Mystery Noise

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Mar 19, 2008 | 10:41 AM

Bill Ehri

Thread Starter

Intermediate

Joined: Apr 2006

Posts: 26

Likes: 0

From: Stamford CT

Mystery Noise

My '74 with auto tranny has a noise that sounds like a lifter hanging up. The noise increases with rpm and load on the engine. I can usually activate the noise while the car is standing still by putting on the brake and running the rpms up to about 2500. The noise is less noticeable when the engine has warmed up.

Problem is, it's not coming from the engine but from under the car on the passenger side. I thought it might be the heat riser that was telegraphing back through the exhaust so I wired the riser open and it still made the noise. Natually, when I put the car on a lift it won't make the noise.

This has been going on for a long time. Last year the heads where completly rebuilt and the noise didn't go away.

Any ideas? Thanks, Bill

Mar 19, 2008 | 10:48 AM

jackson

Le Mans Master

Joined: Sep 2001

Posts: 7,739

Likes: 630

From: Unreconstructed, South Carolina

Exhaust leak sound often mimics tapping. Suggest you verify there's no leak at exhaust manifold/downpipe/header.

Mar 19, 2008 | 11:01 AM

BB68Vett

Burning Brakes

Joined: Feb 2001

Posts: 929

Likes: 5

From: Marietta GA

Mar 19, 2008 | 12:51 PM

goinbroke

Burning Brakes

Joined: Jun 2002

Posts: 837

Likes: 3

From: Texas

...and for whatever reason it's usually the rear exhaust port on the passenger side.

Mar 19, 2008 | 01:54 PM

gavanm01

Pro

Joined: Aug 2004

Posts: 562

Likes: 1

I concur. Had the same darn thing happen to me with the exhaust gasket letting go. Thought I had done something realllllly bad. Believe me, I found Jesus again until it was diagnosed. Still go to church and say a novina just for good measure...