LS2 Engine Knock
Thread Starter
7th Gear
Joined: Jan 2010
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From: Ofallon MO
LS2 Engine Knock
I have a 2005 that has 23k on it, I'm noticing a knock on cold start that quites as it warms up but doesn't leave. did the old stick on the block trick and it seems the the noise is louder when it's on the water pump. Anyone had a similar problem?
All a quick update, dealer says it's a bearing or scuffed piston...engine needs to be pulled and taken apart for exact problem. URGH! It's under warranty so keeping my fingers crossed it's taken care of. Thanks for all your suggestions, I'll keep you updated should know more by Wednesday once it's out and apart.
All a quick update, dealer says it's a bearing or scuffed piston...engine needs to be pulled and taken apart for exact problem. URGH! It's under warranty so keeping my fingers crossed it's taken care of. Thanks for all your suggestions, I'll keep you updated should know more by Wednesday once it's out and apart.
Last edited by kenvet; Jan 18, 2010 at 05:12 PM.
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From: Machineguns, because I don’t compromise
Most likely piston slap.
It's more common on the gen3 engines. A quick fix is to change the engine oil with one that's a grade thicker. The noise should be reduced to a degree. The cold winter weather isn't helping with the piston to cylinder tolerance either; it's compounding the issue.
Hope this helps.
It's more common on the gen3 engines. A quick fix is to change the engine oil with one that's a grade thicker. The noise should be reduced to a degree. The cold winter weather isn't helping with the piston to cylinder tolerance either; it's compounding the issue.
Hope this helps.
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From: SE Pennsylvania
St. Jude Donor '03 thru '26
Oldtimer
This is VERY common problem, well not so much a problem as a annoyance. It's plain old Piston Slap. My LS1 has done it from the moment I bought my C5 six years ago. The good news is isn't a harmful sort of noise. Ah, and the only thing I've found that works is what a lot of guys at the 'Porsche fourm' have said, (Yes, Porsche engines have this problem too). Try a can of BG44K, I have found that if you pour it in and then fill your tank, the piston slap will be gone somewhere within 250 miles. How long it'll be till it returns is anyone's guess.
The problem is Premium fuel. Carbon build-up happens a lot faster with high-test 98 octane fuel than with 87 octane regular fuel. But using regular fuel in a LS2 Corvette is going to cause a real lack of performance. And I don't know about you, But I didn't buy a Corvette V8 to feed it Chevy Cavalier fuel.
The problem is Premium fuel. Carbon build-up happens a lot faster with high-test 98 octane fuel than with 87 octane regular fuel. But using regular fuel in a LS2 Corvette is going to cause a real lack of performance. And I don't know about you, But I didn't buy a Corvette V8 to feed it Chevy Cavalier fuel.
Tech Contributor
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From: Van Buren Arkansas
Wounded Warrior Escort '11
It happened on my '07 LS2 as well just a couple of weeks ago in very cold weather. I had the oil changed an hour later and it hasn't been heard since. This was all on a trip out to the midwest during the holiday.
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Melting Slicks
Joined: Jun 2009
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From: SE Coast FL
What about the fuel injectors ticking? Could this be what the OP is referring too? Anyway I was told the injector noise was normal also :/ Its almost as embarrassing as squealing brakes!
Last edited by jpuli28; Jan 17, 2010 at 04:27 AM.
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From: Milford NH
Burning Brakes
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From: Cincinnati OH
Being an 05, should the OP be checking the crankshaft pulley.
Search crank pulley for the tsb. Certian early 05's had to have the crank pulley pinned.
The VIN's are listed in some of the search results.
Mike
Search crank pulley for the tsb. Certian early 05's had to have the crank pulley pinned.
The VIN's are listed in some of the search results.
Mike
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From: Brooklyn New York The DVL and the chicken sleep with the fishes....
St. Jude Donor '08
99% its piston slap ... its not "good" , but just let the car warm up and it should be fine . I had it on my 07 , posted about three years ago about it and everyone thought I was nuts , now its coming up on some more LS2's .
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From: Charlotte, NC (formerly Endicott, NY)
You can make things be a lot worse if you try to fix things that aren't broken. Same goes for brake squeal.
Bill
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From: Katy TX
Doubt that is the issue here. That problem usually makes itself known with other noises; typically belt squeal/squeak or a squeaky pulley type sound.
Race Director
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From: SE Pennsylvania
St. Jude Donor '03 thru '26
Oldtimer
The Op said it is a slight 'knock' that he or she hears when the engine is cold and goes away as the engine is warmed up ? That my friend is Piston slap. And I reallly doubt ANY LSX engine doesn't have it at some point. Also there is a good chance he or she hears the injectors ticking or some slight valve train noise.
Thread Starter
7th Gear
Joined: Jan 2010
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From: Ofallon MO
Yes it is really loud when you first start it, it quites down but never leaves...Dealer said today it has to come out and apart won't know until Wednesday what the outcome is. What was wrong with the silverado?
Melting Slicks
Joined: Jun 2009
Posts: 3,142
Likes: 1
From: SE Coast FL
This is VERY common problem, well not so much a problem as a annoyance. It's plain old Piston Slap. My LS1 has done it from the moment I bought my C5 six years ago. The good news is isn't a harmful sort of noise. Ah, and the only thing I've found that works is what a lot of guys at the 'Porsche fourm' have said, (Yes, Porsche engines have this problem too). Try a can of BG44K, I have found that if you pour it in and then fill your tank, the piston slap will be gone somewhere within 250 miles. How long it'll be till it returns is anyone's guess.
The problem is Premium fuel. Carbon build-up happens a lot faster with high-test 98 octane fuel than with 87 octane regular fuel. But using regular fuel in a LS2 Corvette is going to cause a real lack of performance. And I don't know about you, But I didn't buy a Corvette V8 to feed it Chevy Cavalier fuel.
The problem is Premium fuel. Carbon build-up happens a lot faster with high-test 98 octane fuel than with 87 octane regular fuel. But using regular fuel in a LS2 Corvette is going to cause a real lack of performance. And I don't know about you, But I didn't buy a Corvette V8 to feed it Chevy Cavalier fuel.
Just left the dealer and had it examined, GM will not do anything about it, they cant eliminate the problem but deemed it unharmful.
