Looks like I have the old 5.3 smoke on start up.
Just started a couple of days ago. Not every time but only when cold.
I'm going to try cleaning the valve cover first. Any tips on modifying the drain on the valve cover or is the Dorman impoved
replacement the way to go?

 

My wife demanded selling our 05 Sub when this happened. Didn't like the ghetto car look. By the time we traded it was eating a qt every 700 miles

 

Always be aware that could be valve guides and seals that need replaced. Get the less expensive updated valve cover though to try and correct.

 

Pretty sure it's the pcv valve cover issue and not valve seals or guides. 150K on the motor with no other smoking.
Only does it on cold start up for the first couple of seconds then clears up.
Just started with no warning. Classic symptoms. The is a TSB for this issue I believe.
Parked the Burb nose down on our slightly inclined driveway and didn't have the large puff this morning.
Will do this test a couple of times before pulling the valve cover.
Might try some Seafoam in the crankcase. Can't hurt to clean it since it's due for an oil change anyway.

 

classic symptoms of worn valve guides. do the spark plugs have ash deposits?

gm modified the valve cover for the next gen not a 2006

if you have xs pcv flow; oil would blow back into the resonator box on the air intake tube.

are you burning oil.

 

Here is a perfect example of my sudden issue.

 

that's more than a puff of smoke at start up
secondly... different 5.3L engine than what you have

 

Ok....so 2006 5.3 isn't affected....smh...

https://extremediy.org/2006-silverad...tartup-solved/

everyone is so quick to jump to guide seals. No smoke on heavy acceleration or deceleration. Both times would suck oil past the valve seals.

 

Not jumping on any bandwagon, first, you got it fixed, and responded to you post. That helps alot. Second, posting valve seals is a recommendation, and one I would have suggested. Dealing with engine issues are that when you are not there, but your vidio is what helps people to understand the poroblem.

 

Typically, when the guides and seals start to go, the first sign is the smoke at the cold start and then gets worse and you see smoke when accel, like passing someone. I brought it up to cover all bases. Plus, in the same post I said to try the updated valve cover. My recommendations are just that, a recommendation because someone asked for help. If other recommendations bother you when they don't go with your thoughts, click past them or make sure to say in your help post that you don't want to hear this or that and then I can keep my BIG MOUTH SHUT.