HappySalesman

iTrader: (3)

Hey all

So my LS1 has piston slap, usually it goes away once the engine warms up and I just continue on my merry way.

However recently, I've noticed that between 1000-1500 RPM, usually when the engine is decelerating, I get the same noise. Doesn't matter what temp the engine is at, sometimes occurs when I'm stepping on the gas as well.

Is this something worth being concerned about?

celtsean

iTrader: (1)

My 00 trans am with a magnaflow cat back has made that sound for quite a while. I have a tick at idle , which may or may not be the same sound. Same exact symptons as yours , decelleration,sometimes while gassing it, and 900 to 1400 or so rpm range. I never could figure out if the exhaust drowns it out or if it just stops past that. Strange thing I noticed about mine though , if I take it out of gear (m6)while coming to a stop it still does it. I stopped paying attention to it. It's done it for awhile and car runs strong. So until something else happens due to it ,I now ignore it. The idle tick I will fix, I got some solutions on here . But that , I don't pay it any mind unless it gives me a reason .

MonmouthCtyLS7

iTrader: (6)

Piston slap is pretty normal with these cars, as for the deceleration slap I've never heard thT one. I'd have somebody reputable take a look at it. It could very well be nothing.

RockinWs6

I'll bet its not even piston slap....that term is used for every freakin noise a LS1 has! Piston slap noise is barely noticeable! Its most likely carbon knock or a loose timing or dirty lifter or wrong worn out engine oil you are hearing etc. Also ya know the purge valve mounted on the intake manifold can make ALOT OF TAPPING NOISES.

Think about it how long do you think pistons would last if they were KNOCKING in the bores? Not very long, blue smoke would be pouring out the exhaust pipes!

Honest piston slap is that diesel type sound you hear at 1st start up, If you hear KNOCKING you have other problems.

The reason this stupid piston slap noise BS started is the dealers started blaming every engine noise on piston slap to get out of repairing the REAL troubles. Now EVERYONE says piston piston piston slap....geez H Christ

Example I took my 99 TA back to the dealer under warranty because the lifters were ticking badly......they tried to blame it on piston slap. Took it to another dealer they said bad lifters, took it to a 3rd dealer and they also tried to blame it on piston slap...IT WAS BAD LIFTERS...................

NEXT person posts up PISTON SLAP ......................

RockinWs6

From your description I would guess you are hearing the lifters-valve train load and unload. Try changing oil to any 5-30 then see how it sounds.

BoricuaHec01

It's the piston slap, I seent it.

HappySalesman

iTrader: (3)

I'm actually running 5w-30. Oddly enough I did start noticing it right after I changed my oil, but I used the same Royal Purple stuff I've used since I bought the car. maybe next time i'll try some Mobil 1 or something.

RevGTO

iTrader: (12)

If you're going to change it again before summer, or live in a year-round warm climate, try some Rotella 10-30 and see if it makes a difference.

I used to use Castrol GC synthetic and noticed less valvetrain noise when I switched to dino.

HappySalesman

iTrader: (3)

Yeah I live in the northwest, so summers are pretty hit and miss here, could be 80+ everyday, or 60 lol.

I only thought it was piston slap because it's the same noise the car makes when I first start her up, then goes away after a couple of minutes. I'll take a video sometime

RockinWs6

You are most likely hearing the lifters cold too, they bleed down and are noisy as hell cold until the air gets pushed out of them. Piston slap is more of a diesel engine sound but not very loud.