redbird555

iTrader: (14)

trust me man its fine... they all do it ls1's more than others as after 03 they changed pistons to help out the noise in all ls/lq motors.

Between my buddies and I we have owned around 10 of these ls cars and worked on many more.... EVERY single one of them with the exception of the 98's and 1 00 had the same noise. We beat them regularly too. The noise comes from the aluminum block and short skirt pistons so its inherent in the deisgn till you change one of those. Even my dads yukon does it (not as loud though) on cold starts its not as noticebale though as iron doesnt expand/contract and has better sound proofing than aluminum does.

The motor in my z28 now came to my with 5500 miles on it from a Z06 and makes the same sound lol. Buy the heads/cam and let er eat

this is one of mine that was bone stock with 100k on it


it was much louder in person, point being i that i ran the crap out of it till 130k then the new owner threw h/c at it for his 69 camaro swap and its running great still

comatoastWS6

Thanks man, thats a good reassurance If I had the means, and room I would have no problem tearing into the motor, replacing pictons rings, hone, timing chain , cam, etc etc, and throw headers on then as well.. But I don't, lol.. It doesn't look like the most fun motor to pull, and I couldn't pay some shop to do it as the labor would be ridiculous.


As for now, I will just keep doing maintenance suspension/chassis mods , get a converter and call it good til next year.. I would really like to make it to the track this year to do a progress log of the mods, to see how my times improve

1st run) stock car, stock suspension/tires
2nd run)+ lid, stall, headers, solid mounts, LCA, PH bar, subframe connectors, tune
3rd run) + cam heads, retune, DRs

RockinWs6

Classic carbon knock............. I call BS on the piston slap.............

Aluminum engines GROW a lot more than cast iron engines. What you are hearing is the built up carbon on the tops of the pistons hitting the cylinder heads UNTIL the engine gets hot and EXPANDS and grows, then the built up carbon no longer can hit the cylinder head. Mosyt dealers offer a REAL carbon cleaning, seafoam etc is complete garbage.



I personally wouldn't touch it, ITS NORMAL and will hurt nothing. Plus you can spend 100 bucks to get it cleaned, 5k miles later its gonna knock again.................

Ask me how I know this? ALL 6 LS1 cars I've owned has had the exact same noise AND a proper carbon cleaning ALWAYS stops it ...for a while.


By the way PISTON SLAP is the biggest bunch of BULL **** you'll ever hear. Its GM excuse for engine noises. If its piston slap its "NORMAL" get it? Some dealers are honest and admit what a nise really IF YOU ARE OUT OF FACTORY WARANTY.

If your Pistons were that loose in the bores to knock that loud it wouldn't last for a 1000 miles....think about it.

Classic BS I took my wifes 01 WS6 in for lifter noise where I bought the car, of course they blamed all the noise on piston slap. Took it to 2 other dealers AND a LS1 shop. It was lifter noise...........

2 things piston slap gets the blame for are 1 CARBON KNOCK 2 LIFTER NOISE.

PISTON SLAP .....SLAP MY AZZ! Piston slap? that much noise if it were loose pistons would NEVER go away hot!

anyone types PISTON SLAP again is gonna get beat up!

ls1 1990 VN

Mine had 'PISTON SLAP' & cold or hot wouldn't go till the engine was rebuilt.
The noise was a loud knocking.
I had been running a cam only TSP 231/237 for a year, put on a set of TSP 5.3 stg 2.5 heads & a day later the noise started.
It just got worse over the next month so the engine got pulled.

RockinWs6

After you measure everything post up pictures................then I'll believe it. Loud knocking could be ANYTHING.

If it is piston slap what happened to make it slap that bad you pulled the engine? Did the piston suddenly wear more? Are these magic pistons? If you did loose a piston<which I seriously doubt > Its almost ALWAYS broken ring lands from running too9 lean etc. PISTON SLAP <if you really have WON"T HURT ANYTHING!

Dam how can this piston slap turn into such BS?

Next piston slap will be blamed for Obama being in office! or the food at Sonic!

redbird555

iTrader: (14)

The ls1 in that video puked a head gasket, took off the heads and the pistons were pretty clean. Soaked them in diesel and got them to sparkle.....still had the same noise until warm.


My basically BRAND NEW ls6 engine with 5500 miles on it did and still does it. The pistons were so clean on that thing you could serve a t-bone on them. So ya I don't buy the carbon thing, great to hear it quieted yours down tho

ls1 1990 VN

This was back in 06, bit hard to measure now. This was a standard engine & had done 30,000km.
So if a piston is slapping around, nothing gets extra wear or hurts anything.
'BULLSHIT'

RockinWs6

I'm not saying there isn't such a thing as piston slap, I'm saying it way over used as a diagnoses. ALL the Ls1 cars have a slight piston noise on cold start, What i'm saying is when ever there is a noise in a LS1 engine the 1st diagnoses is always piston slap.

My 99 ta had 28k on it when it started knocking badly cold, took it to the dealer and of couse they claimed NORMAL PISTON SLAP. They just screwed me around so fk it we drove it till 135k like that until the trans went out. Took it to a different dealer to have the trans fixed and they did a DECARBON service on the engine. WAS QUIET AS A MOUSE after that! You could hear the slight piston noise on cold start up but it DIDN"T KNOCK anymore.


02 Formula 32k had terrible knock cold and of course it was blamed on piston slap. Got screwed around on that the same way............it was dirty lifters and carbon build up.. DEALER CLAIMED you guessed it PISTON SLAP!


01 WS6 36k terrible insane knocking cold plus still had a knock warmed up. Took it back to the dealer about 10 times, every time dismissed as normal piston slap. Took it to 2 other dealers 1st one blamed piston slap AGAIN.....2nd said LIFTERS and the LS1 shop I took it too< STUMPS in Pine Grove> said LIFTERS. Stumped suggested I try some synthetic oil to help clean the lifters. I bought a engine cleaner called RISLONE and started putting that in the engine oil along with having the engine decarboned. Now its quiet like it should be with normal cold piston noise.

They all make slight piston noise cold......if you wanna call it slap????????

Normal piston noise is that slight rocky diesel sound you hear for about 2 mins on a cold start. If you have knock you just can't automaticly blame it on piston slap.....because in order for a piston to actually make a knocking sound it has to be HITTING SOMETHING. ROCKING IN THE BORE only makes for a slight diesel sound.

I know this from years of experience, If anyone claims piston slap and repaired it post up the picture and measurements to prove or blame the REAL cause.

In all the years coming to this site NO ONE has ever pulled a engine for ACTUAL PISTON SLAP and posted up to prove it....I"M WAITING.