NHTSA opens preliminary probe into more than 870,000 GM vehicles

[cjlewis]

For background: 2023 Denali Ultimate. Blown engine replaced @ 16K. Currently have 56K miles (total).

New engine wasn’t part of the VIN recall that was mentioned earlier in this thread.

Does anyone know what triggered that partial re-call by VINs? Seems like GM found something wrong or identified a supply chain or manufacturing issue. Not sure if this is related to the larger investigation though or a “one-off”. Would be interesting to see if engine issues by year are declining or remaining constant.... however we may never know.

 

[jfoj]

For background: 2023 Denali Ultimate. Blown engine replaced @ 16K. Currently have 56K miles (total).

New engine wasn’t part of the VIN recall that was mentioned earlier in this thread.

Does anyone know what triggered that partial re-call by VINs? Seems like GM found something wrong or identified a supply chain or manufacturing issue. Not sure if this is related to the larger investigation though or a “one-off”. Would be interesting to see if engine issues by year are declining or remaining constant.... however we may never know.

So you have any specifics about what happened to the engine at 16k miles?
Spun bearing(s), which one(s), etc

 

[jfoj]

So just putting this info out there for a point of reference.

My 2024 Yukon build date was 8/2024, have not determined if I can actually find the Julian build date easily yet.

The 6.2l engine in my 2024 Yukon has a Julian build date of 24197 which means the engine was built on Monday July 15, 2024. So this could be anywhere from 2-6 weeks before the vehicle was built. Most likely 2-4 weeks before the vehicle was built because often the plants close the last 2 weeks of August for the next model year ramp up and to address any change over in tooling or assembly that needs to be tweaked. But I have found some info that due to the mid cycle refresh the 2025 Yukon production date is scheduled for regular production on Oct 7, 2024 a bit delayed and not unexpect for a refresh model.

Not sure if there is a cutoff window for problems with 6.2l engines for for the 2024 model year vehicles. I read somewhere that the 2025 6.2l were supposed to be "fixed". Not sure what this means and not sure when the 6.2l build dates for the 2025 model year vehicles would have started. Since new model years start usually starts in September, then the engines for the 2025 model year could have likely been built in late July or for the first few weeks of August as a guess, could have been later due to the Oct 7, 2024 production cycle for the 2025 models. But with the run on replacement 6.2l engines, not sure if the replacements are built on the same assembly line and pulled short of some of the last component installation and if any of this would through a monkey wrench in overall delivery and plans for the 2025 models.

This is all based on "typical" production cycles that I have been familar with over the years, but like anything the date ranges could vary.

This info for typical and general maufacturing and assembly windows.

 

[kmcintosh]

For background: 2023 Denali Ultimate. Blown engine replaced @ 16K. Currently have 56K miles (total).

New engine wasn’t part of the VIN recall that was mentioned earlier in this thread.

Does anyone know what triggered that partial re-call by VINs? Seems like GM found something wrong or identified a supply chain or manufacturing issue. Not sure if this is related to the larger investigation though or a “one-off”. Would be interesting to see if engine issues by year are declining or remaining constant.... however we may never know.

I don't remember seeing a recall list.

 

[jfoj]

No recall at this point, only thing that has really been put out there are a few GM bulletins.

The 1st is a Customer Service Program bulletins that is quite a bit "wiggly" for the Oversize Lifter Bores. Does not disclosed specific VIN's or Build Month/Year to the public. Just seems to cover model year 2023 only. But did indicate affected customers would be notified. Rather vague IMHO.

The 2nd is a "Service Bulletin" that references engine Main Bearing Failures for a wide variety of engines over model years 2019-2024. But in this instance for this forum we are primarily focused on the L84 5.3l and L86 6.2l for model years 2021-2024

Seems to be 2 related bulletins.

1. For Oversize Lifter bores and supposedly GM was to notify owners, but I have not heard anyone receiving notification. This is for 2023 model year ONLY based on the bulletin unless another newer version has been released. The resolution of for the VIN's affected by the oversize Lifter Bores is:

"What We Will Do: Your GM dealer will replace the engine. This service will be performed for you at no charge until May 31, 2026. After that, any applicable warranty will apply."

https://static.nhtsa.gov/odi/tsbs/2024/MC-10253536-0001.pdf

2 . For Crankshaft Bearing Failures. This appears to be for BOTH the L84 5.3l AND L87 6.2l from model year 2021-2024! No real info other than referring dealer service personel to other Technical Service Bulletins for "repair information". No discussion if GM will cover any of the costs associated with these problems beyond the original Powertrain Warranty! Best bring a full wallet or get ready to fight this one.

https://static.nhtsa.gov/odi/tsbs/2024/MC-10249946-0001.pdf

I think the NHTSA is looking into these problems to determine what, if anything GM should do if the numbers support a "Recall". If there is not a "Recall" there may be some financial asssitance foer the "Main Bearing Failures"? Seems to me the Oversize Lifter Bores will directly contribute to Main Bearing failure since the main bearings are in the oiling path AFTER the camshafter and lifters!

