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In 2020 I purchased a new Silverado 2500HD.   Vehicle has the GAS 6.6L Engine.   It recently had it's second Oil Change and Service.   Vehicle ONLY has 6,500 miles on it.   Now it has a knocking noise when idling.  I took it back tot he dealer where I purchased it.  They have had it for over a week.  Initially told they had no idea what the noise was.  They were communicating directly with GM to diagnose the issue.  As of now they have replaced engine bearings and dropped the Oil Pan with no loose or metal particles in the Oil.

With all of that said and done the noise is still present and they are waiting for further instructions from GM.

Just curious if anyone else has had this issue?


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  • 5 months later...

I have the same truck with less than 5,000 miles and haven't noticed a knocking. I also made sure to use full synthetic when I did the oil change. While it may not seem like that should matter on an engine with such low miles, I had a Hemi previously and the only way to keep it from doing the infamous 'Hemi tick' was to use full synthetic. Completely different motor, I know, but still worth a shot. If you didn't do the oil change yourself, don't assume they used full synthetic either even though Chevy specifically calls for it. 

2020 was the first year for that motor so it is possible it has it's own version of the 'Hemi tick'. 

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  • 4 weeks later...

Hate to bring this back from the dead. Specially being my first post. But i recently changed my oil using OEM filter and quality oil. I changed mine at 3k miles its a 2021 6.6 gas custom. And now i have a slight knock random only in park and neutral. Oil pressure is about 38 to 40 psi hot idle. I used a stethoscope on my heads and everything sounds good. I am baffled sitting there with the door open you can here a random knock or clank similar to  a lifter but not like a AFM  collapsed  lifter on a half ton.  Set parking brake in drive no noise return to park or neutral and i will have a random tap/knock sound.


Dunno has me stumped went out and floored it oil pressure goes up as should no crazy sounds. no missing at idle or stumble. noise is not associated with rpm.   Kinda crazy sold my 1500 at 39k after AFM lifter repair after dealer had my truck for a month.  


If any body ever has a chance to listen to there truck in park after a drive right around the bell housing and oil pan location for a faint but audible knock/clank sound please chime in. 

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It was reading about the 6.2 having a second batch of bad lifters and valve springs.  Some of the 6.6 were affected the first time around. Take it to the dealer for a check. They should be able to detect misfires that you wouldn't be able to on your own.

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Yes i have read that as well. Along with something about a fuel line with a check valve in it making a noise. And for it to be replaced. mine was built in June 2021. but still could have a valve train issue. Anyways if i take it in i will report back in what they find. In case this becomes a 6.6 issue 


One thing i am  sure of its certainly not like my 1500s collapsed  afm lifter or any broken valve spring noise. That can be found on the youtube. Not much info out there on these motors yet in the way of issues. 

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