what is it and if i have it how do i get rid of and prevent it?

 

"carbon knock" is caused by hot carbon deposits in the cylinder. The hot carbon deposit works like a spark plug causing pre-ignition or dieseling effect when you shut it off.. Its fairly common on older cars with carbs and point type ignition but it a rare thing on modern vehicles. If your getting that kinda carbon build up something is WRONG.

 

just thought id ask because in my other post about piston slapping gonzo said it was possible. oh well, guess i'll continue to try and figure out what is knocking in the engine

 

In that case he is probablly refering to a carbon build up on the rings between the piston and cylinder wall. These usually dont cause the 'hot spots' GV was refering to but could cause a knock from the decreased piston to wall clearance.

 

SeaFoam top engine cleaner will help clean all this up.. Or you can buy a supercharger and add water injection. LOL

 

Where can you get seafoam from??? autozone?? or at the dealersihp...

Is this something you should do for matinence reasons???

 

Or you can buy a STS and drive in the rain...

 

Nah, that would be more catastrophic. Kinda like the difference between a campfire and the Toba Eruption.

I know you used to be able to buy it at the dealer. I'm not sure where people are buying the stuff now.

 

napa sells it

good stuff

 

Piston slap is the rocking noise of the piston against the cylinder walls do to loose piston clearences,this noise goes away with heat expansion of the piston with normal engine warm up.You can have carbon build up on top the piston and cause a knocking sound similiar to a bearing failure or oil clearence issue.If your engine see's a lot of short runs were engine temps dont alway come up for any length of time and not running the engine hard or long trips,these are a couple of factors which can contribute to carbon build up.