I've been trying to find the source of the belt noise on my 4.3L 1996 Jimmy for over a year.

1. All the pulleys are fine. I know this because if I change the belt, the noise goes away for a few weeks, but then gradually comes back.

2. Good quality belts (Dayco)

3. Replaced belt tensioner, alternator, and idler pulley.

4. A/C Compressor unplugged

5. All the pulleys are aligned with a straight-edge.

It seems like something is contaminating the belt, but I cant figure out what. The backside of the belt feels tacky. Cant find any oil/antifreeze leaks)

Are there any known issues that could be causing this? Its driving me nuts.

 

You said
It seems like something is contaminating the belt, but I cant figure out what. The backside of the belt feels tacky

Ok it sounds like one of your pulleys are starting to seize up when it gets warmed up

look at what is being moved bye the back of the belt ac alt. ps
what ever is riding on the back of the belt sounds like it is your problem if the pulley stops or even moves slower then the belt then it will heat up your belt and make it tacky and hot its burning up is what is happening

when it starts stop dont shut it off pop the hood and give it some gas see if you can see smoke from a pulley or see 1 stopped

 

Only the water pump and the idler ride the back. Both are easy to determine.. not them, i had same thing

Did you actually replace the tensioner.. or just the tensioner pulley?

ummm ...no it's not good quality..

I gave up and put on a gatorback about three weeks ago and now it's fine. I prolly should have got a new tensioner but I like minimal tension on belts. I use Dayco on my Tbird 3.8 and never a peep but has a lot more tension.

 

I replaced the entire tensioner assembly (with pulley). Also replaced the idler pulley.

 

then just give up and get a gatorback. They are hard to find in a store, bought mine from Rockauto but Goodyear tire store should have them.

 

Thanks, I might give it a try.

It just seems funny because the belt life was just fine for 14 years, and now I can seem to keep a belt on it for more than 2 months.

 

I've been addressing this same issue on a 2000 and a 2001. If I spray carb cleaner on the belt while running the noise goes away for a very little bit then comes back. I've taken a flathead screwdriver and placed it on the idler pulley while running with firm force and scraped off the paint and the noise quieted down. There is a clicking sound on initial start up and I suspect the power steering pump is causing this noise. After driving around for 10 minutes there is no noise at all but for a click every now and then. I am suspect of the movement in the power steering pulley but I've noted it on three different Blazers. The pulley can be pushed in and out a little. My belts have the same tacky film on the back side. I've sprayed the belt with belt dressing and this does no good either.

 

are you sure your oil cooler lines are not seeping and spraying up on the pulleys? when you have the belts off are you spining each pulley by hand, feeling for roughness in the bearings?

 

If the belt is dirty take some comet (a white powder usually in a green can) and dump some on the pulleys and belt while the truck is off then start her up and no more squeaks.

 

And why not?

Hey frog im not trying to say your wrong, but you may be
I have seen and had water pumps work fine when there cold and at idle but hold back and cant move at the rpm"s that are being demanded. and the belt don't jump or anything

I have also come across a problem with my moms 02 blazer when the clutch fan broke and was locked up and on full all the time. That happen to bake the back side of her belt and make it sticky

My Moms clutch was electronic I'm am not sure if his is or not
I passed over the belt tensioner and pulley because he said he replaced it.
I have never had a problem with dayco I have had more problems with Good year

and also I have seen people put belts on wrong. How they do it I don't know but I have seen it and had to cut the belts because I couldn't get them off to tight

I am just saying it could be the problem with out me seeing it with my own eyes and ears I cant say it is or not and you cant for the same reason

it may or not be any reason that any one of us are posting
he is only asking for ideas and
I would go over everything starting with a Belt Tension