2021 tahoe 5.3 and p0308 code

[West1]

I purchased my Tahoe in October of 2020 and besides the few recalls I had to take it I for, I had no complaints. As time went on, I still had no complaints but worry started to grow as the stories of the 6.0 started to grow, eventually the 5.3 afm talk started.

5yrs and 84k miles later, I was accelerating from a stop sign, heard a pop and loss of power. I pulled over and plugged in my code reader and read the p0308 & a drivetrain code.

Had it towed to my local trusted mechanic to schedule a diagnostic and compression test.
He mentioned without opening up the heads, he can’t give a definitive answer and mentioned when the engine turns on, it runs fine and once it starts to warm, valve #8 takes a dump. He doubts it’s a sensor and believes there’s an exhaust leak. He also said this year alone, he has replaced lifters on 4 5.3 engines this year and said mine seems different but can’t verify till the heads are opened up.

My question as I am no mechanic, what are the possible worst case scenarios with a ballpark price?
Would a bypass chip save new lifters if the lifters are the issue?
Link to part I was going to purchase a week ago https://a.co/d/0gEcIKBN

I’m torn between trading it in or attempting to repair. I really enjoy my truck and have no interest in getting a new or used vehicle but realistically don’t want throw a bunch of money into something that will just happen again.

Thanks for any advice, tips or suggestions.

 

[West1]

Here is some screenshots of my report.
Does any of this point to something kinda specific? It’s like reading in Russian to me, I don’t understand it.

 

[jfoj]

Before you have cylinder heads pulled, I would have the mechanic pull a valve cover and inspect the cylinder #8 spark plug first, then possibly use a more advanced borescope to look inside the cylinder at the valves. Possibly perform a compression test and cylinder leakage test on the #8 cylinder.

A decent borescope can also go a long way to fully understanding what is going on by looking down at the cam and lifters as well as looking inside the cylinder(s). A decent borescope with with a thumb control to rotate and bend the camera around will allow the mechanic to look back up at the valves to make sure there is not a burner or chipped valve edge.

Something like this - https://www.amazon.com/Articulating-Detachable-Inspection-Semi-Rigid-Automotive/dp/B0G239JCXJ?th=1

Depending on what is found on the first inspection by removing the spark plug, the valve cover may need to be removed to inspect for bent pushrods, damaged rocker arms, and valve springs and make sure the #8 cylinder valves open all the way.

Unfortunately if the problem is with a lifter(s), a cylinder head does need to come off, if the cam is damage, both heads and the front of the engine need to come off which raises the cost and complexity.

 

[Joseph Garcia]

^^^^^x2^^^^^

 

[blanchard7684]

Pull #8 plug, inspect.
Do compression test.

Go from there.