alternator belt breaks once a week

[colbystephens]

ok, so my buddy's 6.2 is breaking alternator belts like there's no tomorrow. i think he's gone through about 6-8 in the last month and a half. the pulleys look like they're lined up well, but something is clearly not right. the belt pulls pretty straight across the top of the alternator and water pump, as well as up the crank and over the water pump, but as it goes around the alternator and back down to the crank, it wobbles and shakes like the belt is crazy loose. i know it's tight tho - i've tightened it myself a few times. he bought a brand new belt today and broke it on the 2 mile trip home. the only thing i can figure is that perhaps the thrust bearing is allowing too much play - crank moving back and forth in the engine, or the crank pulley is damaged in someway (it's off of a different 6.2 and his alternator is new, so that shouldn't be bad). any thoughts?

 

[88-383]

Get a straight edge out and checking things out. I just went through this with my truck. It turned out, that my PS pulley wasn't seated all the way.
Good Luck!

KM

 

[y5mgisi]

deffintly not a thrust bering in the motor, if that was worn out the crank could still only move mabey a 1/16th. but man i couldnt tell ya exactly what the deal is. Does it squeel real bad or anything?

 

[colbystephens]

it rarely ever squeals

 

[prossett]

Have you run your finger around the pulley to see if there's any sharp bits by any chance?

 

[Indyblazer]

Broken V Belts

My GM Diesel was breaking alternator belts once a month. It started after I bought an Autozone replacement alternator. I thought the alternator was defective so I took it back to Autozone and made them give me a replacement even though it tested OK on the alteranor tester.

One month later with another rebuilt Autozone alternator.... SAME PROBLEM broken V Belts.

A friend that owns his own repair shop and used to be a Semi truck diesel mechanic told me to go to GM for an alternator. He explained that many truck diesel parts are engineered specifically for the diesel application.

I went to a local parts store that had the correct rebuilt GM diesel truck alternators. (New GM parts cost a fortune) When I saw the alternator that GM put on my truck as ORIGINAL EQUIPMENT (Heavy Duty) I was amazed at the difference between the alternator that Autozone sold to me and the CORRECT PART FOR A DIESEL TRUCK.

Autozone had sold me a PASSENGER CAR ALTERNATOR with the same amperage output as my truck required.

I installed the rebuilt GM ORIGINAL EQUIPMENT ALTERNATOR and PROBLEM SOLVED !!

 

[colbystephens]

that's a very interesting story! i'll have to send my buddy this link so he can check that out.