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It appears my Camaro has a nasty case of "piston slap". If my understanding is correct, GM tried to cut costs by not matching pistons and blocks together perfectly. The result is a piston that is a little smaller than the cylinder. The cylinder bangs around a little bit, and eventually the sides begin to wear. This is pretty common in LS1s and many other GM engines and usually goes away once the engine is warm and the pistons/block has expanded. Usually it's not that bad and not really doing much harm to the engine, so GM denied most claims of cars under-warranty.

I have an extended warranty, and a case of slap that doesn't go away after the engine is warm. The dealer is in talks with GMPP or whatever GM's warranty company is, and they're trying to figure out how they're going to approach this. So, what are you guys betting? Think they'll try the cheapest fix no matter how unlikely it will work? Think they'll actually pull the motor, replace what needs to be replaced (I'm guessing a piston)? Think they'll just give me a new engine (I thought it was unlikely, but a mechanic said it could easily happen, and Chrysler did just this in their cars that had piston slap), or do you thing they'll give me the run-around seeing that my warranty is up next year?

posted by  giant016

UPDATE:

My dealership let me know that GM could deny my claim since I have no proof that I changed the oil (didn't keep Autozone recipts), and it clearly states in my warranty handbook that they can deny me for that. Luckily somebody was on my side, because GM is buying and installing a new long block next week. I'm seeing how much the old block will cost me, if they will even let me buy it back. It would need to be bored out as the cylinder walls are scratched, and I'm guessing new pistons. To be honest I just want to take it apart to maybe learn a thing or two, and if it's cheap enough I could probably part it out and come close to breaking even.

posted by  giant016

I've heard of a guy on tech who put good street tires (not even DRs) on his GTO and then his rear started whining, he went in to have it fixed and they completely voided his whole warranty at every GM dealership worldwide, over a set of completely legal full depth street tires.

Screw GM, they'll probably screw you.'

Sure its piston slap and not valvetrain noise?
What oil do you run?

posted by  Enthusiast

They took apart the engine and the piston skirts and cylinder walls were pretty messed up. One of the cylinders/pistons had was something like 6/1000 over spec, and the tech at the dealership said that was way too much.

I run Mobile 1 5-W30. The consensus is that M1 isn't bad, and it's readily availible.

They couldn've totally voided my warranty since I had no proof of an oil change, but an inspector for GM came out and ok'd the work, so I'm :mrgreen:.

posted by  giant016

DAMN youve got a good dealership stick with them.

they replacing the shortblock or what.

posted by  Enthusiast

We bring all of our cars there, and even bought one from them.

Getting a whole new longblock.

posted by  giant016

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