Lifter question

[jayoco]

I have a question about all these lifter issues. The consensus is that it's caused by the DFM/AFM or fuel management acronym du jour.

So...Once my lifters fail and are repaired, won't a repeat failure be expected? DFM is still activated so what's to prevent future trouble.?

 

[waynehead99]

Long term… possibly. I am just now learning up on this topic myself. The consensus right now is that 2021 is more an issue because of a bad batch of lifters by one of GM’s suppliers.

I am anxiously waiting for the Range Tech unit to support the 2021s so that I can disable the feature, but more so because I don’t like the lag in the engine switching to full cylinder usage and notice it sometimes feels like its hunting between cylinders.

All the manufactures are doing something similar in fuel management to try and get that “better” rating for MPG, and my guess overall is that we will see in about 10 to 15 yrs if these engines will still be usable without major work.

 

[1BADI5]

Interesting fact for you guys to explore.

I was informed by a GM Master Tech, that if your truck has to have the lifters replaced, GM will or is extending your powertrain/engine warranty out to 100,000 miles.

So I would ensure to ask about this if you run into this situation.

 

[SSGUNNER]

Now that is some good info there.

 

[MarkUps]

Interesting fact for you guys to explore.

I was informed by a GM Master Tech, that if your truck has to have the lifters replaced, GM will or is extending your powertrain/engine warranty out to 100,000 miles.

So I would ensure to ask about this if you run into this situation.

well i go the 7yr/125k to be safe lol

 

[swathdiver]

I have a question about all these lifter issues. The consensus is that it's caused by the DFM/AFM or fuel management acronym du jour.

So...Once my lifters fail and are repaired, won't a repeat failure be expected? DFM is still activated so what's to prevent future trouble.?

AFM/DFM worst enemy is dirty oil. Running the wrong viscosity, non-Dexos approved oil and extended oil changes (5K+ miles) and folks are asking for trouble. For the most part the lifters work just fine, it is when the solenoid gets out of time or fails that causes the lifter to jam up and worse.

 

[1BADI5]

AFM/DFM worst enemy is dirty oil. Running the wrong viscosity, non-Dexos approved oil and extended oil changes (5K+ miles) and folks are asking for trouble. For the most part the lifters work just fine, it is when the solenoid gets out of time or fails that causes the lifter to jam up and worse.

I agree with that statement, but lifters dropping on a 3-5000 mile motor is another issue

 

[iamdub]

AFM/DFM worst enemy is dirty oil. Running the wrong viscosity, non-Dexos approved oil and extended oil changes (5K+ miles) and folks are asking for trouble. For the most part the lifters work just fine, it is when the solenoid gets out of time or fails that causes the lifter to jam up and worse.

I agree with that statement, but lifters dropping on a 3-5000 mile motor is another issue

Could it be that the extra debris in the oil from the new engine breaking in is comparable to gunk in the system from an aged engine ran with dirty oil?

 

[swathdiver]

I agree with that statement, but lifters dropping on a 3-5000 mile motor is another issue

I wonder if it is a timing problem, not ignition but timing of the DFM solenoids. I can't imagine how to figure all that out when every cylinder now has its own solenoid and any combination of cylinders can be dropped for increased fuel efficiency.

 

[1BADI5]

I wonder if it is a timing problem, not ignition but timing of the DFM solenoids. I can't imagine how to figure all that out when every cylinder now has its own solenoid and any combination of cylinders can be dropped for increased fuel efficiency.

Bad lifters are bad lifters? So time will tell

 

[Quark]

Alas, the only ones who might have a clue aren't talking - the GM engineers. Is it unknowable or is it unspeakable.

 

[chirp]

I think there may be two causes of 2021 lifter problems. One is theoretical, and the other is published and acknowledged by GM.

1. Caused by AFM/DFM. This is a theory brought forth by many; no GM bulletin published on the subject to my knowledge (please correct me if wrong).
2. Caused by faulty parts (lifter collapse). This occurred for models built during specific months of the 2021 model year. I don't have the "bad" build months on hand; others may have that information.

 

[Quark]

Yet these failures have been occurring on pickups for the past two years. GM had a bad production run of springs but I've never heard of a bad run of lifters that has been acknowledged.

 

[Fireman591]

My dealer has replaced bent push rods with no broken springs or collapsed lifters. This sure sounds like harmonics on the push rods from a piss poor design. Oh and those bent lifters did have wear marks right in the area of the lifter sidewall where the push rod could make contact with it.

 

[Geotrash]

My dealer has replaced bent push rods with no broken springs or collapsed lifters. This sure sounds like harmonics on the push rods from a piss poor design. Oh and those bent lifters did have wear marks right in the area of the lifter sidewall where the push rod could make contact with it.

Yeah, the guy makes a pretty good case that weak pushrods are the smoking gun. But who knows? The engines with the older AFM system had essentially the same lifters, rockers, pushrods and springs, and their failure mode was lifters failing to fully engage and getting damaged, with the root cause being either a fault in the VLOM or low oil pressure not providing enough energy for the lifters to reliably engage. The valve train geometry is slightly different in the Gen V engines though, so maybe that's enough to make the pushrods the weak link.

 

[Micahsd]

According to this new TSB it shows the bad lifters were installed in vehicles between Sept 1, 2020 and March 31, 2021.

https://static.nhtsa.gov/odi/tsbs/2021/MC-10197298-9999.pdf

 

[Quark]

I don't understand why a lot of us are trying to see the rosy side of this when we should be highly critical of a company pumping out an unreliable product. If you're a GM sales associate raise your hand otherwise smarten up.

"The aforementioned valve lifter problem affects 2019-and-later model-year..."

How GM Dealers Handle Engine Valve Lifter Issues

Affecting 5.3L L84 and 6.2L L87 V8 engines.

gmauthority.com

This does not suggest a bad batch of whatever but if it were a bad batch it is multi-year and GM's quality control is worse than a Yugo's. C'mon man!!!