bottom end tapping/knocking
Thread Starter
Cruising
Joined: Dec 2004
Posts: 12
Likes: 0
bottom end tapping/knocking
I bought a 2004 c5 2/25/2004 and after driving for a day or so I noticed a lower end noise/tapping/knocking that sounds like a connecting rod or wrist pin , the dealership says that its a normal thing , anyone else got this
Melting Slicks
Joined: Nov 2003
Posts: 3,396
Likes: 2
From: North Manchester Indiana
might be normal for them, but not for any cars I own,, If you have a knock in the bottom end, it usually is not good. I would get a better opinion. In fact, I would want a new motor like right now if my 04 vette had a knock. I would not even want piston slap.
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
Many (if not all) LSx motors are prone to piston slap, especially when cold. If the tapping goes away or subsides after the engine has warmed up you can chalk it up to piston slap and ignore it.
Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
Aluminum motors are designed to be at proper clearances when warm. Thus, cold starts can lead to some piston slap which has no ill effect on the car. In 2002+ cars the pistons are teflon coated to help with this.
Since adding LT headers it car is very noise and I just write any semi-odd noises off to exhaust pulses.
Since adding LT headers it car is very noise and I just write any semi-odd noises off to exhaust pulses.
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Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
You have the dreaded piston slap which some late model vettes as well as other late model General Motors engines have. There was a thread a month ago with a link to an interesting article on piston slap. Do an advanced search on "Piston Slap" and you will find all kinds of posts worth reading. Piston slap won't hurt your car but its annoying and sounds like crap. I'm sure it can affect re-sale value too. I know when I was looking for a used C5 I found a couple with low mileage with piston slap, I stayed away from them. Here is a link I found on the piston slap. This sould confirm what you have and probably what you don't want to hear. I would not be a happy camper myself 
http://www.pistonslap.com/
http://www.pistonslap.com/
Last edited by David426; Dec 27, 2004 at 02:46 PM.
