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Belt slips off pulleys
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Author:  detroitmike [ Tue May 05, 2020 2:57 pm ]
Post subject:  Belt slips off pulleys

Hello Everyone

I recently swapped out a new dive belt.
When reattaching the new belt I noticed the pulley on the alternator was tilted towards the motor a bit too much

I got the belt on cinched the lower bolt down then the upper bolt in the bracket.

she ran fine at first but I noticed the pulley on the alternator was twisting the belt

well it popped off after a long run today and a few times afterward.

I removed the alternator and re-seated it in the lower bracket.

I see no way to shim the alternator to straighten out pulley in line with main pulley

there is some run out on alternator on the pulley should I buy a new one?

Any advice would be great thanks

Author:  DusterIdiot [ Tue May 05, 2020 4:37 pm ]
Post subject:  Re: Belt slips off pulleys

I guess a few questions are in order...

Is this a single groove pulley or double groove pulley alternator?

Without the belt on and everything mounted do the pulley grooves line up reasonably with each other?

Gave you checked the upper alternator bracket to make sure that it is bolted tight to the head, and...
have you checked it for cracks?

If it all lines up, and the bracket is solid...are you using a lever to roll the alternator toward the fender
to take up the slack in the belt before tightening the upper alternator bolt to the bracket?

Author:  detroitmike [ Wed May 06, 2020 8:14 am ]
Post subject:  Re: Belt slips off pulleys

Hello Thanks for the reply

Yes a duel pulley alternator some run out

No it is cocked inward towards engine removed and tried to straighten seems a bit better

Yes using lever to extend

Thanks

Author:  detroitmike [ Wed May 06, 2020 8:14 am ]
Post subject:  Re: Belt slips off pulleys

Upper Bracket is bolted to head securely

Author:  SpaceFrank [ Thu Jun 04, 2020 8:34 am ]
Post subject:  Re: Belt slips off pulleys

I've noticed the through-hole on the lower bracket (where the long bolt attaches the alternator to it) can get wallowed out with time. This allows the alternator to shift under belt tension and change the angle of the pulley. Doesn't matter how tight you crank down on the lower bolt. We "fixed" this on the Race Dart by drilling the bracket out one size larger and using a bigger bolt.

The holes in the alternator "ears" can also be wallowed out, especially if it's an old or remanufactured unit. One of the ears has a steel bushing; if that bushing is missing then the misalignment will be very bad. I've ordered an appropriately sized replacement bushing from McMaster to fix this before. Just tap it in gently with a small hammer, and a block of wood supporting the ear on the aluminum alternator body.

Author:  detroitmike [ Thu Jun 04, 2020 2:44 pm ]
Post subject:  Re: Belt slips off pulleys

Thanks for the help

Yes the bolt is a bit wallowed as the pulley is not parallel with the engine once tightened up.

Also the alternator had a lot of run out on the pulley

I ended up buying a reman unit for 28 dollars ans the pulley was good.

Re installed and have not thrown a belt yet

thanks

Author:  SpaceFrank [ Fri Jun 05, 2020 9:18 am ]
Post subject:  Re: Belt slips off pulleys

Oh, I missed what you said about the pulley runout. A new alternator sounds like a good place to start. Good luck!

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