Chev 4.8 engine

[gmaj]

2010 Silverado 1500 LS 4.8 engine. Km 83000
noise from engine. Ticking noise, chu chu chu noise, dealer told me lifter problem.
tried Rislone, ACDelco engine oil supplement. Still noise
Removed valve cover. Turned crankshaft, push rods are pushing rockers, valve springs. Then started, push rods rockers , valve springs move.
I hear chu chu chu, hissing noise. Smoke from right exhaust, I think due to oil when I start with valve covers off. I am going to clean & try.
any advice, where to check now. Only km 83000 only.
thanks

 

[gmaj]

Typo
Should be any
Not many

 

[TollKeeper]

The only way to properly diagnose that one is with a compression test, and a leak down test.

I am thinking either you have a stuck valve, pent valve rod, or a stuck rocker.