Had the old belt on the car from 2006 until 3 weeks ago. Never had any problems until then. It would squeal a little when I would start the car, but that was it, and then I noticed that there was a groove in the under side of the belt that matched perfectly with the tensioner. After three weeks my new belt has the same squeal on start up, and the same groove worn into it. I'm posting a picture of a factory tensioner so you can see the type of groove it's wearing into the belt.
My question is what would cause this? I'll try to post a picture of the belt after work tomorrow. I know the belt size is correct because it worked fine for 7 years.

 

well, clearly the tensioner pulley needs to be replaced. Its anyones guess how the pulley got like that, but most likely it was/is a misalignment in the pulley system on your ride. The fact that it squealed at all is an indication of a problem. You should get the squeal fixed otherwise you’ll be replacing belts a lot. Good luck...

 

You need to check the alignment of all pulleys using a straight edge , if one pulley is even a half a rib off the belt will ride up on it.


I had a power steering pump once and the pulley was worn out in the center it would ride out on the shaft and cause the belt to squeal. I could press it back with the installer tool and it would ride back out as soon as I started the engine. I checked the inside diameter of the pulley with calipers and it was completely out of round. You could see on the pump shaft the uneven wear in the places where the pully didn't make contact with the shaft.

Another thing that can cause the belt to ride off or squeal is if the belt was left on the car to long , when it starts slipping and squealing it burns the ribs of the belt up and that burnt rubber is deposited in the valleys the pulleys. This causes any new belt to squeal or walk off the pully.

You need to use a wire wheel and on a drill or a bench grinder and clean the old burnt rubber out of the pulleys.

 

Think I found the problem. There is a buildup of rubber where the belt meets the tensioner. I'm thinking that the tensioner has siezed up. Will check my theory tomorrow.

 

Good call dawson1112 on the rubber in the pulley grooves. But a wire wheel might be a little too aggressive in removing the rubber. A wire brush might be better, or just replace the pulley all together. They are less then $10 anyways. Good luck...

 

Tensioner pulley was completely seized. Ordering a new one tomorrow along with some underdrive pulleys