Alt. Belt Troubles

[jaymanaa]

Hi, Anyone know any tricks for keeping the alternator belt on the pulleys? It's an 85 6.2 in a 3/4 ton 2 wheel drive Chevy. I've been using Gates green stripe belts. Truck has about 115,000 miles with a new harmonic damper at 110,000. It does not have the rubber damper pulley (just stamped steel). I keep it adjusted but it slings the belt about every 2,000 miles. Thanks for any ideas or suggestions, Jay

[BobND]

Likely, the alternator pulley is worn out, and is "killing" the belt.

Replace the chintzy OEM stamped steel pulley with a machined solid steel unit from an automotive electrical shop.

Also, these earlier diesels came from the factory with a ridiculously low output alternator. Trouble is, when that gets swapped out for a higher-amperage unit (sometimes unintentionally, when the original fails), the larger unit is even tougher on the single belt, that apparently is poorly set up, and doesn't wrap around the alternator pulley as much as it should, for a good "grip".

[jaymanaa]

Thanks Bob, Sounds reasonable, I have a good local auto electric shop. I'll give it a try. Jay

[diesel65]

GM had a service bulletin years ago about short alt belt life, the fix was to install the rubber damped pulley.
I did it myself back in 97.
You would also need to order 4 bolts to hold the pulley to the harmonic balancer.

[Dan Wilson]

I found that using a wider belt fixed the problem. I think the original belt is 3/8 wide and i use 7/16 wide belt. I also do this on the air conditioning pump.
The belts last a long time.
Dan

[bowtieluvr]

JAYMANAA,
I had an issue where mine would squeal shortly after replacing and eventually would burn the belt up in a relatively short time(less than 1000 miles), never actually spit the belt however. After discussing this issue with tradesmen at work who work on machinery they told me to try replacing all belts at the same time. They indicated that if the other belts hits the same pulley as the alt belt(which mine did on the crank and water pump) that they could be fighting each other (sitting deeper or shallower in pulley than one another). I followed this suggestion and have never had a problem since.

[jaymanaa]

Yeah, it's not that the belt wears out but it actually throws it. It started happening when I replaced all the belts as general maintenance. It occurs at idle. The belt really bounces between the crank and alt. pulleys. The gates belt was a little wider than what was on the truck, but seemed to nest well in the pulley. The last time it did it I put the old (narrower) belt back on and it has not thrown it as of yet. I haven't had a chance to pick up a new pulley yet. Thanks for the ideas. Jay

[BobND]

Jay,

Do you know the history of the truck... has then engine ever been swapped?

The V-belt pulleys were been changed over the years, and if the setup is mismatched, the belts work against each other, trying to drive the water pump with 2 different ratios.

I had the on a 1984 Sub, and a while back, someone else posted on here about the mismatched pulleys.

Coul you post a photo of the power steering, water pump, and crank pulleys?

[ZZ]

I had the Alt belt problem on almost all of my GM 5.7 Diesels. The main thing that I found was to use quality belts like Gates. The AutoZone Dayton belts wouldn't last no time.