"Like a Knock" "Oh that Piston slap"

[capriceman]

http://www.pistonslap.com/

I didnt know it was that big of a problem.

go to sound pictures and listen to the clip it sounds lie a big rig.

[Sixty8panther]

Sucks.

[Drew Dowdell]

not new

[pow]

I'd do it the Honda way by extending their warranties or buying back the cars or something to silence the negative publicity. Normally when the transmission of, say, a post-warranty Odyssey blows up, Honda will more than likely quietly repair it as a gesture of "good will".

[ocnblu]

GM does goodwill repairs as well if necessary. This guy is just an ass trying to advertise his business. OK, so why keep it? Attention whore indeed.

My '02 Silverado had a bit of this problem, but only when cold. It quickly cleared up when warm. I still see that truck around town from time to time. The dude's a Boy Scout leader or something. I talked to him one time when he had the truck parked in front of the local Lowe's with a hot dog wagon hitched to it for a Boy Scouts function. He loves the truck and I'm confident after meeting him the thing will run forever. I miss it.

[Mike The Canadian]

dude my century has piston slap aswell, and theres nothing wrong with it. Ferrari's with forged pistons have piston slap, though it's MUCH harder to hear, thanks to good old loud exhaust

It's just a sound, one of the points on the site is "It's embarrassing"

...pffft...

[Camino LS6]

Many,many, of the LSx engines do this. It shouldn't be there,true, but seems to have NO effect on longevity or any other important aspect of engine performance. It is annoying and GM needs to be sure something like this doesn't happen ever again, but it really is just a noise.

[capriceman]

I was reading somewhere on the web to that the knocking goes away after the engine warms to operating Temp.

[Mike The Canadian]

I was reading somewhere on the web to that the knocking goes away after the engine warms to operating Temp.

thats correct, the pistons expand to take up the entire cylinder, eliminating the piston slap once the engine is warm.

[Guest YellowJacket894]

<{POST_SNAPBACK}>

Did the guy actually put that on the back of his Tahoe? What a whiney little bitch!

[capriceman]

Did the guy actually put that on the back of his Tahoe? What a whiney little bitch!

I know we all get a lemon once in a while.

[ocnblu]

Piston slap does not a lemon make.

[Whistler]

Is piston slap actually a problem? I know it sounds bad, but it doesn't actually do any damage or anything does it? And it goes away when a car warms up.

Cosmetic issues don't make a car a lemon...

[Turbojett]

Did the guy actually put that on the back of his Tahoe? What a whiney little bitch!

agreed. he needs to get over himself.

[Sixty8panther]

Don't worry, he'll be drivig a sludged up POS Sequoia soon proclaiming how happy he is wiht his new Eco-Friendly SUV that gets about 15% less real world fuel economy than the Tahoe.

[Nick]

from what it says on that website, these are the problems with piston slap...I for one don't know much about piston slap, so I can only go by what I read or hear...what's your guys take on these issues?

bullet

A loud embarrassing and annoying internal engine knock. Many are defective due to design and manufacturing quality consistency problems. Listen to piston slap here.

bullet

Higher than normal levels of wear related materials in oil analysis samples performed by independent laboratories.

bullet

Vertical piston and cylinder wall scuffing/scratching or scoring on the hammering (noisy) cylinders upon visual inspection. See photos here.

bullet

Reduced combustion chamber compression on the hammering (noisy) cylinders.

bullet

Increased oil consumption.

bullet

Increased exhaust emissions.

bullet

Did GM or there agents tell you they would fix your defective vehicle in writing/and/or verbally when the phantom "New Piston" fix WAS TO arrive in the spring or summer of 2002? GM did in fact admit it had a problem and that its engineering department was working on the fix. The fix was promised to be made to consumer’s engines in the spring or summer of 2002. As the number of slapping engines grew and the cost to repair them grew as well, GM changed its policy.

[funkypunnk]

As an experienced and once Master Cert mechanic I will tell you that it is NOT just a noise.

Piston slap happens due to excessive clearances between the piston and cylinder walls. This normally was not an issue in the old days as pistons had at least partial skirting or even full skirting. Manufacturers in their quest for performance and emissions qualifications have either removed or at least reduced the skirting from the pistons. This now allows the piston to "walk" up and down the cylinder. The reason it goes away when the engine warms up is the piston expands and takes up some of the gap. With metallurgy where it is now, they could fix the problem fairly cheaply by lengthening the skirts on the pistons, but that would add 5.00 per vehicle and take 5hp. They are not willing to do that as 5.00 times 700,000 V8s is alot of money.

Good engines DO NOT HAVE PISTON SLAP!!!!! I have never had piston slap on any engine I have built. This is an easy problem to fix, but GM and others are not willing to fix it. They should extend the engine warranty to 100,000 miles. I will be trading in my Avalanche for this very reason as it sounds like a friggin diesel when it's cold.

He's not whining, you all are a bit under-informed and just taking GM's side in this issue but he is right.

[cmattson]

One might note that the Tundra is plagued by engine-knock as well.. do a google on Tundra + engine knock .. suprised, huh? It seems like everybody just wants to slam GM..

[ToniCipriani]

I'd do it the Honda way by extending their warranties or buying back the cars or something to silence the negative publicity. Normally when the transmission of, say, a post-warranty Odyssey blows up, Honda will more than likely quietly repair it as a gesture of "good will".

I don't understand why this guy would go through so much trouble making the vinyls on the thing when it is easier to sell it if he really doesn't like the thing.

Sounds more like advertisement for the heck of it.