Engine Knock Advice
Thread Starter
Instructor
Joined: Sep 2006
Posts: 124
Likes: 0
From: Chesapeake VA
Engine Knock Advice
I have a 2000 C5 convertible. Car has an MN6 and about 44,000 miles. When I start the car up after it has run for about a minute and settled into its idle, there is a noticeable metalic knock from the engine that continues but diminishes until the engine reaches NOT. After NOT it is still there but barely noticeable. I have tried 10W30 oil with no change. The engine runs strong and does not burn any or use any oil. It has good oil pressure. I am not sure if it is the dreaded piston slap or a failing lifter. I am considering putting a new cam and lifters in the engine, but if it has piston slap I will probably replace the engine later with an LS6. I don't want to spend the money on a cam and lifters if that won't fix the problem. Is there a noticeable difference between the way an engine with piston slap sounds and a failing lifter?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
A bad lifter would continue to knock or rattle always even after it warmed up--It does sound like the piston slap deal--As far as a cam install--generally the valvetrain noise will get louder than stock after you put one in--The dreaded sewing machine sound--I tried all sorts of fixes and nothing really works--i just got used to it and live with it--
Race Director
Joined: Sep 2004
Posts: 17,786
Likes: 4
From: Redsox, Pats, Celts & Bruins !!! Redsox Nation !!!
St. Jude Donor '06-'07-'08-'09-'10-'11-'12
It sounds like piston slap, but if you still hear it after a good 10 mile drive, it may be a problem.
TTT for ya, hope it works out.
TTT for ya, hope it works out.
Team Owner
Joined: May 2006
Posts: 21,473
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
I believe Piston Slap is more prominent than lifter noise!
You could do the Cam and Lifters and install these back in the new motor when you get one or if it takes care of your problem - Then Problem: Solved!
Just a thought!
Thanks,Matt
You could do the Cam and Lifters and install these back in the new motor when you get one or if it takes care of your problem - Then Problem: Solved!
Just a thought!
Thanks,Matt
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
Here is some reading for you
http://www.pistonslap.com/tsb.htm
and another
http://www.idavette.net/hib/02ls6/page5.htm
http://www.pistonslap.com/tsb.htm
and another
http://www.idavette.net/hib/02ls6/page5.htm
Burning Brakes
Joined: Nov 2002
Posts: 1,018
Likes: 52
From: Deltona Fl.
