimately just used a technique that was similar to a bicycle shifting gears...starting with the inner-most band, I'd loop it around everything and get it set onto the first groove. I'd then use one hand to displace the belt and direct it toward the next groove while using the free hand to spin the belt and cause it to push itself to the next groove. While this worked without taking out any bolts, it was time-consuming and rather annoying. Taking that bolt out as you've describe should help for either V-belts or serpentine belts and really speed up the job.