serpentine belt shredding

[ericn1300]

92 Bravada 4.3 vin W 207,000 miles. My wife's vehicle. The serpentine belt shredded off the segment on the engine side which wrapped around the fan shaft and made enough noise for the dumb blonde to have me take a look at it.

I replaced the belt and checked for anything rubbing against it, found nothing. The new belt lasted less than a half tank in the gas guzzler, about 200 miles. I took off the shroud this time and gave it a good look over and can't see any problems.

Both times it seems to have happened at start up. Here's a pic of the new belt:
http://www.geocities.com/ericn1300/Belt1.jpg
http://www.geocities.com/ericn1300/belt2.jpg

[MT-2500]

Sounds like my luck when working on my own stuff.

Check belt tensioner for proper tension.
Spin and check all idlers and pulleys.
And tensioner for alignment.
Sometimes the plastic pulleys wear out.
Air cond bearing and ps and water pump for being lose or feeling rough when turning.
Crank shaft damper for lose or out of alignment or wobble.
When you install new belt watch for and flopping or out of line pulleys.
Also make sure pulley groves are clean.
After you put another new belt on eyeball all pulleys from side and make sure one is not out of line.
Or crankshaft damper coming out or off.
Good luck
MT

[ericn1300]

Thanks for the quick response MT. All the pulleys and accessories seemed to turn fine with no wobble or play and alignment was good. No bouncing in the belt. No hoses or clamps hitting the belt. I used Chris's method to check for broken motor mounts, no problem there so I decided to change out the tensioner assembly and idler pulley.

MT, you were right about the plastic pulley wearing out. The old one was grooved, had flat spots and was crowned in a way that biased the belt towards one side. The replacement part is steel and will probably out last the vehicle. Pic here: http://geocities.com/ericn1300/IdlerPulley.jpg

Can you tell me what the arrows and corresponding marks on the tensioner assembly mean?
http://geocities.com/ericn1300/oldtensioners.jpg
http://geocities.com/ericn1300/newtensioner.jpg

This problem came at the worst of times since my idiot niece decide to have a “destination wedding” this weekend which will entail a 700 mile round trip to a ski resort and I really want to take the 4x4.

[Chris Stewart]

The marks are for acceptable belt wear range. The pointer should be pointing to one of the raised hash marks when the belt is new.
The acceptable range as the belt wears is a lower hash mark to the right.
The extra marks are for non-AC applications.
Is the new belt ok now since you replaced the parts?

What's a destination wedding? Does it involve a dowery? Did I ever tell ya about my neighbors goat?
Do you hafta show up or can you just send a representitive and a gift card?

[MT-2500]

Ericn1300
You are welcome and thanks for letting us know how it is going.
Yes the old worn pulley could have done it.
If the tensioner belt marks are close and the tension is keeping the belt tight and has extra adjustment it should be ok.
But a spare belt and tensioner wrench in the trunk would make a good backup for a long trip.
The new pulley or brand of belt can change the mark line up a little.

Good Luck