Just joined the 2021 Yukon lifter group

[mnemonicmark]

Good morning, everybody!

I have had my vehicle back since Friday. It runs well. No more noises, or shaking of the engine/exhaust system. Have driven 100+ miles over the weekend — all is well. (knocking on wood...)

@Geotrash: The mechanic told me the lifter failed because of poor hardening of the roller bearing in the lifter. At least that's GMC's theory/explanation. My question, how metal that is not hardened properly then caused damage on a hardened camshaft remains unanswered... Unless the camshaft also was poor metal.
The mechanic also offered his personal opinion: Poor lubrication and failure to do oil changes frequent enough and on time during the first 40-50k miles of the vehicles life. I bought it at 48k.

Several mechanics have now told me that they recommend oil/filter changes after ~4k miles - no matter what the oil life algorithm shows/calculates. In addition to that also checking that proper oil levels are always maintained — if the car burns oil. Even the smallest amounts of oil being used/burned means it compounds towards any — and in particular — longer-life oil cycles.

WalleyMikeIII: It was indeed the passive lifter on cylinder 3 that failed. Given the problems we know of with AFM/DFM that was a surprise. The fact that GMC (after some pressure) agreed to change all lifters — even if only one lifter had failed — suggests to me that there indeed could have been a manufacturing/specification problem with the lifters of a certain generation or a particular manufacturer.

I'm going on a 3000+ mile road trip next month and that should put the repair job and the new parts to a test. I'll update here again at some point.

/M

 

[Geotrash]

Good morning, everybody!

I have had my vehicle back since Friday. It runs well. No more noises, or shaking of the engine/exhaust system. Have driven 100+ miles over the weekend — all is well. (knocking on wood...)

@Geotrash: The mechanic told me the lifter failed because of poor hardening of the roller bearing in the lifter. At least that's GMC's theory/explanation. My question, how metal that is not hardened properly then caused damage on a hardened camshaft remains unanswered... Unless the camshaft also was poor metal.
The mechanic also offered his personal opinion: Poor lubrication and failure to do oil changes frequent enough and on time during the first 40-50k miles of the vehicles life. I bought it at 48k.

Several mechanics have now told me that they recommend oil/filter changes after ~4k miles - no matter what the oil life algorithm shows/calculates. In addition to that also checking that proper oil levels are always maintained — if the car burns oil. Even the smallest amounts of oil being used/burned means it compounds towards any — and in particular — longer-life oil cycles.

WalleyMikeIII: It was indeed the passive lifter on cylinder 3 that failed. Given the problems we know of with AFM/DFM that was a surprise. The fact that GMC (after some pressure) agreed to change all lifters — even if only one lifter had failed — suggests to me that there indeed could have been a manufacturing/specification problem with the lifters of a certain generation or a particular manufacturer.

I'm going on a 3000+ mile road trip next month and that should put the repair job and the new parts to a test. I'll update here again at some point.

/M

Thanks for following up. I think their theory is plausible. The roller bearings are what support the roller that rides on the cam, so if they're not hardened properly, then the roller itself will start to periodically drag like a bad shopping cart wheel and take out the cam lobe.

Seems we have a new failure mode for the lifters on these engines. First I've seen improperly hardened roller bearings as a root cause... that I can remember anyway.