C6 Piston Slap

[Gary B.]

After I have taken my `06 C6 to My Dealership"s" (My favourite one had to closed when the GM S**t hit the fan a couple of years ago and to the second one that took over their franchise) I took it a Corvette Specialty Garage to have them to see if they could determine a ticking noise when the engine is cold. I only lasts about 10 minutes.

They determined is most likely is "Piston Slap".

The noise started about 3 year after I bought the Vette New.

The first dealership said they could not find anything. The Second dealership said "Yes we hear it but nothing to worry about.

My extended warrant is now over and the Corvette Specialty Garage tell me "To live with it, put in a New engine or sell the Vette.

No wonder the Dealerships and GM didn't want to address the problem.

Any one else have this problem with their engine? After looking into it further I find it is a fairly common problem.

Has any one had any luck with additives?

[Thomas H.]

Re: C6 Piston Slap

After I have taken my `06 C6 to My Dealership"s" (My favourite one had to closed when the GM S**t hit the fan a couple of years ago and to the second one that took over their franchise) I took it a Corvette Specialty Garage to have them to see if they could determine a ticking noise when the engine is cold. I only lasts about 10 minutes.

They determined is most likely is "Piston Slap".

The noise started about 3 year after I bought the Vette New.

The first dealership said they could not find anything. The Second dealership said "Yes we hear it but nothing to worry about.

My extended warrant is now over and the Corvette Specialty Garage tell me "To live with it, put in a New engine or sell the Vette.

No wonder the Dealerships and GM didn't want to address the problem.

Any one else have this problem with their engine? After looking into it further I find it is a fairly common problem.

Has any one had any luck with additives?

My C6 has some piston slap when cold also. It goes away as the car warms up. Some audible slap normal (don't know how "bad" yours is), just let it warm up before jumping on it.

I don't know if additives will help as it is caused when the pistons rock in the cylinders when cold, as they warm up and expand in diameter, the rocking is minimized and the noise goes away.

Tom

[John D.]

Re: C6 Piston Slap

Gary

There's no particular bulletin on piston slap for 06 models that I could see. FWIW here's what the serivce manual has to say.

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Incorrect oil filter without anti-drainback feature Install the correct oil filter. Incorrect oil viscosity 1. Drain the oil. 2. Install the correct viscosity oil. High valve lifter leak down rate Replace the lifters, as required. Worn crankshaft thrust bearing 1. Check the crankshaft end play. 2. Inspect the thrust bearing and crankshaft. 3. Repair or replace, as required. Damaged or faulty oil filter bypass valve 1. Inspect the oil filter bypass valve for proper operation. 2. Repair or replace, as required.

[Duke W.]

Re: C6 Piston Slap

It's been an issue over the years on many LS-engines, both aluminum block Corvette versions and iron block truck versions. It was a particular problem on the early LS6 engine. GM has taken several actions like tightening piston clearance tolerance and applying a polymer coating to piston skirts. Slightly "loose" pistons reduce friction and help to achieve good CAFE numbers.

Try to live with it. My Cosworth Vega and '91 MR2 both have noticeable slap when cold. It probably won't do any damage, but use light throttle and a little higher shift revs to avoid it, if possible, until the engine warms up enough for it to go away.

Duke

[Dick W.]

Re: C6 Piston Slap

Ya'll never owned a big block with forged pistons I guess. They defined the term "piston slap"

[Jim D.]

Re: C6 Piston Slap

Ya'll never owned a big block with forged pistons I guess. They defined the term "piston slap"

A 1970 LT-1 was just as bad.

[Duke W.]

Re: C6 Piston Slap

All the vintage SHP/FI engines from '62-up had forged pistons at about three thou cold clearance. The cast pistons were fit at about one thou. I think some of the modern LS aluminum block engine hypereutectic pistons fit at literally zero clearance.

Duke

[Ken R.]

Re: C6 Piston Slap

My 09 has it, esp heard it in SD with 56 temperature in the mornings. My Texas car wasn't use to that chill in the air.

[Clem Z.]

Re: C6 Piston Slap

interesting as i have had 5 new corvettes with LS engines but i have not heard this. maybe my 78 year old ears ain't what they used to be.

[Gary B.]

Re: C6 Piston Slap

Thanks for your replys. My "Piston Slap" started at about 2009. 3 years after I bought the Vette.

[Dick W.]

Re: C6 Piston Slap

A 1970 LT-1 was just as bad.

I had forgotten about them Jim, I used the LT-1 as a "pony" motor to start my big blocks