Si, with the heads off the pistons in my 5.3 when at top seem to have a lot of play. I understand piston slap now. My question is when there is wear is it generally mornonnyhe piston, the cylinder or pretty evenly between the two. If the bore is rated at 3.780 are they generally accurate to that from the factory?

 

Of course I can't say whether your particular motor has enough play to present a problem, but audible piston slap has not generally been correlated with excessive wear on either the cylinder liners or pistons upon tear down.

 

Huh? I've torn down quite a few where piston slap was getting louder over time and pistons skirts were worn and bore was out of spec, No serious wear on crank/cam/rod bearings. Bore and new pistons and good to go.

 

The only way to know for sure is to measure, Generally if you're going to take it down that far then a full rebuild is a no brainer.

 

 

Wow, yes, that's certainly a crazy amount of rocking right there! And per above, it makes sense that if piston slap has gotten louder over time and continues to slap when the engine is fully warmed up, there would be evidence of wear.

My car has been a piston slapper when cold since I bought it 15 years ago at 33k. It has 167k now and the slap is no worse now than it was then. That's why I said "generally correlated." In other words, the mere presence of some piston slap is not an absolute indicator that excessive piston or liner wear is taking place.

Piston slap was controversial when the LS engines were new and some owners were clamoring for warranty replacement engines because of cold slapping. But inspection was not generally showing abnormal wear on such (admittedly relatively fresh) liners and pistons.