Piston Slap?? Can anyone describe

[Ramblin Fever]

what it sounds like?

Basically what's the difference between lifter noise and piston slapping?

[amigo-2k]

piston slap usually occurs when driving up hill and accelerating (at least for me). And it sound like rocks being shacken around in a tin can.

[Ramblin Fever]

Ok, I have had this sound when climbing a hill, but not all the time. Does your Amigo do the same thing?

[Ramblin Fever]

FWIW though, I was just reading on another forum that if you have a piston slapping during idle, the sound will get lighter as you put it into gear??

My "tapping" wrapping sound does get somewhat softer, very slightly by putting truck into gear.

Any thoughts?

[amigo-2k]

Not so much any more since I started using Chevron Techron before every oil change (starting at 15k) and I also think my sea foam before oil changes has helped it too. I have about 65k right now.

[rodeo02]

Originally Posted by Ramblin Fever

what it sounds like?

Basically what's the difference between lifter noise and piston slapping?

It's kind of a rattley, rod-knock kind of noise. More from inside the engine than from the top-end. Happens at startup and idle. My 1998 chev 4.3L did it like crazy. It's mostly a GM issue, but plagues others too. They design their pistons so short that they can rock slightly within the confines of the cylinder, causing the knock noise. Short, almost skirtless pistons are common place today as manufacturers make more lightweight, efficient engines. Supposedly it's harmless, just annoying.
G/luck
Joel