Slapping Pistons...

[The Laplander]

I have already a little slapping i my engine ( only 14000 Miles ) and i´m a little worried that it will be worse...
I have read on some other sites that it is a problem that will only get worse and louder, and in some cases wear my engine down.
My slapping starts after 15-30 sec. and goes away after 3-5 min.
I have a 1999 Coupe´.
That made my worried, do anybody know if this kind of slapping will be worse or stay as it is?
C4C5specialist?

[danl72]

A little slapping is normal. Does it get louder as the car gets warmer. You should get a definative answer shortly. Welcome to CAC.

[c4c5specialist]

Hi there,
From what you have said here, I would suggest it is normal.
Most c5 engines, with tolerancing within specs, will show some cold start knock.
This is due to the carbon buildup on the ring land, causing a slight rocking of the piston, thereby the knock.
Now, the reason that it goes away, is that the piston expands as it gets warm, and stops rocking.
I would not worry, however, if Dan is correct, and it gets worse as it warms, then I would worry.
Besttoyou, c4c5

[The Laplander]

Thank you for your answers!
I first thought that it was something serious, but now after everything i´ve read about this slapping problem it feels better...
I am glad that the "slapping" disappears completly when it´s warm.

You, c4c5specialist mensioned something about carbonbuildup..?!
I have heard about carbonbuildup on older cars with high mileage, but is it also possible that it occurs already after 14000 Miles?

In that case, can you please recommend any good chemical for de-carbonisation?

Thanks!

J.

[c4c5specialist]

Hi there,
Yes, the GM part number here in the states is 1050002, and it is called TOP ENGINE CLEANER. This is what we use to decarbon cylinders and engines. Your local Corvette specialist should be able to correctly advise you, or serve you to do the decarbonization procedure. This is basically removing all 8 spark plugs, and adding about 4 ounces of fluid, to each cylinder, and letting it soak over night.
It is very time consuming, and it takes the chemical sitting over night, to break up the carbon.
If you would like further information, please let me know, besttoyou, c4c5

[poorboys831]

hi c4c5specialist,in regard to the de-carboning proceedure-would that be an advisable proceedure from a maintenance standpoint?my '99 is running fine-i know the old addage "if it ain't broke don't fix it "but i like preventive stuff-i just turned35k miles-thanks

[c4c5specialist]

Hithere,
Sure, the decarb is always a good maintenance idea.
Just remember, alot of emissions failures for oxides of nitrogen, are usually caused by carbon buildup in c5.
I would definately suggest this, however, some view it as simply a dealership attempting to sell things.
I would consult your local dealership, to see if they will perform the procedure.
Besttoyou, c4c5