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Discussion Starter · #1 ·
Just picked up my new 2500HD 6.6L gasser two weeks ago (after a five month build) and noticed what sounded like lifters rattling after a few days. Took it in today and sure enough they think it is the lifters and will confirm tomorrow. If so, two weeks min to get the parts and fours days rebuild. So disappointed. Anybody else hearing of this? (Sorry if this has been previously discussed, searched but could not find a post)
 

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That's the first I'm hearing about lifter issues on the 6.6 gas. The AFM motors have plenty of lifter issues, just like they always have.

Will be interesting to see if the lifters are in fact bad, and what the method of failure was. Definitely keep us updated.
 

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First for me too. I am curious, since this is your first post, if you really have a 6.6 or if this is some anti GM campaign.
 

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Discussion Starter · #4 ·
This is my second Silverado, wife on her second Tahoe and daughter drives an Equinox so we are a long time Chevy family. No anti-GM campaign but I could probably start one after todays news. I researched this truck forever and never saw anything about lifter issues so this comes as a complete surprise, hence the reason I'm asking the experts if this is a known issue or a fluke. The CS rep at the dealer was not 100% sure its lifters but said the engine guys will confirm tomorrow. I asked if this has been an issue and she said no but also said she now has three other vehicles diagnosed with the same problem. Not sure if they were also trucks but will find out tomorrow when I go in to get a temp vehicle. I will keep you posted
 

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I'm just going to get some beer and popcorn, kick back on my comfy couch and hitch a ride on this thread. Definitely interested in what the diagnosis is and what corrective action is required/taken.

Cheers!

Mike
 

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Could have just been a bad batch of parts or improper assembly. It is going to happen unfortunately.

Hope all goes well, this is the first I'm hearing of 6.6 problems.
 

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2015 Silverado LT Texas Edition
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Depending on the diagnosis, (If it is,in fact internal to the motor,) I would either:

Force them to replace the motor, or pick out another truck.

Screw "repairing" a two week old truck.
 

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Haha, the L8T is not an AFM engine and does not have DFM.

https://gmauthority.com/blog/gm/gm-engines/l8t/

Try higher octane gas, both of my L96 engines have had a little valve ping using 87 octane and will occasional ping when lugging.
Debate why all you want, I have checked the valvetrain twice on the 2013 its all to spec.
Higher octane gas prevents predetonation under compression, totally solves it (at least for the L96).

When you say "build", did you put on bigger tires without changing axle gears and/or reprogramming the trans for adjusted shift points?
If yes, you are probably lugging and just about every pushrod engine is going to ping when lugging.
 

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It shouldn't be octane ping. The 6.6 is a DI engine and the fuel is not injected until the bulk of the compression is done. The 6.0 is a port injected and the fuel is injected during the intake stroke.
 

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Discussion Starter · #11 ·
Here's the short version, we need a long bed so initially ordered a dbl cab with a San Diego dealer. They came back a month later and said they could not get the allocation. Then went to (what were told was the largest truck dealer in the US) Classic Chevy in Tx and they said they could order it no problem. One month into that process GM cancelled the order, no more dbl cabs in 2021. We revised order to a crew cab and it came in about three months later. Picked up in Dallas two weeks ago and drove back to Ca. Noticed the pinging the second day on the way back but we were 800 miles out so continued on to Ca. Made the app with my local dealer and yesterday got the news about the "suspected" lifter issue. Not lifted nor any oversized wheels were added, and I nursed it all the way home. Hoping for the best, would hate to start this process over with the difficulty getting trucks theses days.
 

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Trucks are rare....I believe this picture is Classic Chevy about a week ago....
 

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I'm still baffled that after 100 years of combustion engine fabrication, they still can't build a reliable motor in 2021...

It's almost scary to buy a brand new vehicle (every brand).
 

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Discussion Starter · #14 ·
Just talked to the dealer and its not the lifters, it's bearings in the steering shaft. Whew! She said there is actually a bulletin out on it. They will replace the shaft (currently on back order of course) but it is not a safety issue, just an annoyance and the truck can be driven until its replaced. When I initially dropped it off I told her it sounds like lifters but it did not feel like lifters as I had experienced in the past. It was somewhat intermittent when accelerating or going up hills so I thought it was a fan wobbling or something loose in the engine compartment.

Needless to say, I wish they would of diagnosed it before suggesting it was the lifters. Caused me more than a little angst over the last 24 hrs, which required me to have a few frosty beverages to get my temper in check!

That being said, thanks to all for the input. Ive already learned a few things from reading through the forum and will continue to do so.

So now I have to ask if anybody else has had the steering shaft issue? Ill update once I get though the process in case it comes up for anybody else.
 

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Happy for you that it wasn't something more serious. When you get it fixed, a comparison picture between the old bearings and the new bearings would be great for the site.
Thank you for your contribution to the Texas economy.....
I could say that I feel for California, but.....Nah!

Welcome to the forum....Lots of great people and great information here!
 

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Woodgetter said:
.....So now I have to ask if anybody else has had the steering shaft issue? Ill update once I get though the process in case it comes up for anybody else.
I had to replace intermediate steering shaft in my '03 Silverado, maybe not exact same issue, not sure. On another GM vehicle ('03 Cadillac DeVille) I had the steering shaft bearings go bad. I ended up going to junkyard and buying entire steering column, which turned out to be the easiest way to fix, and it only cost $150.

Please be sure and post exactly what is your problem, and how it turns out. Good luck. Glad it wasn't the engine! ;)
 

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Discussion Starter · #17 ·
Ha - I'm a Texas boy so completely understand! We are shopping for houses now in Little Elm but the market is insane...probably from all the Ca people migrating.

I'll see what pics I can get of the bearings and post.
 

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SilmarilS said:
I'm still baffled that after 100 years of combustion engine fabrication, they still can't build a reliable motor in 2021...

It's almost scary to buy a brand new vehicle (every brand).
They certainly can, but the constraints of the EPA to get every .00001 mpg saving are a huge burden. It is already getting unattainable which is why so many cars are going hybrid or electric, just to make the average end up where it needs too. GM will be all electric within a decade IIRC.
 
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