6.2L AT4 cold start clunking/knocking noise

Rao318 · Dec 15, 2022

Hey everyone,
Has anyone experienced this noise? Have had the truck over 2 years and never had this issue. Only happens when it's been sitting in the cold for a while. Sound last a few minutes and when truck warms up it stops. GM gave me the run around saying they would have to put my intake back to stock to dig further(S&B CAI). Can't seem to find any posts anywhere with the same sound. Truck seems to be fine when it warms up, no codes but it doesn't sound good at all. I attached the YouTube link below.

Thanks!

Mike

Pb82 Ronin · Dec 16, 2022

Subbing...curious WTH that is.

Rao318 · Dec 22, 2022

Pb82 Ronin said:
Subbing...curious WTH that is.

Lifters apparently. The worst case he has heard haha ugh. All covered under warranty but no truck for a month! Couldn't find that sound anywhere online. Goes away when warmed up so didn't think Lifters.

Blade's AT4 · Dec 23, 2022

I've not heard it personally on mine, but it sounds like something trying to engage/initiate and might be frozen? What part of the engine bay is it coming from, if you can tell?

Rao318 · Dec 23, 2022

Blade's AT4 said:
I've not heard it personally on mine, but it sounds like something trying to engage/initiate and might be frozen? What part of the engine bay is it coming from, if you can tell?

Gm is saying its lifters! So it's there to get lifters replaced. Yea I didn't think lifters as the sound goes away as it warms up. Sounds like something isnt fully engaging causing engine to hesitate. I will follow up when they take it all apart as he's going to update me on the way. I swear it this DFM, you know when the dealer is telling you to buy a pulsar to disengage the DFM/AFM that it's a problem.

Duramaximus · Dec 24, 2022

That is odd. Any update on this?

Rao318 · Dec 25, 2022

Gm is saying its lifters! So it's there to get lifters replaced. Yea I didn't think lifters as the sound goes away as it warms up. Sounds like something isnt fully engaging causing engine to hesitate. I will follow up when they take it all apart as he's going to update me on the way. I swear it this DFM, you know when the dealer is telling you to buy a pulsar to disengage the DFM/AFM that it's a problem.