RED99

I am going crazy with this belt drive. It was making a terrible oscilating squeal. I fixed that wirh a new belt. The one I took off was only about 4 weeks old, and had 2000 miles on it from a trip.
I just replaced all the bearings, and tensioner, belt, and alternator. If I take the belt off, it runs quiet. You can see in the video, something is causing tension on the belt and releasing. This is probably making the clanking noise. But WTF is it?
Could the PS or water pump be picking up air? That's the only thing left, besides the blower. But I have taken the rear belt off once, and it still made the noise. So it's got to be either the water pump, or PS pump. I need help before I go crazy.

ajg1915

It sounds like something hitting.

I would take off the belt and spin each pulley and see if something is rubbing. or loose.

MIKE-C5

Sounds to me something is hitting! ! If it was a bearing it would be consistant! ! I bet the belt is hitting something! ! Do you have the right size belt! ! Make sure there is enough tension! !

RED99

I've done that about a dozen times now.

RED99

Yes, right size belt, and it has plenty of tension.

RJW

The knocking sounds like it could be the tensioner bottoming out. Is it?

You could bottom it out by hand and put some witnes marks on the mating parts and then run the engine and see if the marks line up...then a longer belt or move some stuff around so that it doesn't bottom out.

The big question is why...outside of the belt maybe being too short, that amount of tensioner deflection is usually either

1) something not turning true....which doesn't seem to be the case

or

2) a binding in PS pump or other accesory.

You had the car at Andy's and he couldn't find the problem?

Have you put a stethoscope to each of the accessories..alt, ps, w-pump, and all the idlers including tensioner to try to isolate the cause?

What happens when you rev the engine?

RED99

Yesterday I replaced the tensioner pulley bearing and the tensioner itself because I was getting a bad squeal. That didn't do much. So I went and got a new belt, and put it on. That stopped the squeal. I heard maybe one or two faint clanks when I first started it, then it quit. I drove the car for 20 or 30 mintues, and it was very quiet. I get up this morning to take it to work, and it started the clanking noise again. I let it run for at least 5 minutes while shooting the video this morning, and it never would stop.
If you look at the video, you can see the tensioner pulling down, and raising up as it's making the noise. Something is making a load, and releasing. It's got to be either the water pump, or the power steering pump. Everything else has been replaced.

RED99

It didn't do "That" at Andy's. But I was getting a belt squeal. So he added a spacer on the alternator to give it more tension. He thought maybe the tensioner was bad because he pulled on the belt, and it seemed like it could stand to be a little tighter. So I got another tensioner. But the problem is still there. That's the other wierd thing. One day it does it, and another day it doesn't.
Also, it seems that when it's clanking, the belt doesn't squeal. When the belt squeals, it isn't clanking.

RJW

stethascope?

Skunkworks

Something is likely only binding up under load (tension from belt and drag of blower).

Does it get worse at higher RPM (higher tension load)?

Turning stuff by hand is not the same as having a few hundred pounds of load from belt on it.

Mike

EDIT---I've seen stuff that appeared good under no load, but once loaded problems manifested themselves.

RED99

I jsut started it up, it took about 10 second before it started to make some noise, then it clanked for a few seconds, then it quit. Now it's quiet. I wish what ever it is would blow up so I can replace it.

Skunkworks

I really don't think this the problem, but maybe look at tensioner as there is usually a plastic piece the adds resistance and dampens response to keep it stable. This may be a problem later down the road because of violent motion.

To be it still seams like a bearing/gear... but just a guess.

Mike

RJW

Keep going around the block at 7k... Hard on and off the go pedal and see what happens?


I agree...enough is enough...time to blow it up, whatever it is...

RJW

when it's quiet, is the tensioner still moving that much? probably not?

RED99

No, the tensioner is steady when its quiet.

RED99

I just got back from driving the pi$$ out of it. The clank seems to have gone, for now anyway. I think she just wanted me to drive her hard.

RJW

The 'Red' school of self healing corvettes...

Keep us posted...if it's serious, it'll take a dump sooner or later...no?

RED99

My old school solution to weird noises was to go buy some bigger speakers.

RED99

Now the belt squeal is back, and it's really bad. Just put the belt on yesterday. It's quit under 1500 rpm, and gets louder as the rpm goes up. I saw some belt dust on one side of the inside alternator pulley(weird).
Then coming into the parking lot here in the condos, the rear end starts making this clanking noise. I parked the car for a minute, and then took it around the parking lot and it was gone. The car is posessed.
I have it going in a show n shine cruise in tomorrow, Autocross on Sunday, and Tracking it at Portland International Raceway on Monday. Why can't this thing be normal for 3 days?

Skunkworks

Given the noise and behavior of your tensioner in the vid, I'd say you have a part(s) failing.

Now I worked with experimental supercharger and input shaft was glass smooth when I turned it by hand. But give it a decent load and it sounded like popcorn just before failure, with very similar belt dynamics as yours. In my case it was internal shaft deflection .

I can't give too much guidance as I'm not there but something is being overlooked.

*I'm sure you looked at all end plays to be analysed.
*Looked at all alignments.
*Looked at belt dust distribution.
*Looked at supercharger for possible binds...

Good Luck,
Mike