Engine noise
Thread Starter
Intermediate
Joined: Aug 2001
Posts: 47
Likes: 0
From: Royse City Texas
Engine noise
Help! My baby is sick!
I have developed a noise from the engine that is very noticeable when the engine is cold and also when the idle speed is very low(500-700rpm). It gets quieter after the engine has warmed up or the engine speed is increased over 1500rpm but is still noticeable.
Any ideas on how to figure out if it is valve train noise or if I have a piston/rod problem.
Thanks in advance for any suggestions.
David
I have developed a noise from the engine that is very noticeable when the engine is cold and also when the idle speed is very low(500-700rpm). It gets quieter after the engine has warmed up or the engine speed is increased over 1500rpm but is still noticeable.
Any ideas on how to figure out if it is valve train noise or if I have a piston/rod problem.
Thanks in advance for any suggestions.
David
Safety Car
Joined: Sep 2000
Posts: 4,679
Likes: 6
From: Charles Town WV
Re: Engine noise (countryvette)
Generally valvetrain noise will be a clicking sound. Anything in the lower rotating assembly will make noises similar to someone beating on the side of your block with a hammer. Knocking is called knocking for a reason. It's not a ticking, but thumping coming out of the bottom of the engine.
From your description it sounds like you have a bad lifter or a loose rocker arm from your description. Does the sound ever completely go away?
From your description it sounds like you have a bad lifter or a loose rocker arm from your description. Does the sound ever completely go away?
Pro
Joined: Jun 2001
Posts: 579
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From: Pflugerville/ Colllege Station TX
Re: Engine noise (Steve Straus)
What causes knocking exactly and is there anything that can be done short of a rebuild. Im going ot rebuild soon but is there any way i can put it off a little longer.
Platinum Supporting Dealership
Joined: Dec 1999
Posts: 6,425
Likes: 1
From: Traveling the US
Re: Engine noise (Jester69Stingray)
Check your exhaust gaskets. I just spent weeks trying to fix a severe engine knock that I was SURE was some metallic knock in the engine. Never been so sure about anything. Guess what. A $5 exhaust gasket fixed my problem.
Melting Slicks
Joined: Nov 2000
Posts: 2,663
Likes: 3
From: Palm Harbor FL
Re: Engine noise (countryvette)
Have you tried getting a stethescope or some similar contraption (the old screwdriver to the ear or hose in the ear) and isolating where the noise is coming from?
Thread Starter
Intermediate
Joined: Aug 2001
Posts: 47
Likes: 0
From: Royse City Texas
Re: Engine noise (countryvette)
Steve
After reading your post I listened very close and it sounds like the noise is on the drivers side so I tried adjusting the drivers side valve train with no change in the noise. It does sound like a knock instead of a ticking sound but by focusing on one of the rocker arms and listening to the knock they seem to be at the same rate.
The sound does seem to vanish after 2000rpm.
Thanks
David
After reading your post I listened very close and it sounds like the noise is on the drivers side so I tried adjusting the drivers side valve train with no change in the noise. It does sound like a knock instead of a ticking sound but by focusing on one of the rocker arms and listening to the knock they seem to be at the same rate.
The sound does seem to vanish after 2000rpm.
Thanks
David
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Re: Engine noise (Rhys)
Same here thought my engine was toast but was heat riser gasket even after replacing gasket still had noise. Then I bought a new heat riser and gasket and now shes quiet as a mouse. Seems heat riser was warped.
Good luck
Good luck
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Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Re: Engine noise (countryvette)
use a stethascope and a timing light to help determine the source and frequency of the noise. try it on different cylinders. also, pull the plug wire from each cylinder, one at a time- if the noise stops, it could be a rod bearing.
Thread Starter
Intermediate
Joined: Aug 2001
Posts: 47
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From: Royse City Texas
Re: Engine noise (countryvette)
Rhys
I have not thought of the exhaust gasket. I will pick a set up and try that this evening. Thanks
79MakoL82
I will pickup a section of hose and give this a try this evening also.--Thanks
David
I have not thought of the exhaust gasket. I will pick a set up and try that this evening. Thanks
79MakoL82
I will pickup a section of hose and give this a try this evening also.--Thanks
David
Platinum Supporting Dealership
Joined: Dec 1999
Posts: 6,425
Likes: 1
From: Traveling the US
Re: Engine noise (countryvette)
Check this out. If it IS and exhaust gasket, it should be easy to tell.
