2021 Tahoe engine noise - knocking sound

[RST Dana]

My first guess would be some piston slap, used to be pretty common in the LS motors. But those engines today are pretty well sorted out for that condition I think. Give it time, if it's a serious issue it'll get worse.

Or sooner if the OP try’s WOT a few times. Once it finishes shredding metal, the dealership can sort it out.

 

[Doubeleive]

Or sooner if the OP try’s WOT a few times. Once it finishes shredding metal, the dealership can sort it out.

lol, sounds like something i would do, I knew there was a reason they rev limit it to 3k in park

 

[tom3]

Listened with some earbuds, does sound like something external. Rotating and hitting some heavy sheetmetal. Have to crawl under it to zero in on the noise when it's doing this. Can't believe a brand new vehicle would do this unless you've run over something pretty substantial and done some damage. Keep us posted, interesting.

 

[Quark]

Incompetence abounds at dealerships. No one should have to crawl under an $80,000 vehicle that is new and under warranty but that is the state of our country and the retail market. Viva la China baby.

 

[peyc2]

sounds like the dreaded lifter failure. which i had. but it didn't go away. they know this engine has had problem with lifters.

 

[robhotdog]

Hello,
My 2021 Tahoe SRT 5.3L started making this knocking or clanking sound in the engine (video below), mostly does it on cold starts for 1 minute, then it somewhat goes away, you can sometimes hear a random clank while driving, car almost stutters a little when it does. At some points I can feel the car shaking a bit as if it has a mild cam.

Took it to dealership but they couldn't replicate it, said to look for patterns or ways to replicate it. Does anyone know what this might be or had similar problem?

Show that video to dealer!! It's good you have documentation from previous attempt. They must cold start it sounds like. Sounds like you have a serious oiling problem with likely camshaft failing!! Go to a large dealer for the best techs. If that doesn't work call your gm customer help line in the back of your owners manual. They Will Help You! Do it NOW!

 

[robhotdog]

One last thought..would liked to hear you say the date and time of day. Also include showing vehicle and vin # on same video to eliminate any possible arguments. AFM failure I suspect. Use your warranty! You paid for it.

 

[EddieC]

I have had many vehicles including motorbikes with piston slap and that's not it.
It does sound like our subaru when the air conditioner compressor clutch turns on and off, and it does it several times like that sound you have. Might be worth a listen. If it is, maybe it's something odd going on with the climate control locking the clutch which could be weather or temperature related; maybe a variable why you heard it but they didn't.

 

[DangIt]

Hello,
My 2021 Tahoe SRT 5.3L started making this knocking or clanking sound in the engine (video below), mostly does it on cold starts for 1 minute, then it somewhat goes away, you can sometimes hear a random clank while driving, car almost stutters a little when it does. At some points I can feel the car shaking a bit as if it has a mild cam.

Took it to dealership but they couldn't replicate it, said to look for patterns or ways to replicate it. Does anyone know what this might be or had similar problem?

That is 100% the issue with faulty lifters and pushrods that I dealt with on my 2021 Tahoe Premier last summer. It seemed to be a cold start issue at first. I took it in and was told the same thing, despite having an almost identical video. I suspect they knew what it was but were hedging to keep the repair techs from being overwhelmed (and to buy time to get more backordered parts in). I drove it another 1000 miles before they acknowledged the issue was the lifters. By that point, it was making noises all the time and throwing codes. Many manufactured within a certain 3-month range had this issue. Chevrolet tore down the engine and replaced both banks of faulty lifters. I have not trusted the vehicle since.

Search my other posts to find my video and write ups about it. I would not drive it far from home, as you may get stranded. You should be able to take it in now with all the other videos and posts about this. It is a well known issue that I cannot believe they are still pretending they can’t identify right away.

Open a case with GM. They have links to lemon law and warranty teams on their website. Follow your state’s requirements and send them a certified final repair letter at the appropriate point. Mine was out of service for 20 business days in the same year, so it met the statutory definition of lemon in NC. Since I don’t trust mine anymore, GM just recently agreed to replace it.

I’m sorry you are having this issue, as I’ve been there. Part availability has improved, so you might not have quite the delays in repairs that I did. As to whether you trust your Tahoe again, I certainly couldn’t. But I certainly wouldn’t drive it much in that condition if you are planning to keep it after the warranty repairs have been done.

 

[thingraylinetah]

stuck lifter. It's a common problem. Even on the newer ones. I've seen people with 10 k miles on the vehicle have to have lifters replaced.