What are the symptoms of a broken balance shaft belt?

SpicyOrange · 03-03-2005

My 95 GS-t has developed a high Rpm vibration that shakes the entire car upon acceleration. I also notice that it vibrates violently when I downshift into 3rd gear on the freeway and the rpms rise. Is it possible that BS belt has snapped and would cause this?

Thanks

Nick

**Goat Blower** · 03-03-2005

Sure sounds like it.

Raptor · 03-04-2005

Sounds like it and I wouldn't drive it till I knew for sure. Don't want to lose the timing belt as well.

john · 03-04-2005

I had a broken b-shaft belt after a bad install but it didn't seem to run any different. I didn't loose the t-belt. Luckly I swapped the t-belt at 20K as another bad install (wrong bolts in the oil pan) wore a a groove in the timing belt. I would pull off the timing cover for sure though. Defintly cannot hurt anything. Vibration could also be caused by a bad motor mount.

Raptor · 03-04-2005

If the bearing on the rear balance shaft went, it could make some pretty nasty vibrations as well, should hear that pretty well if it were the case though.

SpicyOrange · 03-04-2005

Thanks guys. I'm gonna tear it apart tonight after work.... I forgot to mention that I just got it running and was breaking the clutch in and the Timing belt was next on my list of shit to do since the previous owner never replaced it and the car has 109k on it. So I sure hope that is my vibration, other wise I am stumped.

SpicyOrange · 03-05-2005

Quote:

Originally Posted by Raptor

If the bearing on the rear balance shaft went, it could make some pretty nasty vibrations as well, should hear that pretty well if it were the case though.

So tell me more about this bearing? Is it common for it to go out? Is there any diagnosis to see if it is bad?

I did the Timing belt and balance shaft belt tonight and once I had it apart I knew it wasn't gonna fix anything. The motor has a pretty bad shake at idle, and you can feel it get noticably worse at 3500 rpms. I almost positive its in the motor. Pushing the clutch in has not affect on the vibration. It will vibrate while the car is standing still or moving at 60mph. Please help!

Nick

john · 03-05-2005

2600 clutch?

SpicyOrange · 03-05-2005

Spec stage 1

Raptor · 03-05-2005

Check the oil for bearing material. The balance shaft that is driven off the oil pump has a bearing that fails on the end opposite the pump fairly often. I have seen several this year, that can cause it to shake, but there is also usually a noise associated with it as well. As far as checking it, pulling the pan is the best way to know for sure that it is bad or not. Half the time it fails you will find a mangled bearing in the pan.

The one thing that hasn't been brought up in this thread and should is that the obvious things are often overlooked. Don't make the mistake of pinning this on something severe until you know the car has no other more simple issues that can cause this as well. Make sure it is firing on all the cylinders etc. A bad plug wire or plug can cause the exact same vibrations you are talking about. Listening to the engine would obviously help us to trouble shoot the problem and on that note, if you are anywhere near the shop, maybe I can come over quick and give you a better idea whats up. If thats the case, give me a call.

SpicyOrange · 03-05-2005

I was gonna try to get a fuel pressure gauge on it today. and possibly throw a new fuel filter and plug wires on it. I just might have to hit you up on checking it out, all my mechanic friends are kinda stumped at the moment but we wanna check some of the basic things first.

SpicyOrange · 03-05-2005

The thing that baffles me is that it its not load related. It will shake just revving it up sitting in the driveway, it always shakes above 3500, on Decel, accel, or coasting. Clutch in, clutch out. I really thought it was the BS belt.

Raptor · 03-05-2005

It still sounds like a balance shaft issue or similar, but as always, make sure it isn't something simple before checking the things that take more time and money. If you need me to hear it, let me know. I won't charge you anything to come out and listen if you aren't too far from the shop.

SpicyOrange · 03-05-2005

Maybe I'll cruise up to the shop, are you there today? and where abouts are you guys located?