Belt shredding after new alternator

IllCobra

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Installed a Mechman 170 alternator and after doing a pull from 2000 to 4500 for my tuner, the car ate through the side of my new gates belt.
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It looks like the belt is walking toward the front of the pulleys and getting chewed up. All was good before I installed this new alternator, so it must mean I need to modify it to correct this? When I first started the car after the install, the car made a loud noise so I quickly shut it off and looked to see what it was. I didn't see anything so I started it again, it made the same noise for a second and then stopped and all was normal. Drove it around for a few miles, did some mid accelerations, and all was good. It wasn't until I did the pull for my tuner did it eat the belt.

I searched to see if there was any threads about this, but all I found are threads about alternators failing. Anyone have any ideas on what I should do, or provide a link to a thread that can help? I'm assuming I'll need washers and maybe some tool to ensure the alternator is lined up correctly?
 

me32

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At idle what does the belt look to be doing? Have someone in the car rev the car up slowly and pay close attention to the pulleys and the belt.
 

IllCobra

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At idle what does the belt look to be doing? Have someone in the car rev the car up slowly and pay close attention to the pulleys and the belt.
All looked fine at idle. Only rev'd it to about 1500 rpm and all was good, didn't rev any higher as it looked good at idle and slight rev. Too late to give it another test though since the belt is unusable now. Ordered another belt which wont be here until next week or so.

What should I have been looking for?
 

NateDogg

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I had issue with this when I had a lower on the car. The idler pulley to the right of the lower needs to be shimmed a smidge. I can't remember what size washer I used but it was minimal.

Not sure if its the same issue you're having since it just started after the alternator was installed.

Maybe the Alt pulley is mis aligned.
 

IllCobra

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I had issue with this when I had a lower on the car. The idler pulley to the right of the lower needs to be shimmed a smidge. I can't remember what size washer I used but it was minimal.

Not sure if its the same issue you're having since it just started after the alternator was installed.

Maybe the Alt pulley is mis aligned.
How did you tell which pulley was the one causing the issue? I didn't change any of the idlers, I feel my issue is going to be something with the alternator.
 

NateDogg

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It was a common problem that people had posted about on these boards. I shredded a few belts and couldn't figure it out.

You can rent laser pulley alignment tools that can help you check to make sure everything is lined up. I think O'reilly's has them.. If not they are relatively cheap to buy.. 75-100 if I remember correctly.
 

IllCobra

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I had the same problem with my Mechman 170a. It turned out there was a small spacer under the pulley. I took it out and it has been perfect since.
I am going to try that and hopefully that fixes it.
Is the alternator pulley suppose to line up evenly to the crank pulley? Like if I put a leveler to the crank and alternator pulley, the alt pulley shouldn't be further in or out then the crank pulley?
 

Dave.O

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I had issue with this when I had a lower on the car. The idler pulley to the right of the lower needs to be shimmed a smidge. I can't remember what size washer I used but it was minimal.

Not sure if its the same issue you're having since it just started after the alternator was installed.

Maybe the Alt pulley is mis aligned.

This straight edge alt pulley against two adjacent pulleys
Depth might be off


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IllCobra

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It was a common problem that people had posted about on these boards. I shredded a few belts and couldn't figure it out.

You can rent laser pulley alignment tools that can help you check to make sure everything is lined up. I think O'reilly's has them.. If not they are relatively cheap to buy.. 75-100 if I remember correctly.
I am going to call my parts store and see what they got.
 

Four Door SVT

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We had one that was .25” larger at the mounting flats than the one we took off


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cj428mach

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The lower bracket has that metal spacer that moves in to clamp the alternator. You can move that spacer out towards the front of the car and drop washers either in front or behind the alternator to get it spaced in the direction you need. I'd say that by looking at the belt movement you need the alternator to go towards the rear, to me the easiest way would be to put an washer or two on the front side.
 

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