That does sound like a harmonic balancer. Here are some old threads on the subject...
I've had to have a harmonic balancer replaced. It made a thwoop-thwoop
noise (Ok enough laughing). The outer pulley separated from the inner
crank and the pin that holds them together through the rubber was making
noise. It made more noise at idle.
I replaced my supercharger at 175000kms because it was making noise.
There was a lot of play in both bearings. Finally I replaced the catalytic
converter and that quieted everything down.
On Mon, 29 Oct 2001, Wesley Combs wrote:
> Hey has anyone had anytrouble with the Harmonic Balancer on their
> Bonneville? About 2 months ago the car started making alot of noise and I
> determined that it was coming from the supercharger nose piece so I replaced
> that and still have a noise. Then I replace the top Idler pulley and still
> have a noise. The bottom Idler pulley is making some noise but I noticed
> that the Harmonic Balancer has some rubber on it and that rubber is rotting
> and it almost sounds as if the sound is originating from that piece. Any
> body replaced this? Any input is appreciated.
Subject: RE: [bonneville] 1991 SSE Need help with noise in engine
>Date: Tue, 27 May 2003 01:05:33 -0000
>Subject: [bonneville] 1991 SSE Need help with noise in engine
>Hi Everyone, I'm Vern'* wife and we need help with our SSE. We have
>a strangle rattling sound in the engine (thought it was the water
>pump). We replaced the water pump and it still continues. However,
>it goes away above idle. Also, is the harmonic balancer suppose to
>move back and forth by hand with the engine shut down? Vern'*
>sitting on the couch trying to figure this thing out (lol) HELP!!!!!
The damper'* toast. Known problem and it happened to my '95 SSEi. 8^(
If you get the p/n from your dealer and shop around on-line from places
like Flow Chevrolet and Chuck Hutton you can save some money; when I did
mine last year I think I paid around $120 for a new damper. Good luck!
Subject: RE: [bonneville] Clunks and Other Various Noises
Good to hear from you!
First thing to check for clunk is the sway bar end links. I had to replace
mine. Also the sway bar mounts to the chassis. The struts are probably OK,
however if they didn't change the strut rotator bearings when the struts went
in, that could be it. I had the bearings go bad and replaced the struts then,
even tho the struts were still good. It'* the labor factor...
Failing alternator makes a whine proportional to RPM. Water pumps reported to
leak before full failure. I changed min as a precautionary measure at 110K. Low
rattling noise is highly indicative of a harmonic balancer failure. If it goes
away at higher RPM that'* it.
Supercharger oil never has to be changed according to Magnuson. I'd think once
a year is plenty even for the paranoid.
I sold my Bonne but I'm still answering questions to spare folks what I went
thru. BTW, '92 SSEi mint shape wait many new parts sold for $ 6800. with
From: exoticmwa@a... [mailto:exoticmwa@a...]
Sent: Monday, March 13, 2000 8:13 PM
Subject: [bonneville] Clunks and Other Various Noises
Last thing I replaced on my Bonnie was the struts. Now the thing is making a
clunking noise - sounds like the passenger side front and rear. One mechanic
told me to have Tires Plus (the ones who replaced the struts) pull the strut as
it could be bad. Has anyone ever had a strut go bad after a few weeks?? I've
had everything else looked at.
Also, a mechanic said that the noise coming from my exhaust could be either the
alternator or water pump. When I mentioned the supercharger he shook his head
and said that wasn't it cause he owns one. Not sure what he'* talking about but
it'* kind of a low rattling noise. When an alternator or waterpump goes out does
it actually made noise coming out of the exhaust. I sure don't remember that in
any other cars.... He said pray that its the waterpump cause the alternator is
BTW, I replaced my supercharger oil again. I'm thinking about doing it 2-3
times a year. Does that sound excessive???? Paranoia will do that to you.