Serpentine belt alignment?

Long story short: 1997 Grand Prix 3.8 NA, 116,000 miles. Recently, my belt tensioner pulley melted and was replaced. I kept the old belt, since it looked okay. I noticed that the belt would overhang the tensioner pulley by about 1/8 inch (toward the passenger side wheel well), no matter where I put it on the pulley. I did some searching and didn't see any similar posts. The tensioner seemed to move smoothly through its range, and all the other pulleys seemed to be in alignment and moving freely. The gap between the tensioner and block was uniform.

Today, the old belt shredded, so I got a new one. It also overhangs the tensioner pulley by about 1/8 inch.

Did the belt overhang contribute to the shredding, or was it just time for a new belt? Will the overhang cause the new belt to shred? Is there a looming problem with the tensioner itself?

Thanks for any insight you might provide. I have to drive a long way and I'd rather not get stranded.

Also, the NAPA gut asked if I needed a "first" or "second" version of the belt. Apparently the later one is 1/2 inch longer. I saw nothing on here about different versions for the non-supercharged engine.

We have old posts that address the issue of the two different designs on the main serpentine drive belt applicable to both the L36 and L67 versions of the SII 3800 engine if you do more research but obviously that is very tedious. You have the first design belt. The second design came out in 1999.

It sound sounds like you need a tensioner assembly or just a tensioner pulley. On that there are two designs too. You should have the first design tensioner. 1999 and up have the second design since GM redesigned the tensioner assembly.

I have a question, can the 2nd designed belt tensioner be used with the 1st designed belt tensioner.

I have a question, can the 2nd designed belt tensioner be used with the 1st designed belt tensioner.

Not to my knowledge. Also, recall the tensioners mount differently on the engine, The '99 and up use two plastic bypass elbows where the first design uses only one to the lower intake manifold. The other part (bypass) of the first design tensioner is a metal tube with o-ring.

If the tensioner pulley is the only one out of alignment, then I would say that's where your problem is. Since the gap between the tensioner body and arm is uniform, I wonder if it got bent when the pulley seized?

On the belt, the 97, being a first model year does show two different belts possible and it references the OEM belt number. By VIN, it doesn't break it down, so if you don't have the OEM belt, or the one that came off is too shredded to get the numbers off of, it's going to be a trial and error as to which belt your car uses.

OEM belt 24505042 is 2365mm long (93.0")
OEM belt 24506984 is 2372mm long (93.5")

If the tensioner pulley is the only one out of alignment, then I would say that's where your problem is. Since the gap between the tensioner body and arm is uniform, I wonder if it got bent when the pulley seized?

On the belt, the 97, being a first model year does show two different belts possible and it references the OEM belt number. By VIN, it doesn't break it down, so if you don't have the OEM belt, or the one that came off is too shredded to get the numbers off of, it's going to be a trial and error as to which belt your car uses.

OEM belt 24505042 is 2365mm long (93.0")
OEM belt 24506984 is 2372mm long (93.5")


On my Accessory Belt Routing Diagram It has # 245069, I'm assuming this is the 93.5" belt?

I wanted to sign up quick and thank everyone who has replied to this thread. I had an issue with a noisy belt on my 1997 Grand Prix GT for some time and finally got around to doing something about it(way to wait for the coldest days of the year...). I replaced the pulley with no effect on the squeal. I picked up a can of the belt dressing only to have my belt pop off right in the parking lot of the store. While looking at the belt I noticed it had a few chips in it and decided it was probably the belt all along. I wasnt sure which belt to use since it doesnt seem its clear cut which belt length is correct for which motor. I decided to go with the longer(93.5) of the two goodyear belt options since the tensioner could take up the slack but I couldnt make the belt longer. It seems to be the correct one since there is no longer any belt noise. :)