Rattle/grinding noise at 25-35 mph, mechanic told me AFM and lifters need to be changed.

[Dustin Jackson]

@iboughtatahoe23 I see. Well at least our test was successful, pick your preferred way of disabling AFM and proceed

 

[iboughtatahoe23]

Can anyone tell me if it is safe to drive in M? Like in 5th all the time?

 

[wjburken]

Personally, I think your situation is more of a now thing instead of a later thing. From what you are describing, you very likely have compromised lifters and the longer you run them, whether they are making noise or not, the greater the risk that you will have a catastrophic failure of a lifter which can take out your cam completely and send metal through your motor.

 

[iboughtatahoe23]

I also hear a light tap on the right side wheel well area. Thought it was exhaust leak but it’s on the complete opposite side of the broken stud

Pop says “sounds like a normal lifter going up and down”

 

[iboughtatahoe23]

Personally, I think your situation is more of a now thing instead of a later thing. From what you are describing, you very likely have compromised lifters and the longer you run them, whether they are making noise or not, the greater the risk that you will have a catastrophic failure of a lifter which can take out your cam completely and send metal through your motor.

Then drop a crate motor in and we good.

 

[iboughtatahoe23]

Personally, I think your situation is more of a now thing instead of a later thing. From what you are describing, you very likely have compromised lifters and the longer you run them, whether they are making noise or not, the greater the risk that you will have a catastrophic failure of a lifter which can take out your cam completely and send metal through your motor.

I hear you man, but it’s tough bc I have this on a loan and don’t wanna throw money at it if I don’t know 100% that it’s the lifters

 

[iboughtatahoe23]

@iboughtatahoe23 I've heard good things about this guy, this will be cheapest option in tuning AFM out: https://lt1swap.com/afm_delete.htm

Seems kinda inconvenient I’d be out of a car for a few weeks, got a job to get to that’s miles away so not sure how that would work. Might just buy that range AFM disabler and call it a day

 

[iboughtatahoe23]

Personally, I think your situation is more of a now thing instead of a later thing. From what you are describing, you very likely have compromised lifters and the longer you run them, whether they are making noise or not, the greater the risk that you will have a catastrophic failure of a lifter which can take out your cam completely and send metal through your motor.

Also not experiencing any lifter failure symptoms I don’t think… what are the symptoms?

 

[tom3]

On our Tahoe putting the shifter in M and selecting the 6th top gear also reverts to normal operation with the V4 and V8 mode. I notice ours does vibrate a bit in V4 mode with a bit of a load just before it switches to V8. I'd love this system - if it was more reliable.

 

[wjburken]

Also not experiencing any lifter failure symptoms I don’t think… what are the symptoms?

Well…..When I had a lifter fail on my 2007 non-AFM 6.2L the symptoms where a loud screeching/tap sound. Nothing else. No misfires, no codes, nothing.

When I had a AFM lifter failure on my 2013 AFM 6.2L, the symptoms were a loud tapping sound. No misfires, no codes.

The fact that it is dependent on AFM actuation, the only mechanical aspect of that is literally the lifter expanding and collapsing. If it doesn’t fully go into AFM position, you won’t get a misfire because the motor isn’t trying to fire that cylinder.