slipryvette

On may 2010 I purchased a 2008 vette, with no noise, after 2500 miles I brought it back to the dealer for oil change. After I drove off I noticed a drop in the oil pressure , then the load cold start piston slap.I returned to the dealer and I was told all was well and it was a normal noise.Has anyone been successful in getting a dealer to remedy the problem? HELP !

boraxman

So it started after the dealer did an oil change? Maybe he used the wrong oil?

slipryvette

I have put 10K miles since [with proper oil change at dealers]. I wrote them a letter telling them I believed the engine had treament in it to keep it quit. Cheap trick to sell one. 3 seperate dealers tell me this is common.I researched the LS3 engine about this and was blown away! I need to see if anyone was successful in makeing Chevy replace an engine thats out of clearance?

lastcowboy

they put 50wt.oil in them at the factory so its nice and quite....

VET4LES

GM has had a piston slap problem for a long time. I had a 454 motorhome with it and GM said it was normal. I drove it 65,000 miles, gave it to me daughter's family they put another 20,000 on it and sold it. It ran great the entire time. My 2005 C6 has started piston slap and I'm not happy with it but I know what GM will say if I complain. It goes away when the oil is warm.

cwing85b

My local dealer said piston slap is "normal" on the LS3. Their experience has shown that it is "extremely important" on a cold start that the engine be allowed to warm up a few minutes before driving. They told me that when people start them, throw em in gear and take off, they usually end up with piston slap. They also said although it is irritating, it is not a concern unless it gets really bad. I have no issues but I have sure seen a lot of LS3s in their shop for this very reason.

cthusker

Obviously GM recognizes "piston slap" as normal occurrence to some extent. I say that because in your GM tune there are adjustments that can be made to the table called... "Piston Slap". It's a table that's used to modify spark advance in order to minimize "piston slap" during warm up!

Mike's LS3

Piston slap can be caused by a couple of issues. One is loose tolerances which will cause piston slap at cold start up and quiet down after the engine has reached normal temps. The second is carbon build up on the the piston ring land. Piston ring land are the two parallel surfaces of the ring groove which function as the sealing surface for the piston ring. I experienced the latter issue on my 08 corvette. GM service tech confirmed the piston slap and said he could do nothing at that time. I did some further research and used a product called BG44K power enhancer. It is designed to dissolve carbon build up in the combustion chambers, piston tops, piston ring lands etc. The treatment is added to your gas tank, I used 1 can to 12 gallons of gas. After the first treatment, about 80% of my piston slap had quiet down. After a second treatment, 100% of my piston slap was gone and continues to be quiet after 5k miles of driving. In my case, the piston slap was caused by carbon build up. Why? Possibility due to the aftermarket air intake with the oem tune running very rich at WOT? Since then, I returned to the stock LS3 air intake and all is well. BG44K power enhancer worked for my piston slap due to carbon build up, but will not work for loose tolerances. It might be worth a try!

VET4LES

Good information. I've read about this a few times and I'm going to give it a try. Where did you find it?

RT2SJB

I have an 07 with piston slap until the engine reaches 170 degrees during the winter months. During the summer even when the engine is cold I do not hear any piston slap. I also took it to two dealers and they said it was normal not to worry. I did use the BG 44k and that seemed to reduce the noise but did not totally do away with the noise. Now I just let it warm up before I take it out and it runs fine.

66biskwik

I have a 2003 Yukon that has had it since day 1. Got 175000 on it and still sounds the same when you first start it. I wouldn't worry about it unless it gets worse. I was told it was do to the cylinder walls not being perfectly round??. You think they would have figured it out by now.

Gearhead Jim

Seems like I read somewhere that the cylinder walls are not perfectly round when cold, so they will be perfectly round when warmed up.

Sounds logical, but I have no idea if it's true.

Our 2001 LS1 Corvette sounded like a diesel truck for the first few minutes after starting, winter or summer; almost quiet when fully warmed up.

Still running great and sounding the same when traded at 66k miles.

JoesC5

Cylinders are bored round and honed round(the ZR1 is honed with a torque plate to ensure it is round when the head is torqued. The non ZR1 engines are slighty distorted when the head is bolted on and even more when the engine is up to temp.

The pistons are machined out of round and they do indeed expand to a more rounded dimension when at running temp.

All GM engines(since 2001) have a synthetic coating applied to the piston skirts and are ever so slightly larger then the bore. That is to make the piston fit tight when cold, The first time the engine is fired, some of the coating is worn off and some is transferred to the cylinder walls. This is to reduce(eliminate?) cold piston slap and to keep the piston from rocking in the bores which helps the rings sealed. This helps cold start emmisons and cuts down the amount of complaints from car owners hearing the dreaded piston slap.

Mike's LS3

I purchased BG44k at an Acura dealership parts department. Look on BG44k's website to find a retailer. I could not find it in any auto parts store.