2021 Tahoe engine noise - knocking sound

[Lruelas]

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?

 

[R32driver]

If that was my rig I would not drive it anywhere but straight to the dealer and not touch it again til it's fixed. That sounds terrible

 

[Doubeleive]

so, you took it to the dealer and left it overnight so the tech could cold start it in the morning and it didn't do it?

 

[Lruelas]

so, you took it to the dealer and left it overnight so the tech could cold start it in the morning and it didn't do it?

That's right, they claim to have driven it 20 miles and tried cold starting it two different times. They did nothing for me and told me to look for patterns or look for a way to recreate it. It does it nearly every cold start in some way or another, it's a bit inconsistent I will say.

 

[Stbentoak]

I'd take it back and tell them you will be there the next morning to start it with them. Don't touch it till you can go out and start it with a Tech in the passenger seat...

 

[Micahsd]

That’s a terrible noise. Wonder if it’s a lifter sticking…just went through the lifter issue on mine as when I went to start it up after sitting for a bit is when it went bad.

Course in my case it would miss and didn’t have the loud noise although they had to replace a valve along with the left bank of lifters.

 

[B520044]

That's awful. The video alone should be enough evidence for them. Take it back soon or to a different dealer. Do you know your build date? Would be interesting to see if yours is in the bad lifter time frame.

 

[Doubeleive]

take it back like mentioned above and make them aware you will be contacting gm customer service as well, just go to the gm website to do that, whoever you chat with point them to your video also.

 

[tom3]

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.

 

[Geotrash]

Sounds to me like the noise is at the same frequency as crankshaft rotation. If it were cam related, it would be at half crankshaft rotation. I would look for a loose crank pulley, or perhaps something at the rear of the engine like the flex plate. Either way, it definitely ain't right.