LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

What is this tapping noise?

Old Aug 29, 2004 | 02:50 AM
  #1  
Gripenfelter's Avatar
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What is this tapping noise?

It comes from the passenger side valve cover.

Its intermittent. About every 5 secs or so.

Its just a single loud tap.

Sometimes followed by a surge in the idle.

My car sometimes idles very low when I slow down to a stop.

I've had the valve covers off and run the car and its none of the rockers. I even loosened and re-tightened the rockers.

It sounds like its coming from right near the top of the valve train or just under them.

Bad lifter?

Showing 1 degree of retard.

Any guesses?
Old Aug 29, 2004 | 03:14 AM
  #2  
94 CAMRO Z28's Avatar
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Re: What is this tapping noise?

My guess would be a lifter on its way out.

Aaron
Old Aug 29, 2004 | 11:43 AM
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Re: What is this tapping noise?

Broken valve spring? I have a double coil.
Old Aug 29, 2004 | 01:27 PM
  #4  
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Re: What is this tapping noise?

I dont know that a broken vavle spring would be intermittent though. I would think you would hear it almost constantly not every 5 sec. or so.

Aaron
Old Aug 29, 2004 | 01:39 PM
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Re: What is this tapping noise?

I'll go check and report back
Old Aug 29, 2004 | 02:27 PM
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Re: What is this tapping noise?

Make that another vote for lifter. Spring should be a constant sound.
Old Aug 29, 2004 | 05:22 PM
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Re: What is this tapping noise?

I would look into that lifter asap. I had a lifter get a flat spot on it. The noise changed with idle. I only put like 30 miles on it after i noticed the sound...bad idea I know...and it ate through the came so I had to get a new one. Pulling the intake manifold off is nothing compared to having to take it apart for a new cam.
Old Aug 29, 2004 | 11:13 PM
  #8  
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Re: What is this tapping noise?

Well its not the valve spring.

Must be the lifter.

I've put well over 200 miles on it. At first it was a very faint tap. Recently its gotten louder. I put probably 30 miles on it after it got loud.

Definately pulling the intake off tomorrow.
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