At Least 36 L87 / 6.2L Engines Failed After Recall Inspection

[2024 White Tahoe]

The NHTSA may be expanding their investigation involving the GM safety recall of hundreds of thousands of vehicles equipped with the L87 / 6.2L engine, after at least 36 reports of the engines failing after passing the safety recall inspection and oil use modification process: https://gmauthority.com/blog/2026/01/nhtsa-investigating-post-recall-gm-6-2l-l87-engine-failures/

 

[Scarey]

Engineered solution, that was funny as sheet. The only thing engineered was the make believe fix.

 

[blanchard7684]

The "pico scope test" was a cruel hoax. There was always going to be some units that passed the test but failed later on.

 

[kurtibm]

"The goal of the thicker oil was to increase the protective film between components, attempting to compensate for potential imperfections.(Huh? How about some precision machining for once) However, the NHTSA’s latest filing notes that complaints “allege failures of both remedies,” meaning engines that got new oil and those that were completely replaced are still failing."
I was always taught that the first rule when you find yourself in a hole was to "stop digging". GM must have missed that lesson.

 

[ducfan]

It just doesn't seem to me as if Mary Barra is a car person. She should not be running GM.

 

[WalleyeMikeIII]

I guess I'll file a complaint too...that will take us to 37!!

 

[Fless]

I guess I'll file a complaint too...that will take us to 37!!

Why not add the links from that other post here (the NHTSA links)?

 

[tom3]

Top of the list here:

NHTSA Investigations by Manufacturer

NHTSA Investigations by Manufacturer

data.transportation.gov

 

[zbad55]

As I have mentioned before in previous threads is the best outcome for anyone with an affected engine should hope to fail the PICO test and receive a new engine, changing oil viscosity for a badly machined crank shaft didn't pass muster.

 

[kurtibm]

a badly machined crank shaft didn't pass muster.

I suspect they are never 'mustered'.

 

[PPK_]

Engineered solution, that was funny as sheet. The only thing engineered was the make believe fix.

i did not think testing at 2k rpm was a good idea. Oil pressure is way higher than at idle... this would hide a bearing knock-instead of making the sound easier to hear as it would with lower oil pressure at idle.

also... with the other things running.. like a alternator, bearings in the belt.. you have to figure out which one is making the noise.


not impressed... other than fooling the regulators that this is a good idea. its not....

 

[blanchard7684]

i did not think testing at 2k rpm was a good idea. Oil pressure is way higher than at idle... this would hide a bearing knock-instead of making the sound easier to hear as it would with lower oil pressure at idle.

also... with the other things running.. like a alternator, bearings in the belt.. you have to figure out which one is making the noise.


not impressed... other than fooling the regulators that this is a good idea. its not....

It seemed to be a stretch (putting it very nicely) that a "pico" test would uncover incipient bearing failure.

The pico test is a vibration assessment using an externally mounted transducer

For one, an externally mounted transducer is not accurate enough to gauge a journal bearing's health. What is needed is a proximitor probe that directly measures shaft motion. From this data orbital plots and spectral plots and other plots can be made that show if the bearings are in distress.

GM is in no position to attempt this as there is no realistic way to put a prox probe near the bearings.

The only way an external transducer can work is if GM had solid reference plots and traces to go off of.

So when something passes or fails on this it is still a judgement call of sorts.

Secondly, this pico assessment is a snap shot in time.

Bearing condition is a continuum. When a bearing is for sure failed then a pico test with external transducer can show this. The spectrum will have broad noise floor and multiples of 1x running speed spikes. For sure the pico test could get this part of the continuum accurately.

But early stage failure won't be accurately captured (per the above). And change over time can't be assessed as this is a one time look at the bearings.

So the folks that pass the pico test only passed a very crude and inadequate assessment of the bearings.

 

[kurtibm]

It seemed to be a stretch (putting it very nicely) that a "pico" test would uncover incipient bearing failure.

The pico test is a vibration assessment using an externally mounted transducer

For one, an externally mounted transducer is not accurate enough to gauge a journal bearing's health. What is needed is a proximitor probe that directly measures shaft motion. From this data orbital plots and spectral plots and other plots can be made that show if the bearings are in distress.

GM is in no position to attempt this as there is no realistic way to put a prox probe near the bearings.

The only way an external transducer can work is if GM had solid reference plots and traces to go off of.

So when something passes or fails on this it is still a judgement call of sorts.

Secondly, this pico assessment is a snap shot in time.

Bearing condition is a continuum. When a bearing is for sure failed then a pico test with external transducer can show this. The spectrum will have broad noise floor and multiples of 1x running speed spikes. For sure the pico test could get this part of the continuum accurately.

But early stage failure won't be accurately captured (per the above). And change over time can't be assessed as this is a one time look at the bearings.

So the folks that pass the pico test only passed a very crude and inadequate assessment of the bearings.

And this test is (theoretically) being performed by the same "technicians" that stripped out your oil pan drain plug.

 

[PPK_]

It seemed to be a stretch (putting it very nicely) that a "pico" test would uncover incipient bearing failure.

The pico test is a vibration assessment using an externally mounted transducer

For one, an externally mounted transducer is not accurate enough to gauge a journal bearing's health. What is needed is a proximitor probe that directly measures shaft motion. From this data orbital plots and spectral plots and other plots can be made that show if the bearings are in distress.

GM is in no position to attempt this as there is no realistic way to put a prox probe near the bearings.

The only way an external transducer can work is if GM had solid reference plots and traces to go off of.

So when something passes or fails on this it is still a judgement call of sorts.

Secondly, this pico assessment is a snap shot in time.

Bearing condition is a continuum. When a bearing is for sure failed then a pico test with external transducer can show this. The spectrum will have broad noise floor and multiples of 1x running speed spikes. For sure the pico test could get this part of the continuum accurately.

But early stage failure won't be accurately captured (per the above). And change over time can't be assessed as this is a one time look at the bearings.

So the folks that pass the pico test only passed a very crude and inadequate assessment of the bearings.

This PICO is... a government solution... if i thought i had a bearing making noise... i would listen.. check the oil pressure.. i would check the filter/put a new one in.. check the drain oil.. look at the drain oil.. take off each plug.. listen again... so on and so forth. i would not want to be wrong and lose a block. i don't even know if i would use a vibration study. it only indicates there might be an issue... then again you might use Vibration as you pull off each plug.

i have used vibration analysis at work.. you spend a lot of time determining if it is a roller bearing.. a gear and so on.. anyway.. the regulator DOT... is not top of anything.

 

[Marky Dissod]

Y'know what would've saved at least a few of these engines, and given the rest of us much more to learn from?
If GM had had the wherewithal to remove the suspect L87 oil pans. More expensive than a PICO test? Likely.

Hell, if GM had just drained out all the oil, and then stuck a flexible scope in the pan and looked for swarf ...