Clattering noise from the engine.
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Clattering noise from the engine.
I was driving my 78 this weekend and I started to hear a low clattering noise everytime I accelerated.
Then the noise started to get louder and louder.
I turned around and drove home slowly.
Any one who has had this experience before?
Am I looking at a motor rebuild?
Thanks in advance.
~Raj
Then the noise started to get louder and louder.
I turned around and drove home slowly.
Any one who has had this experience before?
Am I looking at a motor rebuild?
Thanks in advance.
~Raj
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Guys..
I would be the happiest man if the clatter was caused due to an exhaust leak.
Do you think exhaust leak would develop slowly as it did in my case?
How do I check for exhaust leak?
I would be the happiest man if the clatter was caused due to an exhaust leak.
Do you think exhaust leak would develop slowly as it did in my case?
How do I check for exhaust leak?
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Also,take a long wood dowel and listen with you ear with other end probing engine block side below heads for internal noises...
What is your oil pressure at idle ???
Rich
Instructor
Joined: Jan 2005
Posts: 149
Likes: 0
From: Allen TX
Probably a rocker arm
You might want to check your rocker arms. People tried to tell me it was a exhaust leak and so I swapped out the gasket, it was a pain.
I have had two rocker arm bust on my 74.
I have had two rocker arm bust on my 74.
Instructor
Joined: Sep 2006
Posts: 106
Likes: 2
From: Pullman WA
I looked for cracks in the manifold, didn't see anything obvious. Jacked it up and found where the manifold attaches to the midpipe there was a good 1/4" gap. I loosened up the retaining bracket and found the metal gasket there was broken in half and crushed. Got a new one (which was a bit bigger, making fitting the pipe back on to the manifold at a bit challenging), put it in and it made a world of a difference.
GM didn't put gaskets between the exhaust manifold and the heads, I don't think it's too uncommon for gaskets to be on there though, as people will often put them on if they had removed the manifolds. If that's the case, could be the gasket has been going bad. I've also read that using gaskets can promote manifolds to warp. Even if they are slightly warped, using a new manifold gasket can fix it.
Even if it's not the problem, It's worth checking for exhaust leaks, doesn't take too long and it can be a quick thing to rule out!
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Racer
Joined: Jan 2007
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From: Ocala FL
Raj
It could be any number of things. most likely culprits in my experience
exhaust leak, preignition (pinging), Valve clatter
You didn't mention if it was only under acceleration, under hard acceleration, or all the time.
Also, does it backfire if you back off the gas suddenly? If it does, definite exhaust leak. If it doesn't that does NOT rule out an exhaust leak.
Most are easy to fix once you determine the cause.
Start by making sure the car is securely "parked". In park or neutral (manual trans), parking brake set, wheels chocked. Start the engine and open the hood to listen for where noise is originating.
You can make a mechanics stethoscope with a piece of tubing. Hold one end close to your ear and move the other from one are to another under the hood until you find the source.
If the clatter is next to exhaust manifold at heads replace exhaust gasket.
At transition from manifold to pipe replace exhaust donut
under valve covers, remove covers and check valve adjustment
Only under hard accelerations CHECK TIMING and adjust
good luck
It could be any number of things. most likely culprits in my experience
exhaust leak, preignition (pinging), Valve clatter
You didn't mention if it was only under acceleration, under hard acceleration, or all the time.
Also, does it backfire if you back off the gas suddenly? If it does, definite exhaust leak. If it doesn't that does NOT rule out an exhaust leak.
Most are easy to fix once you determine the cause.
Start by making sure the car is securely "parked". In park or neutral (manual trans), parking brake set, wheels chocked. Start the engine and open the hood to listen for where noise is originating.
You can make a mechanics stethoscope with a piece of tubing. Hold one end close to your ear and move the other from one are to another under the hood until you find the source.
If the clatter is next to exhaust manifold at heads replace exhaust gasket.
At transition from manifold to pipe replace exhaust donut
under valve covers, remove covers and check valve adjustment
Only under hard accelerations CHECK TIMING and adjust
good luck
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Then it started to get louder and persisted all the time.
It does not backfire. Instead the sound was very persistent and loud.
However I noticed that it kind of stops if I accelerate in a higher gear (4th) at lower speed.
Thanks for your help.
Pro
Joined: Dec 2005
Posts: 675
Likes: 0
From: Kinzers. PA
Well is it the stock manifolds.. If so check for the heat riser valve on the passanger side of the motor. I know mine is broken so when i get the rpms up it pings because the flap is opening and closing.right at the end of the manifold see if you can easily move the heat riser... Sounds like the same problem i have who knows...
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
I am talking about some real loud clattering noise..
People turned around and looked at me on my way home after the clattering started.
It really sounded as if a cylinder got siezed or something. But the car ran fine.
People turned around and looked at me on my way home after the clattering started.
It really sounded as if a cylinder got siezed or something. But the car ran fine.
Race Director
Joined: Feb 2005
Posts: 16,100
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We are all just guessiing here,,,need a source of noise..
Rich
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From: If the world didnt suck, we would all fall off. Troy,Ohio.
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St. Jude Donor '04-'05-'06-'07-'08
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Thanks for all the guess work. It certainly helps me to rule out the easier stuff. It will be a few days before I get to work on the car.
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Problem found (PICS)
The sound was not caused by exhaust leak.
There seems to be a loose plate between the motor and the transmission that's causing the loud clatter.
I am a little shocked because the transmission shell seems to be broken.
Does it look like broken to you guys from the pics?
There seems to be a loose plate between the motor and the transmission that's causing the loud clatter.
I am a little shocked because the transmission shell seems to be broken.
Does it look like broken to you guys from the pics?
Last edited by rajsid; Mar 24, 2007 at 11:25 PM.
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Unless my eyes deceive me,I'd say you have a chunk gone out of your bellhousing....and that "plate" is the dust cover...
You will need a new bellhousing...also,I'd straighten dust cover so it does not contact teeth on flywheel...which it apparently does..
Rich
You will need a new bellhousing...also,I'd straighten dust cover so it does not contact teeth on flywheel...which it apparently does..
Rich
Last edited by rihwoods; Mar 25, 2007 at 12:05 AM.