C5 engine knocks when cold
Racer
Joined: Mar 2010
Posts: 489
Likes: 6
From: Brockton MA
Mine does too. From what I have read is many have piston knock/slap at cold start up and the noise goes away after warm.
How long have you had the vette?
Has it always made the noise?
How many miles on it?
Need more info to help.
How long have you had the vette?
Has it always made the noise?
How many miles on it?
Need more info to help.
Safety Car
Joined: Nov 2002
Posts: 4,394
Likes: 6
From: Melbourne FL
Sounds like normal piston slap. Not much can be done to correct it. But, from what I'm seeing on my own cylinders; it does cause wear over time and now my engine block may need to be replaced due to the damage this "normal" problem has caused over time. 
Race Director
Joined: Oct 2011
Posts: 15,036
Likes: 1,613
From: Holly Springs NC
St. Jude Donor '16-'17,'22,'24
How many miles are on your engine that it caused this problem to be serious?
Safety Car
Joined: Nov 2002
Posts: 4,394
Likes: 6
From: Melbourne FL
Racer
Joined: Feb 2013
Posts: 350
Likes: 0
From: Saratoga NY
Piston slap won't wipe out a cam or lifters. You had something else going on. Piston slap is caused bc the pistons expand when they are heated. The engine and pistons were chosen in a way to provide performance. Let the car warm up before you drive it and you won't have any issues. Even if you don't let it warm up it still won't destroy it. It'll just make noise. Just like your valve springs and injectors.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Drifting
Joined: Oct 2006
Posts: 1,724
Likes: 23
From: Minnesota
Its been several years since I installed my cam (228/232 .571/.573 112) and I HATE it. The valve train sounds like complete $h1t....like a sewing machine about to come apart. Its the worse sound ever. Yes, everything is installed correctly, and the pushrods are the correct length. They are a little louder until they warm up, but the sound never goes away. The engine is quite modified (heads, cam, intake, exhaust, TB, supercharger, etc.) but I'm probably taking the cam out this winter (if I get around to it), I'm sick of the noise....I don't care if I loose a few ponies at this point.
The knock on start up is completely normal (piston slap), my 98 and my bros 04 both do it, and have always done it.
The knock on start up is completely normal (piston slap), my 98 and my bros 04 both do it, and have always done it.
Drifting
Joined: Oct 2006
Posts: 1,724
Likes: 23
From: Minnesota
If that noise bugs you, put headers and a cam in it and it will drive you INSANE! I absolutely HATE my cam....the valve train sounds like a guy holding a tin tray full of pennies while having a seizure. (I got that from someone else with a cam but it hits home for sure).
Last edited by reactor2; Oct 28, 2013 at 11:38 PM.
Drifting
Joined: Jul 2003
Posts: 1,647
Likes: 2
From: Peoples Republik of Kalifornia Ka
