6.2L Lifter issue - ?

[xycrazy]

Do you have any reason to suspect the premium gasoline you put in?
Do you have any reason to suspect the gas station?

Unless you genuinely suspect the gas in the tank AND the station that you got that gas from,
(delete this post and) forget this line of thought, it makes no sense and can't help you or your truck.

I just said what I did not that either of those things have caused the issue. Was wondering why the car was shaking and thought maybe car runs now better on the premium gas (which in fact it did)

 

[Marky Dissod]

Point is, if the premium gas was a problem, it would be specific to THAT fill-up, and THAT gas station.

Since premium made it run better, it already has some carbon buildup somewhere.
However that is likely completely separate from the critical issue.

 

[Doubeleive]

I just said what I did not that either of those things have caused the issue. Was wondering why the car was shaking and thought maybe car runs now better on the premium gas (which in fact it did)

so it is pure speculation that it's the lifters? you have a cel on why not just scan it and see what the code is.
a small code reader from harbor frieght cost like $35, hell you could get the code from onstar for even less if not for free

 

[Tahoe14]

See if Carmax has another one in their system across the country and have them ship it in if you can work a trade out with them as a replacement. I would think they would want to keep you happy but who knows with these Dealers now days. Good luck, hope it all works out. I would do as suggested and scan the code. Maybe the battery is weak, these newer vehicles hate low voltage batteries and exhibit all kinds of weird issues.

 

[RST Dana]

Dealer for this for sure. Carmax are solely sales based. Not known for reputable repairs.

 

[tom3]

I'd first read that Carmax warranty contract. See what they specify and if their warranty only kicks in when no factory or other warranty is in effect. I wouldn't attempt to speculate on what is causing the problem. "It won't start and run, battery seems fine."

 

[B-train]

The push to start won't let the vehicle start if the battery voltage is below 12v I think. So, if the battery is at 11.5, all the interior stuff will work, but the starter won't engage when commanded.

You also need more info to go on. Do as suggested and get the code read with a cheap OBD2 scanner. Get a multimeter and check the battery voltage as it sits now. If it's below 12v, try charging it, or jump starting it with another vehicle.

The shaking on startup could have been a sticky lifter, or it could have been some carbon buildup that broke off and held one of the valves partially open until it was crumbled up and digested.

More homework needs to be done vs getting out the jump to conclusions mat....

 

[JGinLA]

Rodents ate into my wiring and wrecked the insulation under the hood. Are you near woods?

 

[Redracechris36]

I just had the dealer I bought my 2019 Cadillac Escalade from replace ALL of the lifters under warranty. Not just the bad one or the left bank. They went with an aftermarket lifter that they have had much better success with. When my lifter went, the truck started fine, it just had an awful tick. Very loud.