There may be other "Customer Service Program" bulletins I have missed or not found and/or there may be updated or new "Bulletins" either to support the customer and/or dealers released in the future on these engine failures. Up to possibly including a government mandated "Recall".

 

[TheAgency]

My 2023 Yukon Denali 6.2 just went into the dealer on Monday for engine issues along these lines, presumably for bearing failure but possibly others, though lifters were ruled out. 34k miles, oil changes every 6,000 with AmsOil signature and was always fussy with my fuel quality. The dealer has had it all week and they are still tearing it apart.

I started noticing the engine run rough this past January during a bout of very cold Minnesota weather and chalked it up to outdoor temperature. Then just last week, it started making a noise almost like a "jake brake" when I slowed to a stop or near stop, and then made the same noise again as I accelerated out of it. Once I was up to speed it was fine. Starting it up in the garage, hood open, there would be an extremely noticeable deep knocking noise coming from the middle/bottom of the engine.

Getting very frustrated with these. I had a 2021 6.2L Yukon Denali, equally well-cared for, that had all lifters replaced after about 55k miles.

This is my 9th GM Full Size V8 SUV/Truck and likely my last. The looks and interior of these T1XX are the best in the industry by far, but I'm seriously considering selling it once I get it back and going with another brand completely.

 

[KMeloney]

My 2023 Yukon Denali 6.2 just went into the dealer on Monday for engine issues along these lines, presumably for bearing failure but possibly others, though lifters were ruled out. 34k miles, oil changes every 6,000 with AmsOil signature and was always fussy with my fuel quality. The dealer has had it all week and they are still tearing it apart.

I started noticing the engine run rough this past January during a bout of very cold Minnesota weather and chalked it up to outdoor temperature. Then just last week, it started making a noise almost like a "jake brake" when I slowed to a stop or near stop, and then made the same noise again as I accelerated out of it. Once I was up to speed it was fine. Starting it up in the garage, hood open, there would be an extremely noticeable deep knocking noise coming from the middle/bottom of the engine.

Getting very frustrated with these. I had a 2021 6.2L Yukon Denali, equally well-cared for, that had all lifters replaced after about 55k miles.

This is my 9th GM Full Size V8 SUV/Truck and likely my last. The looks and interior of these T1XX are the best in the industry by far, but I'm seriously considering selling it once I get it back and going with another brand completely.

Yours sounds like the first (I’ve read about) to have given a “warning” that it was about to go.

 

[jfoj]

My 2023 Yukon Denali 6.2 just went into the dealer on Monday for engine issues along these lines, presumably for bearing failure but possibly others, though lifters were ruled out. 34k miles, oil changes every 6,000 with AmsOil signature and was always fussy with my fuel quality. The dealer has had it all week and they are still tearing it apart.

I started noticing the engine run rough this past January during a bout of very cold Minnesota weather and chalked it up to outdoor temperature. Then just last week, it started making a noise almost like a "jake brake" when I slowed to a stop or near stop, and then made the same noise again as I accelerated out of it. Once I was up to speed it was fine. Starting it up in the garage, hood open, there would be an extremely noticeable deep knocking noise coming from the middle/bottom of the engine.

Getting very frustrated with these. I had a 2021 6.2L Yukon Denali, equally well-cared for, that had all lifters replaced after about 55k miles.

This is my 9th GM Full Size V8 SUV/Truck and likely my last. The looks and interior of these T1XX are the best in the industry by far, but I'm seriously considering selling it once I get it back and going with another brand completely.

Sorry to hear about your vehicle. It sounds like you heard the bottom end problem before it hard failed, unless for some reason the noise if from the High Pressure Fuel Pump. Could alse be the thrust bearing going on the crank?

A few quesitons:
Assume you are the original owner?
What weight oil did you run? 0W20, 5W30 or other?
You indicated you were fussy about fuel quality, explain this please? 89, 91, or 93 Octane and a specific brand?
What is the build month and date on the vehicle?
Since your vehicle is a 2023, do you know if your vehicle fell within the "Oversize Lifter Bore" group? Were you ever notified by GM about this issue?

Please update the thread on what the dealer finds as well.

Just trying to gather more context on these failures.

 

[cjlewis]

So you have any specifics about what happened to the engine at 16k miles?
Spun bearing(s), which one(s), etc

#5 and # 6 rod bearings, spun crank case and metal in the oil pan.