1997 Grand Prix - Serpentine Belt Jumps

Hi,
Anyone have some ideas why my serpentine belt jumps 1 groove on the crank pulley? I have tried 2 new belts and both did it at only a few
thousand miles run-time. It's the 3800 series II VIN K (97 Grand Prix GT).
Car has 73K, at around 40K I had the alternator, water pump, and aircondition compresser replaced. I also replaced the tensioner pulley with a newer model for the last belt hoping for the best--no luck.
From what I've read, I should check pulley alignment and perhaps the harmonic balancer. Since the belt feeds onto the crank pulley from the compressor I'd suspect that pulley first. Are these pulleys really able to be lined up?
Thanks, Chad
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snipped-for-privacy@epix.net says...

Yeah they are able to be lined up or they jump just like they are. Why did you have all of those items replaced??? With all those items replaced its hard to tell whats going on there. Was the crank sensor ever replaced or was the crank pulley ever pulled? There might be some play with the ac compressor. There might even be some loose bolts. Try looking down lining up all the pulleys by sight and seeing if something doesnt look right. All the grooved pulleys must be lined up or your belt will jump.
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says...

Well, unfortunately the airconditioning compressor started a rattle like a bad bearing, the alternator bearing went and it sounded like I had a siren. The water pump let go - all over the garage floor. Sigh. And that's just the beginning of the problems I had with this car :(. The car has always been serviced at my dealer so I'd like to think they did the 'job right' the first time. I stopped by to pick up a belt and they said 'sounds like it needs a new tensioner'. I'm not so sure about that though...
Also, no replacement of the crank sensor or pulley. I'll try to check them by eye, but I think it will end up in the shop for this...
Thanks, Chad
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wrote in message

I'm pretty sure the pump is still there <grin>. I'm just waiting for that to go next. My headlight did fall off though. The belt seems to run smooth over the pump, but I'll be checking it more closely tonight...
Thanks, Chad
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I had exactly the same problem back in the 80's with a very old GM Eurosport. Never seemed to fix it untill one day the main crank just fell off and I had to drive it to the shop with no power steering, alt. or water pump.
The rubber of the harmonic balancer had dry rotted and fell apart.
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snipped-for-privacy@worldnet.att.net says...

They dont use a harmonic balancer on 3800's. Its just a crank pulley now so that wont be an issue here.
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says...

The dealer's comment is "replace tensioner". Pretty Generic answer. I'm aware that this is not a simple task on this engine since the bracket is part of a water channel. Which means it ain't cheap - and it seems like a guess to me.
Anwyay, lining up by eyeball, I'm fairly convinced that the AC pulley is about a groove out compared to the crank pulley. I think it might be a hair crooked too. I noticed that there are 4 bolts holding this thing on, and there is some form of spacer between the frame and the compressor. Are these spacers slightly crushable? Can I give a turn on each bolt to shift the compressor inward? If so do I loosen what appears to be a locking nut and turn the inner bolt 'thingy'? Yeah I know I'm not that mechanically inclined :)
Thanks, Chad
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snipped-for-privacy@epix.net says...

The tensioner is the easiest thing to replace on that engine. There is one bolt and it does not go into a water jacket.

There are 2 bolts holding on the front bracket and 3 more holding the front of the compressor (5 in front). In the back there is a L like bracket with 1 bolt going into the block and 2 going into the compressor (3 in back). That might be the area u need to check. You can see it from below at the back of the compressor. If that one isnt attatched I could see your compressor being pulled in by the belt. My guess is someone had extra parts after they finished replacing all that stuff on the front of your motor or missed tightening some spots.
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I blew a tentioner also on a 94 Grand Prix on the way back from a fishing trip. Parked it on side of the road and went to an Advanced Auto Store. THAY HAD IT! 50 bucks!.
Like bonneville said, replaces with one bolt and a 1/2 inch wrench to tention it up to get the belt back on. Done in 15 minutes.
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snipped-for-privacy@worldnet.att.net (Craig Watts) wrote in message

------------------------------------------------------------------------- Here's a paste from another thread (which bonneville was part of).

needs "a

$380.
the
cost
price
And from what I can see this appears to be true. I've already replaced the tensioner pulley which is a 15 minute job, and I've replaced the 0-rings before which is also a 15 minute job. In any case I tried for three hours to tell if the AC pulley was lined up. I can't be sure because it seems to change depending on where I look at it. I don't know if the shop has a belt-hog or other laser alignment tool. I don't notice any strange wear on the belt even after a year. I also couldn't see any missing bolts, but it looks to me like they are spaced as such there are 4 bolts? I can't see 5 if they are there.
Sadly to say (at least for my wallet) is that I have an appointment tomorrow to get the tensioner changed and the pulley alignment checked. At 75K miles a new tensioner is probably a wise investment on these engines. I hear they go all the time...
Thanks for the help, Chad
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I cant remember off hand but that one might of had the 3.4L and not the 3800 that yours has. I referanced a 98 3800 GP when I looked that up in my GM SI program. There is a big differance in these 2 engines.

Like I said 5 bolts in the front 3 in the rear. 3 bolts hold the compressor to the bracket in the front. 2 bolts hold the compressor to the bracket in the rear. 2 bolts hold the front bracket to the block. 1 bolt holds the rear bracket to the block.
CHECK the 3 bolts in the REAR of the compressor.
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--
There was a 3.4L mentioned in that other thread, and there was some
confusion regarding which engines were in the 97 GP. I think the 3.4
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