My 5.3 has 70k miles but like a couple of trucks I've heard in here in Florida it's got a knock at idle. 40psi of oil at idle and she runs great but it worries me because I've got big plans. Just curious if its more common or if I need to start building a back-up and leave this one alone. Already have K&N, custom exhaust, programmer, electric fans and throttle coolant bypass.

 

do you know how many degrees it's pulling?

 

It's not chattering, thats the valves, this is a knock in the bottom end... but it's just slight I have heard a couple of trucks doing the same but I still don't think it's right......and does anybody know The 03 and newer escalade esv 6.0 LQ9?

 

Ever since I bought the truck new i have had a problem with a rough idle/lope kinda thing. and when it does this it does occasionally make a knocking sound. Is this what you are talking about? It only does it ever so often though not all the time like a miss.

 

I bought my 02 Z71 new and it has had a slight knock from day one. I took it back to the dealer and they told me there was a service bulleton on it and the noise was from a particular type of ring they used in some years of the truck motors. I am not sure if that is true on not--never investigated it further.

 

I believe it's called "piston slap" for the noise you're hearing. My '00 Suburban 5.3 makes a slight knocking sound right after start-up for a few minutes, and fades away. After the oil splashes around in the cylinders and lubes up the pistons, and builds a little heat in the bores, is when the noise goes away. The piston skirt is "slapping" the cylinder walls when they're dry and cold. My mechanic buddy says it's common in alot of the LS-type motors because of the piston-to-cylinder clearance GM designed into the motors for less friction. He said it's not a problem, doesn't hurt anything, and I should just keep driving it, but not hard in those first few minutes after starting.

 

This is very normal with these motors at start up. Make sure not to use thicker oil or it makes it worse. There really isn't much you can do about it.

 

Thats why my 5.3 runs so good. Its got that heart beat of america going on. My slaps on cold starts until its warm, what you gonna do? Just rebuild it then.

rick