Look at all the troubleshooting I went through http://forums.corvetteforum.com/zerothread?id=162061
[Modified by Rhys, 11:43 AM 11/6/2001]
Look at all the troubleshooting I went through http://forums.corvetteforum.com/zerothread?id=162061
[Modified by Rhys, 11:43 AM 11/6/2001]
Safety Car
Joined: Sep 2000
Posts: 4,679
Likes: 6
From: Charles Town WV
Re: Engine noise (Rhys)
I hear you guys about the exhaust gasket, but a true "knock" doesn't sound like popping or clicking like exhaust would. It sounds like a 500 lb gorilla beating on the side of your block with a 10 lb sledge hammer. It's the most horrible gut-wrenching sound you've ever heard. When lower rotating parts start go go, it's very obvious.
--
Steve
--
Steve
Le Mans Master
Joined: Sep 2000
Posts: 6,036
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From: Westfield Indiana
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Re: Engine noise (Steve Straus)
I know that gut wrenching feeling. I had been drag racing one night and the next morning I started the vette and it had this terrible sound. Turned out the fan was just catching the bottom lip of the shroud but it was enough to scare the crap out of me. Apparently the shroud had shifted from all of the runs but the fan didn't start catching until the next morning. I can't describe how relieved I was when I found the problem.
Race Director
Joined: Oct 2000
Posts: 17,102
Likes: 7
From: Fair Oaks, OK
Re: Engine noise (countryvette)
I know I need to replace my exhaust gaskets. I did them once on a '69 chevelle and that was a PITA. How hard of a job is doing the same on a '79 Corvette w/ original exhaust manifolds and all the smog crap?
Thread Starter
Intermediate
Joined: Aug 2001
Posts: 47
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From: Royse City Texas
Re: Engine noise (countryvette)
Here is an update after spending the evening troubleshooting the noise.
I replaced the exhaust gaskets with no changes unfortunately. I then unplugged each spark plug wire one at a time and started the engine and the sound remained throughout the test. I then used a piece of hose and tried to isolate the area of the noise and it seemed to be all over the engine.???? The rate of the sound appears to be at the same rate as the valves.
If it is a piston/rod/main problem would the noise be twice the rate of the valves?
The engine has about 5000 miles on a rebuild.
Confused!!
David
I replaced the exhaust gaskets with no changes unfortunately. I then unplugged each spark plug wire one at a time and started the engine and the sound remained throughout the test. I then used a piece of hose and tried to isolate the area of the noise and it seemed to be all over the engine.???? The rate of the sound appears to be at the same rate as the valves.
If it is a piston/rod/main problem would the noise be twice the rate of the valves?
The engine has about 5000 miles on a rebuild.
Confused!!
David
Melting Slicks
Joined: Nov 2000
Posts: 2,663
Likes: 3
From: Palm Harbor FL
Re: Engine noise (countryvette)
If it's valve train related, I would think that you could isolate it to one side or the other with the ole screwdriver to the ear trick (sharp end on the valve cover, blunt end to your ear) :lol:
Platinum Supporting Dealership
Joined: Dec 1999
Posts: 6,425
Likes: 1
From: Traveling the US
Re: Engine noise (countryvette)
Are your exhaust manifolds' connections to the exhaust pipe tight and sealed?
After you check that, I would say, adjust the valves with the engine running next, then move to rockers/lifters.
Can you tell if it is from one side of the engine or not?
One of the suggestions I had (because your knock goes away at higher rpm) is that you have a bad lifter that is collapsed and when you raise the rpm, it finally pumps up. It was suggested to me to try a very heavy oil.
Note: I am no engine expert, but I went through this whole exercize a couple weeks ago with Tom454 and Lars' (and a lot of other's) help
[Modified by Rhys, 10:02 AM 11/7/2001]
After you check that, I would say, adjust the valves with the engine running next, then move to rockers/lifters.
Can you tell if it is from one side of the engine or not?
One of the suggestions I had (because your knock goes away at higher rpm) is that you have a bad lifter that is collapsed and when you raise the rpm, it finally pumps up. It was suggested to me to try a very heavy oil.
Note: I am no engine expert, but I went through this whole exercize a couple weeks ago with Tom454 and Lars' (and a lot of other's) help
[Modified by Rhys, 10:02 AM 11/7/2001]
Moderator
Joined: Jun 1999
Posts: 7,117
Likes: 51
From: Dove Mountain Arizona
Re: Engine noise (countryvette)
Put the hose down by the fuel pump. Happened to me once. Also something that happened on my chev truck once was the flex-plate (flywheel) on the trans developed a crack and when it flexed, mostly at idle, the darn thing sounded like a rod bearing was out. I replaced all bearings with no difference in sound before someone suggested the plate. Put in a new one and it ran quieter than I could believe. If you have a new engine with only 5K on it, it sounds like something else to me. :yesnod:
