Common rattles??

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Jun 20, 2008 | 11:34 AM

morleyz

Thread Starter

Instructor

Joined: Dec 2007

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From: Crystal Lake IL

Common rattles??

OK...so when I accelerate from a stop, there's a certain point where something under the car rattles (very loudly actually).

When under the car, I can't seem to find anything loose. I can't get it to rattle when the car isn't actually moving (i.e. revving in the driveway)...so of course this complicates the diagnosis since it only rattles when moving.

It sounds like a piece of loose sheet metal rattling between a loose bolt head and another piece of metal, like a heat shield or skid plate.

Are there any common things I might be missing that are prone to losen up and rattle?

Jun 20, 2008 | 11:52 AM

rihwoods

Race Director

Joined: Feb 2005

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Get good look at exhaust hangers...does not take much movement to cause rattle..

Jun 20, 2008 | 03:06 PM

Toms82

Instructor

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From: Boston Massachusetts

Hi,
If your motor mounts are bad, the motor could rock causing the fan to hit the shroud.
Just a thought.
Tom

Last edited by Toms82; Jun 20, 2008 at 06:10 PM.

Jun 20, 2008 | 03:24 PM

morleyz

Thread Starter

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From: Crystal Lake IL

Quote:

Originally Posted by Toms82

Hi,
If your motor mounts are bad, the motor could rock causing the fan to fit the shroud.
Just a thought.
Tom

I'll check that...but wouldn't I expect the motor to rock quiet a bit while revving in the driveway as well if this were the case?

Jun 20, 2008 | 03:42 PM

greg75vette

Racer

Joined: Jul 2007

Posts: 459

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From: Lindenhurst, Long Island, New York

Quote:

Originally Posted by morleyz

I'll check that...but wouldn't I expect the motor to rock quiet a bit while revving in the driveway as well if this were the case?

But revving in the driveway won't produce the same results because the engine isn't under load. I could be incorrect, but a lot more force will be taxed on the mounts while moving/accelerating. You also mentioned only at certain times you hear the rattle, which could mean a frequency resonance from the mounts or the exhaust.
I would check the mounts, then really shake the exhaust and see if hits anything.
My .02

Jun 20, 2008 | 03:48 PM

pbcanney

Drifting

Joined: Aug 2007

Posts: 1,924

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DEPENDING ON WHATEVER THE YEAR OF THE CAR IS...............

I had a rattle on my 81 that was a loose aluminum shield over the cat

but yours might be a 427 68 BB...