Rattle from underneath off throttle

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Nov 8, 2010 | 11:06 AM

75+78 Corvettes

Thread Starter

Pro

Joined: Mar 2007

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From: Porter TX

Rattle from underneath off throttle

On my 78 L82 4speed whenever I'm driving and let off the throttle I hear a rattle that sounds like its coming from the passenger side underneath the car. As soon as I press the gas a little the sound goes away. It seems to only happen when driving. It does not matter what gear or speed I'm going and it does not change tone.
It's been bugging me since I got the car earlier this year but am figuring out what all repairs I can do this winter.

Nov 8, 2010 | 01:12 PM

wcsinx

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Joined: Mar 2002

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Prob. an exhaust hanger

Nov 8, 2010 | 01:55 PM

phildawg19

Racer

Joined: May 2010

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From: Brookhaven Mississippi

yeah its going to be something to do with your exhaust. clamp is probably loose or you might not have one

Nov 8, 2010 | 02:23 PM

7T1vette

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Joined: Jan 2006

Posts: 37,637

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From: Crossville TN

Exhaust system, heat riser valve (passenger side) spring broken, transmission linkage rattling (if 4-speed). Those are the "Big 3" to check out....

Nov 8, 2010 | 03:09 PM

dochorsepower

Drifting

Joined: Sep 2010

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From: Laguna Niguel California

Also check catalytic converter core. Happened to me recently with aftermarket unit.

Nov 8, 2010 | 04:24 PM

Will's'74VetteL-82

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Joined: May 2010

Posts: 737

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From: Pennington NJ

Quote:

Originally Posted by dochorsepower

Also check catalytic converter core. Happened to me recently with aftermarket unit.

Sometimes a piece will break off and get stuck, and rattle in the cat at certain rpm frequencies.

Also check all of the above advice.

Will

Nov 8, 2010 | 05:06 PM

7T1vette

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From: Crossville TN

Years ago, my brother had a 'cat' in his car...it was sleeping on the warm engine. Not pretty when he started the car...

[it didn't 'rattle', though...]

Nov 9, 2010 | 07:06 AM

ED79

Racer

Joined: Jul 2009

Posts: 336

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From: Asheville N.C.

Also check the heat sheild that's around the cat mine would vibrate.

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Nov 9, 2010 | 02:56 PM

75+78 Corvettes

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Pro

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From: Porter TX

Thanks. I'll check them all out. The car's all original so something may have come loose in 30 something years.

Nov 9, 2010 | 04:48 PM

#10

mj9311

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Joined: Aug 2010

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From: bethpage NY

Quote:

Originally Posted by 7T1vette

Years ago, my brother had a 'cat' in his car...it was sleeping on the warm engine. Not pretty when he started the car...

[it didn't 'rattle', though...]

same thing happened to a buddy of mine... cant imagine it being pretty

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