Why is my serpentine belt continuously shredding?

[wogmail]

2002 H6 Outback, LL Bean. 140k miles, car is 6 months or so new to me, no mechanical history on it. I have replaced CV axles, changed all fluids, serviced transmission, replaced filters, etc.

Serpentine belt shredded on the interstate, I took it to a chain shop because it was on a weekend. They replaced the idler and the belt. I asked them to replace the tensioner at the same time, they said it was a waste of money.

Three days later, belt is shredding again. They told me they didn't know what was wrong, and put another belt on it and to go to the dealer.

Took it to my regular mechanic, they said it looked fine, that the aftermarket idler seemed a little big, and that the tensioner had play. They said to drive it until it become a problem, but that it looked fine at the moment. Couple days later the belt starts shredding again.

Took it to the dealer, the dealer told me the aftermarket idler was a problem, as well as the tensioner being too loose. I mentioned occasional issues with steering, because I know that the power steering pump is on the belt. They replaced both the (new) idler and the tensioner, and also replaced the power steering pump.

Now, three days later, the serpentine belt is shredding again. What gives?

[rasterman]

Crank pulley separation? I just saw a thread about that...

[wogmail]

Originally Posted by rasterman

Crank pulley separation? I just saw a thread about that...

This is something that three separate mechanics could have missed?

Timeline:
1. Chain store (Merchant's Tire & Auto) looks at car
2. Merchants looks at car again when belt strips again, say they watched the belt for 1.5 hours and could not figure out the problem
3. My regular (trusted) local mechanic looks at it
4. Dealer looks at it

[rasterman]

Whatever it turns out to be, three separate mechanics did miss it. Maybe the pulley, tensioner & idler are all fine. New pump, very nice.

Has anyone checked the other driven accessories on this belt? Alt? AC? WP?

[wogmail]

Originally Posted by rasterman

Whatever it turns out to be, three separate mechanics did miss it. Maybe the pulley, tensioner & idler are all fine. New pump, very nice.

Has anyone checked the other driven accessories on this belt? Alt? AC? WP?

I don't know, I'm just getting hit from every angle here. I don't have any faith in the dealer or the Merchant's. My local mechanic I trust, but he is the only one I haven't given any money too, I just pulled up and he looked under the hood while it was running. I feel like one of the two people I have already given a bunch of money to should be fixing the problem, and since neither the parts or the labor included so far have helped, should probably be giving me some of my money back.

I don't think the power steering pump needed to be replaced, and I don't think the new aftermarket idler needed to be replaced. The dealer takes forever to get parts in, I had a rental for a week ($300), and the dealer's bills was $1200+ for apparently no change. I'm pretty ticked off with Merchant's and the dealer, and pretty ticked off at myself for bringing it to either one of them to begin with. Should have just waited for the weekend to end and taken Monday off.

Any advice for dealing with the local dealer? Any chance I'm getting my money back for anything?

[cardoc]

Is the belt routed proper?

If the belt is routed correctly, one of the pulleys is bad.

[wogmail]

It seems to be routed correctly. Is there some way for them to test which pulley is bad without ordering a new pulley and putting it in? At this point I don't know whether everyone I've been to is incompetent or if this is a difficult problem. I spoke to a mechanic who is a friend and she basically laughed and said it should be simple. Not sure if that's true.

[wogmail]

Just called the dealer. They really seem to not care. They told me to bring it in on Thursday, that they are too busy today, and the mechanic who did the work is off til Thursday. So back to Enterprise.

[phatvw]

Originally Posted by wogmail

It seems to be routed correctly. Is there some way for them to test which pulley is bad without ordering a new pulley and putting it in? At this point I don't know whether everyone I've been to is incompetent or if this is a difficult problem. I spoke to a mechanic who is a friend and she basically laughed and said it should be simple. Not sure if that's true.

Take a magnifying glass or microscope and look at the surfaces of all the pulleys. I bet one looks different. Running your fingers along all the surfaces may help too.

[1 Lucky Texan]

the idler and tensioner bearings go bad a LOT but, I don't know that they would cause the belt to shred without making a lot of noise first.

definitely the crank pulley should be checked.

Seems to me, this would be a mystery if the belt gets shredded but no one can spot anything wobbling. in what manner does the belt fail? rear edge, forward edge, etc.?