As some of you may recall, I put a GM Performance crate 454 in my Allegro (I bought the rig with a blown engine). I swapped over the brackets and pulleys from the blown engine to the "new" engine. The only exception is the smog pump. The crate engine didn't have one, and had the appropriate sized belt to account for the lack of a smog pump.Since the engine was used, and the belts too, I cross-referenced the old NAPA belt to a Gates 7470 (the NAPA belt said 7470 on it, too) and put a new belt on it. Well after about 30 miles of driving the new belt is trashed. The edges are chewed up and it's missing a lot of teeth.It appears as if everything is lined up properly and the pulleys look good. Can overtightening the belt cause this? It kept loosening up and slipping so I made it pretty tight using a crowbar. I've ordered 2 more belts to experiment with but they're pretty hard to come by.

I had the same problem on an 82 Chev 6.2 diesel. It would destroy the alt belt within 4~6K miles so I had to replace it every time I changed the oil.I replaced the alt. and all the pulley's and everything lined up perfectly but it still did it and I never did figure out a fix.The only thing I could think of is that since it didn't have AC, the belt had a long, straight shot between the pulleys. In this space the belt would whip inward and outward in a blur of motion continuously. Did it no matter how I tightened it. I think this fatigued the belt to failure. I thought about trying to create an idler to control the motion but never got around to it.Sorry that's not much luck but maybe it will give you some idea's.Hope you have better luck.Scott

Triple check that alignmentTry a straight edge across the face of each and every pulley, facing it to another pulleyAnd yes, you can over tighten, it's normal for a new belt to stretch a tad, but not loosen, The specs call for a specific amount of deflection= give, in the middle of the belt, that is how you set belt tension, check the manual for the amount adjust belt tension so that belt deflects= gives the correct amount

Take a picture of the belts, looking down on them. You can post the picture to Photobucket.com When you set up your account, make everything viewable to the public without signing in. It will really help us in trying to figure this out. My guess is that one belt is not lined up correctly. It might be offset by 1/2" or more from the centerline of each pulley. Fred.

Well, here are some pics. If not for the request for pics, I would not have realized that the power steering belt is on the wrong groove in the crank pulley! I'm such a dope! In my defense, however, you can't see down there unless you stick the camera in there an snap a pic like I did. But the PS belt hasn't been giving me any trouble (the one with the grooves). It's the other belt that has shredded.

Had a similar problem on the same unit purchased used. Finally an old back yard mechanic told me that they had installed a rebuilt alternator from Mexico and that the rebuilt unit had a metric pulley instead of an American. Anyway he went to a junk yard and brought one back that he said was the right one. How true that was I do not know but it took care of my belt problem...Good luck

1984 P30 454 Shredding Alternator Belt | Good Sam Community

Golden_HVAC
Explorer
Jun 17, 2014
Take a picture of the belts, looking down on them.

You can post the picture to Photobucket.com When you set up your account, make everything viewable to the public without signing in.

It will really help us in trying to figure this out.

My guess is that one belt is not lined up correctly. It might be offset by 1/2" or more from the centerline of each pulley.

Fred.
MrWizard
Moderator
Jun 17, 2014
Triple check that alignment
Try a straight edge across the face of each and every pulley, facing it to another pulley
And yes, you can over tighten, it's normal for a new belt to stretch a tad, but not loosen,
The specs call for a specific amount of deflection= give, in the middle of the belt, that is how you set belt tension, check the manual for the amount adjust belt tension so that belt deflects= gives the correct amount
ScottG
Nomad
Jun 17, 2014
I had the same problem on an 82 Chev 6.2 diesel. It would destroy the alt belt within 4~6K miles so I had to replace it every time I changed the oil.
I replaced the alt. and all the pulley's and everything lined up perfectly but it still did it and I never did figure out a fix.
The only thing I could think of is that since it didn't have AC, the belt had a long, straight shot between the pulleys. In this space the belt would whip inward and outward in a blur of motion continuously. Did it no matter how I tightened it. I think this fatigued the belt to failure. I thought about trying to create an idler to control the motion but never got around to it.

Sorry that's not much luck but maybe it will give you some idea's.
Hope you have better luck.

Scott

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1984 P30 454 Shredding Alternator Belt

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