Why J?

I have been trying to get a little help with this but haven't been able to get any help.

I have a 2004 5.3L LM7 with 91,000 miles.

I parked the truck late last fall before it got cold and never heard a noise. Recently I moved the truck and decided to take it around the block to get things warmed up. The temp was in the 40's, I noticed that between 2000 and 2200 RPM I could hear a knock from the motor. Which went away after a few minutes after the truck warmed up. I was able to repeat this over a few days with the same result. After it warms up I can rev the motor to 4000 rpm and it is quiet. When it does make the noise it only knocks between those RPM's when cold.

This is my first year with this truck so I do not know if it generally does this when it is cold. Do you think this is the normal cylinder slap or something more? Steps I can take to diagnosis?

Thanks.

Stoner_Banks

I know for a fact that "piston slap" which is a nickname for when the pistons scrape the walls when moving (the walls condense a little due to being low temp and being aluminum) I have piston slap myself, not too bad/big of a deal (just warm up your car before driving).

1999 CAMARO
lsx
H/C/I
LS6 CRANK
HARDENED PUSHRODS & ROCKER ARMS
PORTED TB
PORTED INTAKE
LT'S
X-PIPE W/ BULLET MUFFLERS DUMPED

Why J?

My piston slap seems to be at 2000-2200 rpm when cold no noise at all at idle. No noise at all above that rpm.

Is this normal as well?

ThatOneKid

Based on what I know/have read, it's no big deal. Just let it heat up before you drive it.

Why J?

Roger that.

Guess I will worry about it if it makes the noise after warmed up.

flattusmaximus78

iTrader: (1)

My camaro and s10 both do it only cold, but they do it at idle and all rpms until the temp gauge budges. Thousands of miles on both.

rabbit320

iTrader: (11)

ive been researching this on many other truck forums (2000 silvy with 5.3, 190k) and the piston slap is normal, was declared so by a GM tsb report. so no worries

Why J?

I understand that the cylinder slap in this engine family is "normal". What I am concerned with is if what. i am hearing is cylinder slap.

My understanding is that cylinder slap is at idle on a cold start up and it goes away as the motor warms up. My noise is not present at start up, it only makes noise at 2000-2200 Rpms and then goes away after warm.

I would think a rod knock or spun bearing would get louder as the motor warmed up.