Piston Slap

[fleetwoodguy79]

I am starting to hear the so called "piston slap" from the front of my GP now that it has gotten to winter. Car runs fine when it gets up to temp! Is this an issue that I can fix? Is it gonna do some damage to my engine if I keep running it like it is? Thanks in advance all!!!

[GnatGoSplat]

Only way to fix piston slap is with new pistons.

GM claims piston slap does no damage, but in reality it can cause some scoring of the cylinder walls as the slapping sound is the piston tilting and its skirt slapping on the cylinder wall.

[GrandPrix34]

wat exactly is this piston slap? how do you know wat it is? when i drive to about 3000rpms and let go of the accelerator, i hear this clunk or some sound like that, is this it?

[GnatGoSplat]

Piston slap sounds like a rattling/tapping/knocking type sound.

It's usually quite audible.

I don't think a single clunk when you let off the accelerator is piston slap. Piston slap is caused by piston tolerances being poor, so the piston is able to tilt allowing its skirt to tap on the side of the cylinder walls.

[fleetwoodguy79]

So why does this go away when the engine warms up?? As soon as the temp starts to rise it almost immediently goes away. So it looks like i'll be replacing my pistons??????

[AWeb80]

I'm guessing the reason the piston slap goes away is because as the engine warms up, the metal expands and the tolerances become tighter. Just thinking logically.

[GnatGoSplat]

aweb80 is exactly right.

 

You could replace your pistons, but GM has always maintained that piston slap is harmless and nothing but an annoyance. Many people disagree, but personally I'd drive it till it quits!