engine knock in 2008 LS3
Thread Starter
4th Gear
Joined: Nov 2010
Posts: 4
Likes: 0
engine knock in 2008 LS3
Has anyone been succesful in getting a chevy dealer to repair a bad engine slap, or piston slap? This happens when cold start for a period, sounds like a cummins with a load knock. HELP
Burning Brakes
Joined: May 2010
Posts: 1,167
Likes: 2
From: Pittsburgh Pa
Ehhh...C6/C5...what's the difference.
I can say one thing, my car slaps like hell and I hate it. I've had many built motors in my life and they didn't even slap like these LSx's do. Once I hit 165 degrees it purrs, but before that it's all clatter. Common problem...what can you do really? It's a well documented issue and really has no ill effects on an engine, you just would preferrably not whip the car cold. I putt around until I hit 155 or so, then start to get moving a little more. I can say though, it's really a quirk of these cars I could do without.
I can say one thing, my car slaps like hell and I hate it. I've had many built motors in my life and they didn't even slap like these LSx's do. Once I hit 165 degrees it purrs, but before that it's all clatter. Common problem...what can you do really? It's a well documented issue and really has no ill effects on an engine, you just would preferrably not whip the car cold. I putt around until I hit 155 or so, then start to get moving a little more. I can say though, it's really a quirk of these cars I could do without.
Melting Slicks
Joined: Sep 2007
Posts: 2,599
Likes: 1
From: Long Island, Nassau County New York
Ehhh...C6/C5...what's the difference.
I can say one thing, my car slaps like hell and I hate it. I've had many built motors in my life and they didn't even slap like these LSx's do. Once I hit 165 degrees it purrs, but before that it's all clatter. Common problem...what can you do really? It's a well documented issue and really has no ill effects on an engine, you just would preferrably not whip the car cold. I putt around until I hit 155 or so, then start to get moving a little more. I can say though, it's really a quirk of these cars I could do without.
I can say one thing, my car slaps like hell and I hate it. I've had many built motors in my life and they didn't even slap like these LSx's do. Once I hit 165 degrees it purrs, but before that it's all clatter. Common problem...what can you do really? It's a well documented issue and really has no ill effects on an engine, you just would preferrably not whip the car cold. I putt around until I hit 155 or so, then start to get moving a little more. I can say though, it's really a quirk of these cars I could do without.
Cruising
Joined: Nov 2012
Posts: 10
Likes: 0
My 2008 LS3. GM replaced the lifters. that didn't work.
GM replaced the camshaft assembly and lifters, removed excessive carbon from pistons, fuel injection bulletin- guess what, the knocking is still there.
A deep knock at start up, engine runs rough, lasts well over a minute; sounds similar to a diesel, so I gotta say, "that aint normal."
GM is looking at it again
My suggestion, Persist. By the way, anyone who says knocking is normal and doesn't degrade are incorrect. If the engines didn't require oil, then no problem, but the knocking is telling you tolerances are off and the banging between surfaces does degrade each, the law of physics and materials tells us that. So, on the immediacy maybe no problem over time come on
GM replaced the camshaft assembly and lifters, removed excessive carbon from pistons, fuel injection bulletin- guess what, the knocking is still there.
A deep knock at start up, engine runs rough, lasts well over a minute; sounds similar to a diesel, so I gotta say, "that aint normal."
GM is looking at it again
My suggestion, Persist. By the way, anyone who says knocking is normal and doesn't degrade are incorrect. If the engines didn't require oil, then no problem, but the knocking is telling you tolerances are off and the banging between surfaces does degrade each, the law of physics and materials tells us that. So, on the immediacy maybe no problem over time come on
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Safety Car
Joined: Apr 2007
Posts: 3,582
Likes: 137
From: SoCal CA
Depends if youre still under warranty. If not it will cost a fortune for them to even diagnose it. A bottom end knock is not normal at all, especially if it sounds like a diesel. If your warranty expired them I would recommend to find a good shop familiar with LS motors to diagnose it. I would not go to a dealer after warranty. Usually that sound is associated with the rod bearings which are not the greatest oem.
Cruising
Joined: Nov 2012
Posts: 10
Likes: 0
I have audio. I placed a recorder on top of the engine, underneath the engine and in the cabin. Definitely can hear the clang clanging
As I mentioned previously, if under warranty, persist for the tech's will start it the next morning not hear it and say nothing's wrong. My audio's fixed that problem
As I mentioned previously, if under warranty, persist for the tech's will start it the next morning not hear it and say nothing's wrong. My audio's fixed that problem
Melting Slicks
Joined: Aug 2008
Posts: 3,451
Likes: 27
From: Bay Area CA
Cruising
Joined: Nov 2012
Posts: 10
Likes: 0
Video won't do you any good. The valve train issue is a tear down of which you will not be able to determine anything by a video. You can change the lifter to ls7 but with the variable timing of the ls3 you're fooling around with kabooms.
