Rattling Noise

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Jun 5, 2002 | 03:44 PM

WHRITZY

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Joined: Aug 2001

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From: Atlanta GA

Rattling Noise

When I first got my 90, you could hear what sounded like rocks or marbles in an empty coffee can when you turned off the ignition...just rattled for a second and quit. The car had 23k on it at that time. I figured it was a pre cat or main cat problem and didn't worry about it too much because I knew the mods I was contemplating would solve the situation.

Welll.......my new mods (not yet posted in my signature) include headers (thereby eliminating pre cats) and a new Random Tech High Flow Main Cat...the sound is still there when I turn off the ignition. AND....to make matters worse, now that I have a mild cam in in and the engine lopes beautifully, the damn rattle is present when it's idling (800 rpm) and it's really embarrassing. I have checked all heat shields, etc etc that one usually checks during this sort of thing.

When I get under the car a listen, it really sounds as if the "gurgling" rattle is coming either from area of back of oil pan or in front of transmission. It doesn't make any difference if you have clutch in or not.

Any ideas?

Thanks!

Jun 5, 2002 | 04:19 PM

PeteL

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Joined: Dec 1999

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From: And on the fifth day, subpoenas were served to Obama senior staff

Re: Rattling Noise (WHRITZY)

Could be the PO installed a single mass flywheel?

Jun 5, 2002 | 04:38 PM

WHRITZY

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Joined: Aug 2001

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From: Atlanta GA

Re: Rattling Noise (PeteL)

Pete, don't know for sure....but don't know why he would....car was pure stock when I got it and had 23k on it. Only has 24.5k now.....are you familiar with the noise I'm trying to describe? Go's away at about 1100 rpm....

Jun 10, 2002 | 04:06 PM

captainjack

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Joined: Aug 2001

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From: colorado springs co

Re: Rattling Noise (WHRITZY)

The same noise in my 85 coupe was caused by the dual-walled front Y-pipe. Your car probably has the same type of Y-pipe. GM made the front Y-pipe with one pipe inside the other for a certain length inside the Y-pipe. When the spot welds break down between the two pipes you get the annoying rattle. My exhaust technician blew thru the outside pipe with a torch on both Y sections in about 3 or 4 places on each pipe. He then proceeded to spot weld the inner pipe back onto the outer pipe and filled the holes completely on each pipe. The end result was no more vibration between the two pipes and thus no noise. Hope this is your problem and you get it resolved.

Jun 11, 2002 | 03:27 PM

WHRITZY

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Joined: Aug 2001

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From: Atlanta GA

Re: Rattling Noise (captainjack)

Thanks, Capt. Jack...the theory is good, but I eliminated my front Y Pipe when I installed Hooker Headers with the engine mods....still looking for it...

Jun 11, 2002 | 04:29 PM

devilfish

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From: Sweden/Stockholm

Re: Rattling Noise (WHRITZY)

I got the same noise to. Its the PVC vavle that rattels when you turn of the car and let of som vaccume. Try to take off the pvc valve and start and turn off the car..

Regards