KNocking sound! Clip Included!

JeffD · Post by **JeffD** » Mon Apr 07, 2008 9:47 am

not really, it can help the lifters on older engines, but won't help piston slap. the only real way to fix it is to renew the clearances between the cylinder wall and the piston with a new bore and pistons to complement it.
Jene, you race your car right? so you would have accelerated wear anyway which is why it's happening @35,000 mi.
Personally I would live with it since it's not really a problem.

jene · Post by **jene** » Mon Apr 07, 2008 10:08 am

well yeah.... i just want to make sure IT IS NOT A PROBLEM... thats all.. hahaha

95Z26beretta · Post by **95Z26beretta** » Mon Apr 07, 2008 12:39 pm

scberetta3800 could not have explained it any better, GM posted a bulletin on their shop tech years ago about that piston slap on cold start up. They did not have any fix for it except replacing the engine, and like mentioned they called the noise normal. After the engine warms up seems to seal the gap and goes away. Every 3100 I have owned has had that noise on cold start up, but never hurt the performance or how it ran.

Mr. Beefy · Post by **Mr. Beefy** » Mon Apr 07, 2008 2:19 pm

Oh yea..... the 3.1 MPFI in my old GT did the same thing too

Doesnt affect anything. What really gets me is that the Corsi didnt make that noise until I changed the oil. Odd....... I used a synthetic so maybe with the next oil change I'm going to use standard oil and seafoam the car. See what happens.

6r8ph1X · Post by **6r8ph1X** » Mon Apr 07, 2008 2:34 pm

lol i didn't have the noise untill my lifters all simultaneously went on me then i got the slap from hell lol. I live with it, and my car's still got awesome acceleration and performance.

jene · Post by **jene** » Mon Apr 07, 2008 3:25 pm

yeah mine didnt happen until i changed oil too.. hmmmmm

I know all about pistons slap and such... only reason for posting this was to make sure thats what it was and not something worse..

fastlane02 · Post by **fastlane02** » Mon Apr 07, 2008 8:27 pm

mmm i say lifter is going bad or piston slap.
you better find the problem before racing season starts.

jene · Post by **jene** » Mon Apr 07, 2008 8:35 pm

I raced it last season like this... im pretty sure it is not the lifters.. like i said i bought them from 3400modified and they were almost new... it is going to be raced like this period... until i get the time to fix it... unless it is nothing i need to worry ab out... i was told before it is the normal knock and it shouldnt be a problem..

oh and today.. the knocking was not so bad... the warmer weather makes it not so bad...

ErichZ26 · Post by **ErichZ26** » Tue Apr 08, 2008 4:03 am

If that does not go away post warmup then it is bad. That video sounds like its a cold start piston slap.

jene · Post by **jene** » Tue Apr 08, 2008 9:57 am

(ErichZ26 @ Apr. 08 2008,03:03)QUOTEIf that does not go away post warmup then it is bad. That video sounds like its a cold start piston slap.
Thank you Erich!! I will pay attention to it. I know before it went away after a few mins.. but now it im not sure.... they other day it seemed to last longer...

THANKS!!

jene · Post by **jene** » Sun Apr 27, 2008 9:44 pm

UPDATE!

No more knocky!! Swapped the head our and its gone!

Connect with your social network account