Rapping, tapping, clacking sound that won't go away.
01-23-2002, 06:15 PM
#1
Team Owner
Thread Starter
Rapping, tapping, clacking sound that won't go away.
My motor has a sound coming from it that sounds like it's low on oil or a rockers loose. I've isolated it to the #7 exhaust valve. I made sure it had enough oil and adjusted all the valves on the left bank but the noise is still there. Anyone have any clues as to what I should look for next?
01-23-2002, 06:23 PM
#3
Melting Slicks
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Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
I remember with my old Camaro I had a banging noise that sounded like a hammer tapping on the engine. I swore a valve was getting ready to pop through. Turned out to be a crack in the plug wire and it was arcing across to the header :eek: .
I couldn't believe that little crack caused that much noise :crazy:
Probably not that, It would be too easy. Good luck :cheers:
I couldn't believe that little crack caused that much noise :crazy:
Probably not that, It would be too easy. Good luck :cheers:
01-23-2002, 06:40 PM
#4
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Re: Rapping, tapping, clacking sound that won't go away. (n8370c)
I'm pretty sure it's mechanical. I did some ear searching with a stethescope and the loudest point is the exhaust valve on the #7 cylinder.
I keep cringing because I keep thinking of stuff like bent a pushrod or bad lifter.
I keep cringing because I keep thinking of stuff like bent a pushrod or bad lifter.
01-23-2002, 07:37 PM
#5
Burning Brakes
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Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
I had that sound and pulled the heads. Turned out a small piece of metal was hitting the top of #8 and the head. I have no idea how it got into my engine that had 70,000 miles on it.
01-23-2002, 08:02 PM
#6
Racer
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Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
Does the noise change or go away if you pull the plug wire off with engine running ? also check compresion on all cyl.s on that bank to compair them
01-23-2002, 09:27 PM
#7
Team Owner
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Re: Rapping, tapping, clacking sound that won't go away. (kenincanada)
The noise stays the same when I pull the plug wire.
I'll have to wait 'til the weekend to run a compression test.
I'll have to wait 'til the weekend to run a compression test.
01-23-2002, 09:47 PM
#10
Platinum Supporting Dealership
Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
The reason I asked is that I went through hell and mine turned out to be a bad exhaust gasket. BUT it will stop the noise (exactly the sound you describe) if you pull the wire
01-23-2002, 09:49 PM
#11
Platinum Supporting Dealership
Re: Rapping, tapping, clacking sound that won't go away. (Rhys)
Read this http://forums.corvetteforum.com/zerothread?id=162061
http://forums.corvetteforum.com/zerothread?id=173861
[Modified by Rhys, 8:50 PM 1/23/2002]
http://forums.corvetteforum.com/zerothread?id=173861
[Modified by Rhys, 8:50 PM 1/23/2002]
01-23-2002, 10:18 PM
#12
Team Owner
Thread Starter
Re: Rapping, tapping, clacking sound that won't go away. (Rhys)
One of the first things I thought of was an exhaust leak so I snugged the headers up tight. ( I have to do this almost once a month...even with lock washers mine end up loose. ) But now I realize just snugging up the exhaust isn't checking the gasket. (Whoops! :eek: ) The only thing still leaning me away from it being an exhaust leak now with the stethoscope the noise is loudest when it's placed near the exhaust valve on that cylinder. All that being said I'm still gonna pull the header away and check out that gasket.
01-23-2002, 10:49 PM
#14
Team Owner
Thread Starter
Re: Rapping, tapping, clacking sound that won't go away. (Rhys)
I just pulled all the plug wires one by one and the noise was still there. I did notice the motor had to be warmed up before the noise would appear if that helps diagnose.
[Modified by Vfastboy 73, 8:50 PM 1/23/2002]
[Modified by Vfastboy 73, 8:50 PM 1/23/2002]
01-24-2002, 12:14 AM
#16
Platinum Supporting Dealership
Re: Rapping, tapping, clacking sound that won't go away. (kenincanada)
Doubt that if it is in the area of #7.
Well, looks like you are headed down the same path I did. I adjusted the valves first, then replaced pushrod, lifter and rocker.
Well, looks like you are headed down the same path I did. I adjusted the valves first, then replaced pushrod, lifter and rocker.
01-24-2002, 09:52 AM
#17
Burning Brakes
Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
being an L-82 I am going to assume that they are hydrolic lifters. How many miles are on the motor? Hate to say it but it sounds to me like a collapsed lifter, especially if you tried adjusting the valves the the sound did not go away.
Just my.02 hope that I am wrong though
JoeB
Just my.02 hope that I am wrong though
JoeB
01-24-2002, 10:00 AM
#18
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Re: Rapping, tapping, clacking sound that won't go away. (woodworkr)
So you have pulled the valve cover, and checked all the rockers?
If yuo run it that way you can sometimes see a stickey valve, you can also put a finger on each rocker ( or a clean stick if you're chicken :) ) and see if the sound changes...
Oh, it could also be a flat cam lobe...
[Modified by 427V8, 8:01 AM 1/24/2002]
If yuo run it that way you can sometimes see a stickey valve, you can also put a finger on each rocker ( or a clean stick if you're chicken :) ) and see if the sound changes...
Oh, it could also be a flat cam lobe...
[Modified by 427V8, 8:01 AM 1/24/2002]
01-24-2002, 10:04 AM
#19
Burning Brakes
Re: Rapping, tapping, clacking sound that won't go away. (Vfastboy 73)
I've seen it the past on many occasions a little piece of Carbon breaks off the exhaust valve and depending on the size stays in the exhaust chamber and sounds like you just descibed. sometimes it falls into the cylinder, when it does that it will eventually hit the spark plug and distroy it so you will know for sure.
:)
:)
01-24-2002, 12:45 PM
#20
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Re: Rapping, tapping, clacking sound that won't go away. (paso)
My L-48 73 Coupe with only 75K on it had the same type of noise in the same exact area. After driving it a summer like that, I rebuilt the engine to find that the cam lobe was worn really bad causing the noise.
I also just recently purchased an 86 Trans Am with a recenlty rebuilt engine that sounded like a deisel engine, no matter how I tried to set the lifters and no what i did to straighten this problem out. After removing the engine and tearing it down, I found that the valves were smacking the pistons. I don't suspect that you have this problem, but may have a worn cam lobe, if all the easy to check items suggested above come back OK.
Hope its an easy fix!
Be cool!
"TEACH"
I also just recently purchased an 86 Trans Am with a recenlty rebuilt engine that sounded like a deisel engine, no matter how I tried to set the lifters and no what i did to straighten this problem out. After removing the engine and tearing it down, I found that the valves were smacking the pistons. I don't suspect that you have this problem, but may have a worn cam lobe, if all the easy to check items suggested above come back OK.
Hope its an easy fix!
Be cool!
"TEACH"