Hey guys I am having a slap noise coming from my engine right after start up, usually until the engine warms up and it only does it right around 3 k rpms or higher. I was just wondering what piston slap is exactly and is it really bad for the motor?? Thanks alot, Dustin.

 

Here's a good explanation.

 

Mind you. I don't know, but when LS1 owners complained of this, I (probably wrongly) just assumed that it was because of the all aluminum block. Again, probably wrongly, I assumed that becuase of the different rates of expansion of other metals with aluminum that piston slap woul be more pronunced than would be with an iron block.

But since your's IS an iron block, my guess would be that your cylinders are merely worn and your piston isn't as snug as it was when fresher. Just a guess.

 

Hhmmm, this is all a suprise to me bc my engine has less then 4,000 miles on it since the rebuild. I didnt rebuild the engine, I bought it remanufactured through Recon. It has only come along since it started getting cooler oustide. It completely goes away after the engine warms up for a few minutes.

 

I guess I'd just think that maybe the rebuild process didn't do as good a job as GM and the tolerances are a bit on the high side. Probably not going hurt anything except can be annoying.

I'd check with the vendor to see if they have anything to add. And while you are at it, keep records of your contact so that you have something to back you up if your engine prematurely goes south. Include your posts and reponses on these sites. JMHO

 

I think we may have found the problem... I've never heard a single good thing about this shop.

 

Forged pistons may have some slap upon cold start-up until they warm up a little, It's normal in some motors depending on what your clearances are.

 

Well let me tell u, there customer service sucks very bad. If this one happens to go then I will prolly just build a stroker or something. I make sure not to beat on it at all until the slap has completely gone away.

 

what viscosity oil are you using this could also be the sound your lifters are making.. Sometimes lifters get touchy in the cold especially if you have a thicker weight oil in there

 

Piston slap is completely normal on a cold start up. Happens to me every morning (when the temp drops below 10* C) Goes away after about 5 min of driving.

 

Yea i was thinking it was normal also. It hasnt started doing it till its been getting cooler outside. It completely goes away after a few minutes. I figure as long as it goes away after the engine warms up then it shouldnt be too bad.

 

are ur pistons forged? if so piston slap is normal until ur motor heats up a bit...

this is the reason why GM will never put forged pistons on their stock motors cuz of piston slap...

once my motor is done i'll prolly let it idle for a min til the things warm up in there, and take the RPMS not so high for bout 2-3 more mins...

but FYI, with forged pistons, piston slap isnt a huge issue unless its insanely loud/high repeatity (is that a word? haha)