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Posted

What is the date range of bad lifters on the 21 models? I thought all AFM and DFM models of all years were subject to this, Are some 21 models more at risk? What percentage of trucks fail? Should I have purchased a Ram Hemi?

Posted
21 minutes ago, dgstarr63 said:

What is the date range of bad lifters on the 21 models? I thought all AFM and DFM models of all years were subject to this, Are some 21 models more at risk? What percentage of trucks fail? Should I have purchased a Ram Hemi?

straight from GM

 

"Breakpoint for the models effected September 1, 2020 to March 31, 2021"

  • Thanks 1
Posted (edited)
41 minutes ago, luke1333 said:

straight from GM

 

"Breakpoint for the models effected September 1, 2020 to March 31, 2021"

Before that even, Starting in June of 2020

  https://gmauthority.com/blog/2020/09/new-service-bulletin-addresses-valve-spring-issues-in-gm-v8-engines/

 

https://static.nhtsa.gov/odi/tsbs/2020/MC-10181159-9999.pdf

Edited by steelcity
Posted

I'm going to read all (5) pages of the replies, but just wanted to join the bad lifter party.  Trail Boss LT 2,990 miles.  Built in January 2021.   The bad / stuck lifter caused the push rod to bend.  Lots of misfires..etc   Horrible situation, as it occurred on vacation about 150 miles from home.

 

I just got my truck back 5min ago, I was comparing the repair order notes to what I'm seeing online.   Took 3 weeks to get the truck back because of backorders on all parts involved.   

 

The service center mentioned this is a problem with the 21s, but mentioned that the new OEM lifters from GM are "updated" parts compared to what was factory installed just a few months ago.   My biggest complaint here is that (1) it wont be a recall because too much labor is involved, (2) they didn't replace all of the lifters while they were in there, that's not how GM operates.

Posted

After many hours of study on this topic, I  believe that not all of the lifter failures are a result of lifter defects. Many are failed a second time after GM replaces them.  These issues are most likely due to computer issues which get the timing off on when to collapse and re energize the lifters.  I recommend driving in 7 low on an 8 speed or 9 low on on a 10 speed vehicle until you can install a Range disabler. From park shift into low, then click up until the desired gear is selected. The transmission will not shift higher than this gear and the AFM or DFM are disabled. Risking engine damage is not worth a savings of one mpg.

Posted

How much of these issue we are seeing are related to C19 with factories being shut down across the globe or at minimal personal operating them.  I work the the clothing industry & the last year of our goods being produced have failed to meet standards that didn't happen prior to C19.  I'm sure it's related to the work or lack of during this timeline.

Posted
3 hours ago, dgstarr63 said:

After many hours of study on this topic, I  believe that not all of the lifter failures are a result of lifter defects. Many are failed a second time after GM replaces them.  These issues are most likely due to computer issues which get the timing off on when to collapse and re energize the lifters.  I recommend driving in 7 low on an 8 speed or 9 low on on a 10 speed vehicle until you can install a Range disabler. From park shift into low, then click up until the desired gear is selected. The transmission will not shift higher than this gear and the AFM or DFM are disabled. Risking engine damage is not worth a savings of one mpg.

I have read several times, this does not disable DFM on 2019 and newer trucks.

Posted
16 hours ago, dgstarr63 said:

After many hours of study on this topic, I  believe that not all of the lifter failures are a result of lifter defects. Many are failed a second time after GM replaces them.  These issues are most likely due to computer issues which get the timing off on when to collapse and re energize the lifters.  I recommend driving in 7 low on an 8 speed or 9 low on on a 10 speed vehicle until you can install a Range disabler. From park shift into low, then click up until the desired gear is selected. The transmission will not shift higher than this gear and the AFM or DFM are disabled. Risking engine damage is not worth a savings of one mpg.

 

12 hours ago, Adamace1 said:

I have read several times, this does not disable DFM on 2019 and newer trucks.

 

I have read other forums that blame DFM as well.  Perhaps I will buy the (~$200?) kit to prevent this from happening again

 

Posted

I have a brand new 2021 Chevy trail boss z71 and I had lifters crap out on me with just 4,300 miles on the truck. They had the truck for almost 2 weeks and had to replace a ton of internals in the motor as well. Super wild that it happened this early. 

Posted
On 7/22/2021 at 4:39 PM, Adamace1 said:

I have read several times, this does not disable DFM on 2019 and newer trucks.

