Having issues with my daily driver

[84_SS]

So I've been noticing some lifter noise from my daily driver lately. It's very repeatable, it doesn't do it in stop and go traffic or city driving, but if I drive on the highway with a sustained rpm of 2000 I will hear it after only a few minutes of driving. 2003 GMC Sierra with a modified 6L. I see no change in oil pressure, temp is good no lose of power I just can't hunt it down and want to be sure before tearing the heads off the truck. Could it be possible for a lifter to be collapsing even at a higher rpm?

 

[pontiacgp]

you're not the only one..

https://www.google.ca/search?source...litre valve noise&aqs=chrome..69i57.14293j0j8

 

[84_SS]

most of those guys are getting the standard LS piston slap on cold start. Everyone I've owner or been around has done that. The thing I'm describing is different, it happens after the engine has warmed up.

 

[pontiacgp]

but some of them have injector noise and roller lifter noise. My roller set up make more noise than a flat tappet set up and sounds like the back lash adjustment is out. Why not try some transmission fluid in the crankcase and run it for 1/2 hour before you change the oil.