I'd suggest you take it to a non dealership corvette shop. That's where the motor heads are that can determine your situation and get er fixed.
GM mechanics are bumper to bumper now. So today he works on a malibu, tomorrow your vette- hey they're all the same, they burn gasonline they say. Don't fool around with it if you don't know what you're doing for a crate is $13500 plus install
Good luck
I'd suggest you take it to a non dealership corvette shop. That's where the motor heads are that can determine your situation and get er fixed.
GM mechanics are bumper to bumper now. So today he works on a malibu, tomorrow your vette- hey they're all the same, they burn gasonline they say. Don't fool around with it if you don't know what you're doing for a crate is $13500 plus install
Good luck
Cruising
Joined: Nov 2012
Posts: 10
Likes: 0
So what is your point that is helpful. I'm finding these forums are becoming places to.....
By the way, "these motors" are NOT "crazy noisy." They're smooth, fluid power engines through the range. Sounds like you have a diesel and weren't told about it
And as to the cam swap, the lift and rise, the lifters all have a synergy as well; yes they complement each other to deliver fuel and remove fuel remnants and burnt gases. So I don't understand how you can throw a comment out there that by replacing a component of a tested design, that it will be worse than the malfunctioning one that was replaced because it was bad
I'm a bit rankled in that I posted to seek help. What I've gotten is "crying in the beer", complaining and assumptions that do not pass the test of hey that might be a solution. That doesn't solve the comments and neither do yours.
I'd suggest if you're drinking heavily or smoking something you stop. Its messing with the ability to analyze, evaluate and solve
But thanks for responding.
By the way, "these motors" are NOT "crazy noisy." They're smooth, fluid power engines through the range. Sounds like you have a diesel and weren't told about it
And as to the cam swap, the lift and rise, the lifters all have a synergy as well; yes they complement each other to deliver fuel and remove fuel remnants and burnt gases. So I don't understand how you can throw a comment out there that by replacing a component of a tested design, that it will be worse than the malfunctioning one that was replaced because it was bad
I'm a bit rankled in that I posted to seek help. What I've gotten is "crying in the beer", complaining and assumptions that do not pass the test of hey that might be a solution. That doesn't solve the comments and neither do yours.
I'd suggest if you're drinking heavily or smoking something you stop. Its messing with the ability to analyze, evaluate and solve
But thanks for responding.
Team Owner
Joined: Jul 2012
Posts: 34,479
Likes: 532
From: Central PA. - - My AR15 identifies as a muzzleloader
I believe in the Beer Fairy
The most expensive part of the fix is the gasket set. Go get a price on that, pull the motor, tear it down, pick up a set of pistons, get the thing bored and stick em in. Slap it back together and you're back in business. Gaskets should be about $550, Parts and labor should be next to nothing, pistons and bearings are cheap and so is machine work. Start with a piston that's round and cylindrical, stick it in a hole that's round and cylindrical, and the noise will be gone. There's no easier fix, and it ain't goin away without help.
Safety Car
Joined: Apr 2007
Posts: 3,582
Likes: 137
From: SoCal CA
Video won't do you any good. The valve train issue is a tear down of which you will not be able to determine anything by a video. You can change the lifter to ls7 but with the variable timing of the ls3 you're fooling around with kabooms.
I'd suggest you take it to a non dealership corvette shop. That's where the motor heads are that can determine your situation and get er fixed.
GM mechanics are bumper to bumper now. So today he works on a malibu, tomorrow your vette- hey they're all the same, they burn gasonline they say. Don't fool around with it if you don't know what you're doing for a crate is $13500 plus install
Good luck
I'd suggest you take it to a non dealership corvette shop. That's where the motor heads are that can determine your situation and get er fixed.
GM mechanics are bumper to bumper now. So today he works on a malibu, tomorrow your vette- hey they're all the same, they burn gasonline they say. Don't fool around with it if you don't know what you're doing for a crate is $13500 plus install
Good luck
Last edited by C5Natie; Dec 13, 2012 at 01:39 PM.
Team Owner
Joined: Jan 2007
Posts: 29,065
Likes: 1,839
From: cookeville tennessee
The most expensive part of the fix is the gasket set. Go get a price on that, pull the motor, tear it down, pick up a set of pistons, get the thing bored and stick em in. Slap it back together and you're back in business. Gaskets should be about $550, Parts and labor should be next to nothing, pistons and bearings are cheap and so is machine work. Start with a piston that's round and cylindrical, stick it in a hole that's round and cylindrical, and the noise will be gone. There's no easier fix, and it ain't goin away without help.
Just trying to be funny here correct. NOT 