 

Are you saying that driving in L9 on the 10-speed isn’t shutting off DFM?

Posted
1 hour ago, EricTheRed said:

 

Are you saying that driving in L9 on the 10-speed isn’t shutting off DFM?

That's what alot of people have said. Including people on this forum with aftermarket exhaust, they can still easily hear the DFM still working when in L9 or L7 depending on the transmission.

Posted

I copied this from the 2020 Silverado Service Manual.  I is not entirely clear what they mean by "low gear ranges".

 

Conditions for DFM Operation

The conditions listed below determine when cylinder deactivation is enabled.

  • Engine coolant temperature is between 40−126°C (100−264°F)
  • Engine has been running for greater than 20 s
  • Engine oil pressure is between 187−585 kPa (27−84 psi)
  • Engine oil temperature is between 20−128°C (68−262°F)
  • Engine speed is between 700 and 2675 rpm
  • Ignition voltage is greater than 11 V
  • Transmission is not in, neutral, park, first, second, or reverse gear
  • Vehicle is not in heater performance mode
  • Vehicle is not in tip in bump acceleration mode
  • Vehicle is not in oil aeration mode
  • Vehicle is not in low gear ranges
  • Vehicle speed is greater than 13 kph (8 mph)
Posted
17 minutes ago, dgstarr63 said:

I copied this from the 2020 Silverado Service Manual.  I is not entirely clear what they mean by "low gear ranges".

 

Conditions for DFM Operation

The conditions listed below determine when cylinder deactivation is enabled.

  • Engine coolant temperature is between 40−126°C (100−264°F)
  • Engine has been running for greater than 20 s
  • Engine oil pressure is between 187−585 kPa (27−84 psi)
  • Engine oil temperature is between 20−128°C (68−262°F)
  • Engine speed is between 700 and 2675 rpm
  • Ignition voltage is greater than 11 V
  • Transmission is not in, neutral, park, first, second, or reverse gear
  • Vehicle is not in heater performance mode
  • Vehicle is not in tip in bump acceleration mode
  • Vehicle is not in oil aeration mode
  • Vehicle is not in low gear ranges
  • Vehicle speed is greater than 13 kph (8 mph)

Well there you go. Just put it second gear. It will disable DFM. You may get 50k out of your motor and get 3mpg doing it, but lifters should be good....

  • Haha 2
Posted
2 hours ago, dgstarr63 said:

I copied this from the 2020 Silverado Service Manual.  I is not entirely clear what they mean by "low gear ranges".

 

Conditions for DFM Operation

The conditions listed below determine when cylinder deactivation is enabled.

  • Engine coolant temperature is between 40−126°C (100−264°F)
  • Engine has been running for greater than 20 s
  • Engine oil pressure is between 187−585 kPa (27−84 psi)
  • Engine oil temperature is between 20−128°C (68−262°F)
  • Engine speed is between 700 and 2675 rpm
  • Ignition voltage is greater than 11 V
  • Transmission is not in, neutral, park, first, second, or reverse gear
  • Vehicle is not in heater performance mode
  • Vehicle is not in tip in bump acceleration mode
  • Vehicle is not in oil aeration mode
  • Vehicle is not in low gear ranges
  • Vehicle speed is greater than 13 kph (8 mph)

 

Wtf is tip in bump acceleration, and oil aeration mode. Anyone who knows next to nothing about engines and oil, knows you don't want oil aeration, EVER. Did you write that?

 

Cylinder deactivation has been around for ever and no one has heard of failing lifters? It doesn't matter what generation its in. Lifters that are designed to collapse and stop doing their intended job will always fail. Why? Because your asking the part to do something it really shouldn't be doing (unless you've tuned it out)

 

But its ok. Soon GM will stop having to design engines (if they haven't already). Vehicle Development cost's will drop dramatically, the number of humans needed to make the vehicles will drop dramatically, Material cost for vehicles will rise slightly. They'll charge way more money, the people will pay way more money, no more cylinder deactivation, everyone's happy.

 

Until people realize batteries suck. The used ICE vehicle market will sky rocket. Gasoline will skyrocket. But everyone's happy because they have an ice powered vehicle. Until lifters start failing because of cylinder deactivation... 

 

But its ok because gasoline will no longer be affordable for most people. And electric vehicles wont be afforable for most people. Anyone see where this is going?

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