BREAKING: GM is officially recalling the L87

[vcode]

Apologies if this one has already been posted. Looks like there are 3 bulletins involved. Owner notification in June. https://static.nhtsa.gov/odi/rcl/2025/RCLRPT-25V274-1598.PDF

 

[WalleyeMikeIII]

Apologies if this one has already been posted. Looks like there are 3 bulletins involved. Owner notification in June. https://static.nhtsa.gov/odi/rcl/2025/RCLRPT-25V274-1598.PDF

#445 and again in #483

 

[BADRIDES]

#445 and again in #483

(Dealers will inspect and, as necessary, repair or replace the engine.Vehicles that pass inspection will be provided a higher viscosity oil.)
Dealerships are NOT gonna tear engines down looking for damage. You are gonna have to come into the shop with a knocking noise before you get torn down or have a code. Dealerships dont have the man power to be tearing engines down looking for damage. If your engine sounds just fine that you are getting a 0-40 oil change.

 

[viven44]

There was discussion of "debris" in the crank oil passages and on the connection rods. The crank was also I believe the words were "machined out of tolerance"??? The crank is supposed to have a micro polishing of the journals before installation, this is not usually performed at foundry, but at the assembly plant shortly before the crank is installed.

I believe the bearings were scored with debris and may have started to delaminate and/or there were problems maintaining the hydrodynamic oil wedge due to surface finish and excessive clearance.

I think I'm aligned

I'm not buying this whole manufacturing defect "spin" yet.. call me a conspiracy theorist.. for those familiar with statistical process control / 6-sigma you can probably relate. Sure, it is a manufacturing defect, assuming the process wasn't centered to begin with.. we are talking a very high failure rate on this engine on 0W-20 from day 1 (2021).

Lets assume a crank journal and bearing process targets and tolerance is setup a certain way... and there is process tolerance for both manufacturing steps, and lets say the combined "output" tolerance is setup to accept 0W-20 or 0W-40, but in this hypothetical scenario the clearances are such that 0W-40 oil would put the manufacturing output "centered" and normally distributed with 6-sigma defectivity capability (<=3.4 defective parts per million failure rate).

It's my conjecture that what we have here is a shifted manufacturing process with 0W-20 usage where the clearances are on the high side for the oil, and thus in vehicles where the clearance was outside the capability of 0W-20, it resulted in failure. We have 3-5% failure rate here (area under the curve shown in red below).

GM can say "we didn't center the manufacturing process to begin with" or say "manufacturing defects". It's all perspective. You decide.

 

[Bkihum]

I do not think the bearings were too tight. I think it may have been a combination of things.

Understand that every engine built is "Cold Tested" on a device like a Spintron. If the engine was too tight at assembly the Spintron device should have detected higher current consumption of the electric motor spinning the engine.

If the motor was too loose, this may not have been picked up on the Spintron device.

I think if the engine was too loose, the oil pressure should have been an indicator, HOWEVER, the variable displacement pump may have masked a need for more oil and the pressure was not registering as low.

There was discussion of "debris" in the crank oil passages and on the connection rods. The crank was also I believe the words were "machined out of tolerance"??? The crank is supposed to have a micro polishing of the journals before installation, this is not usually performed at foundry, but at the assembly plant shortly before the crank is installed.

I believe the bearings were scored with debris and may have started to delaminate and/or there were problems maintaining the hydrodynamic oil wedge due to surface finish and excessive clearance.

Again, I believe the variable displacement oil pump may have masked a excessive clearance issue.

I have yet to see a 6.2l failure where anyone was ever alerted of an oil pressure problem. Few, if any engines had a noticeable knock or noise.
I believe every engine failed at highway speed.

At highway speed the 6.2l is under extreme engine loading at low RPM. Typically 1500-1700 RPM and when taking a very gradual rise in the road, maybe 50-100 feet over a mile or so, the engine loading will increase to between 70-100% depending on the grade and gear. Even if the transmission downshifts from 10th to 9th gear, this is only about 100 RPM increase.

I firmly believe the 0W20 oil cushion and ability to provide a thick enough layer on the crank and rod bearings was just beyond what ever damage may have occurred to the bearings or increased clearance.

Clearly there is some validity to this just because GM has proposed changing from 0W20 to 0W40 in engines that they believe had this manufacturing flaw. Some may characterize the flaw as a "defect" but I believe this is actually a combination of "Process Problems".

The Process of correctly grinding, polishing and cleaning the crank was not performed correctly.

The Process of making sure the connecting rods were clean and free of debris was not performed.

The Process of QA to verify that the engine oil clearances by way of monitoring the oil pressure was not reliable or even possibly covered up where a constant displacement oil pump may have indicated problems.

The Process of QA to pull every 100-250th engine for tear down and inspection was not performed. GM relied too much on automated assembly and testing and it is possible even the staff working in the assembly plants were not trained to identify problems or told they are to only perform X tasks and that the testing would identify any out of spec/bound conditions.

