Loud noise on acceleration
Thread Starter
7th Gear
Joined: Oct 2022
Posts: 7
Likes: 0
From: Arizona
Loud noise on acceleration
Does anyone else seem to get a valve sound or maybe a light knock with a little bit of smoke when accelerating hard. I noticed on my recent purchase C5 corvette 82,000 miles that when I get on it at the higher rpm range there is a bit of noise and it's got me concerned, I figured it was a little but of valve tick but im not sure. Is there anything I should know about with these ls1 engines? Is it normal noise or something I should worry about?? Thank you in advance for any help with this.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
How long ago did you get the car? I ask because what you describe could be a lot of things. First, how many times have you filled the tank since you bought it? Perhaps the previous owner was burning 87 octane, and you are experiencing pinging when you get on it. Was the car a garage queen? If it hasn't been driven hard in a while, maybe it's blowing out some build up.
Have you changed the oil yet? Make sure you do that right away. When you are draining that oil put some through a coffee filter, you're looking for sparklie stuff. Also check the oil filter.
Pull the spark plugs, they will tell a lot about what is happening in the combustion chamber.
Have you changed the oil yet? Make sure you do that right away. When you are draining that oil put some through a coffee filter, you're looking for sparklie stuff. Also check the oil filter.
Pull the spark plugs, they will tell a lot about what is happening in the combustion chamber.
Thread Starter
7th Gear
Joined: Oct 2022
Posts: 7
Likes: 0
From: Arizona
How long ago did you get the car? I ask because what you describe could be a lot of things. First, how many times have you filled the tank since you bought it? Perhaps the previous owner was burning 87 octane, and you are experiencing pinging when you get on it. Was the car a garage queen? If it hasn't been driven hard in a while, maybe it's blowing out some build up.
Have you changed the oil yet? Make sure you do that right away. When you are draining that oil put some through a coffee filter, you're looking for sparklie stuff. Also check the oil filter.
Pull the spark plugs, they will tell a lot about what is happening in the combustion chamber.
Have you changed the oil yet? Make sure you do that right away. When you are draining that oil put some through a coffee filter, you're looking for sparklie stuff. Also check the oil filter.
Pull the spark plugs, they will tell a lot about what is happening in the combustion chamber.
Thread Starter
7th Gear
Joined: Oct 2022
Posts: 7
Likes: 0
From: Arizona
I checked the oil yesterday and it maybe 1/4 of a quart low topped it off and still does the same thing. I've heard that the LS1 platform is know for piston slap and If that's the case in kinda screwed u til I can afford to rebuild the motor. If I stay put of it hard it's fine, no noise but where's the fun of that lol
Le Mans Master
Joined: Feb 2021
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Likes: 4,305
From: Florida
2025 Corvette of the Year Finalist - Unmodified
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A little lifter noise is not unusual when the engine is cold, or right after startup. But if you can hear valve train rattle at high rpm over engine and exhaust noise, you should be be concerned. If a piston is that loud, it’s going to fail, also could be a lifter, or bad knock sensor.
Maybe have a someone other than the dealer scope it for knock that’s not being arrested. Another possibility is pull the valve covers and check for loose rockers and pushrods.
Maybe have a someone other than the dealer scope it for knock that’s not being arrested. Another possibility is pull the valve covers and check for loose rockers and pushrods.
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Le Mans Master
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From: Florida
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Race Director
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My 2000 had an audible piston slap in colder weather. If ambient was above 60°-65°, no noise. Bought it on July 3, 2003. First night in September that the low temp got down to 50°, it sounded like a diesel for about 30 seconds, and that's no exaggeration!! I agree with vette4fl, pull the valve covers, soon! It could be a rocker coming loose, or even a broken valve spring. Could also be a big exhaust leak, especially since it seems to be more load dependent that rpm dependent. OP, do you have any codes??? Hold the options button in, and press/release fuel button 4 times within 10 seconds while holding options button in. DIC will start showing codes. Take a video of them with your smartphone. To erase codes, push/release reset, and then hold reset until you get a beep. Then push/release options again to display next code. Repeat until it says no more codes. Make note if they're "H" codes or whether theyre "C" codes, meaning History, or Current. Then press E/M to escape. Hope this helps you out. An old fashioned bottle of dry gas, along with a bottle of Techron, never hurt any C5 ever built.....
Thread Starter
7th Gear
Joined: Oct 2022
Posts: 7
Likes: 0
From: Arizona
My 2000 had an audible piston slap in colder weather. If ambient was above 60°-65°, no noise. Bought it on July 3, 2003. First night in September that the low temp got down to 50°, it sounded like a diesel for about 30 seconds, and that's no exaggeration!! I agree with vette4fl, pull the valve covers, soon! It could be a rocker coming loose, or even a broken valve spring. Could also be a big exhaust leak, especially since it seems to be more load dependent that rpm dependent. OP, do you have any codes??? Hold the options button in, and press/release fuel button 4 times within 10 seconds while holding options button in. DIC will start showing codes. Take a video of them with your smartphone. To erase codes, push/release reset, and then hold reset until you get a beep. Then push/release options again to display next code. Repeat until it says no more codes. Make note if they're "H" codes or whether theyre "C" codes, meaning History, or Current. Then press E/M to escape. Hope this helps you out. An old fashioned bottle of dry gas, along with a bottle of Techron, never hurt any C5 ever built.....
Thread Starter
7th Gear
Joined: Oct 2022
Posts: 7
Likes: 0
From: Arizona
A little lifter noise is not unusual when the engine is cold, or right after startup. But if you can hear valve train rattle at high rpm over engine and exhaust noise, you should be be concerned. If a piston is that loud, it’s going to fail, also could be a lifter, or bad knock sensor.
Maybe have a someone other than the dealer scope it for knock that’s not being arrested. Another possibility is pull the valve covers and check for loose rockers and pushrods.
Maybe have a someone other than the dealer scope it for knock that’s not being arrested. Another possibility is pull the valve covers and check for loose rockers and pushrods.
Le Mans Master
Joined: Feb 2021
Posts: 6,460
Likes: 4,305
From: Florida
2025 Corvette of the Year Finalist - Unmodified
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I will definitely have someone look at it asap. I don't beat on it much at all to begin with but when I have heard the noise its always been after the engine it at operating temps. the only other time I hear it now that I have really been paying attention is right at 2,000 RPMs there is a slight noise but then it goes away once its over that RPM range or until I put my foot in it. I'll also mention that I only hear it under load, if I rev the engine up to those RPMs I cant hear anything that sounds like it does while driving.
Hope it’s a quick fix, and keep us posted.