So sad all the way around. This was avoidable. Unfortunately now the end customers of 3 model years of multiple vehicles are caught in the middle of this. 600,000k or so engines in question?? What is the right answer???

All I can say is I am on the customers side and I think GM so poorly addressed this issue that they should make a public apology an get their clearly explain what they are planning to do to address this issue and how long they think it may take.

I expect this to take 18-24 months if they have to build and replace a large number of engines.

But the remedy is VERY unclear at this moment and there appear to be differences in the remedies. Maybe there was a false start, maybe Management has come to their senses?

We shall see.

I think your idea of the unfortunate outcome of this mess is very close to reality.
I worked for 42 years in an automotive assembly plant in different departments all over the plant. Your words bring back memories of things that happen from either laziness or the pressure of “ make production goal”.
Its always the customer that pays the price.
I had three 6. 2 engines failed and it was a terrible experience.

 

[Mma-007]

I think I'm aligned

I'm not buying this whole manufacturing defect "spin" yet.. call me a conspiracy theorist.. for those familiar with statistical process control / 6-sigma you can probably relate. Sure, it is a manufacturing defect, assuming the process wasn't centered to begin with.. we are talking a very high failure rate on this engine on 0W-20 from day 1 (2021).

Lets assume a crank journal and bearing process targets and tolerance is setup a certain way... and there is process tolerance for both manufacturing steps, and lets say the combined "output" tolerance is setup to accept 0W-20 or 0W-40, but in this hypothetical scenario the clearances are such that 0W-40 oil would put the manufacturing output "centered" and normally distributed with 6-sigma defectivity capability (<=3.4 defective parts per million failure rate).

It's my conjecture that what we have here is a shifted manufacturing process with 0W-20 usage where the clearances are on the high side for the oil, and thus in vehicles where the clearance was outside the capability of 0W-20, it resulted in failure. We have 3-5% failure rate here (area under the curve shown in red below).

GM can say "we didn't center the manufacturing process to begin with" or say "manufacturing defects". It's all perspective. You decide.


View attachment 456469

This might answer your doubts. The dude is a board certified oil specialist and talks about how he helped gm in a study with showing proof of said study.

 

[Stbentoak]

I think your idea of the unfortunate outcome of this mess is very close to reality.
I worked for 42 years in an automotive assembly plant in different departments all over the plant. Your words bring back memories of things that happen from either laziness or the pressure of “ make production goal”.
Its always the customer that pays the price.
I had three 6. 2 engines failed and it was a terrible experience.

To sum that up they put production and assembly line speed over quality control. There are multitude of factors that come into play here. Material compositions, tolerances in or out, surface finish of parts, contamination, oil itself and its pressure, oil flow, Fatigue, and I'm sure there are many other things.
I worked for 36 years making aircraft engine hot zone parts for military and commercial engines... Critical parts...If Pratt Whitney, GE, or Rolls Royce worked like this, planes would be falling out of the sky daily. Thank God they have the foresight, controls (and controls of vendors...) and traceability in place and testing to make sure this doesn't happen.....

 

[WalleyeMikeIII]

(Dealers will inspect and, as necessary, repair or replace the engine.Vehicles that pass inspection will be provided a higher viscosity oil.)
Dealerships are NOT gonna tear engines down looking for damage. You are gonna have to come into the shop with a knocking noise before you get torn down or have a code. Dealerships dont have the man power to be tearing engines down looking for damage. If your engine sounds just fine that you are getting a 0-40 oil change.

I tend to agree w/ you, but the information about the exact inspection procedure for customer cars on the road has not been released.
The 000 and 001 Recalls/TSB both say they only apply to vehicles in dealer inventory -- even though if I look up my VIN on GMC's recall site, it says my vehicle has the 000 recall/TSB. So, this is the most confusig part, unless newer versions of the 000, 001, and 002 Recall/TSB's exist, but have not yet been published where the general public can get to it.

 

[fredtufts]

I do not have good data on the 0W20 on my 6.2l, it was drained at 544 miles!

But with the variable displacement oil pump, I think the oil pressure was probably around 25-30 PSI. The guys with the 2025's can display the oil pressure in a digital numeric form unlike the 2024 and earlier unless some of the pickups had a different dash display.

I have never heard of a 6.2l failure ever that someone was informed of an oil pressure problem before the engine seized. I do not think oil pressure is the problem, I think maybe loose bearing clearances, 0W20 oil that was too thin, not enough oil cushion and/or hydrodynamic oil wedge and way too high of a Low RPM/High Torque load at highway speeds between 60-75 MPH. Engine loading with headwinds and/or very slight grade increase (50-100 feet over 0.5-1.0 miles) will cause the engine loading to spike to 70-100% easily and may sustain for a while depending on conditions.

Good analysis, James. But if the thinner 0w20 oil contributed to the problems, it is maddening that GM continues to suggest 0w20 oil on replacement engines build after the alleged defect dates. You would think they would recommend 0w40 or 5w30.