Does anyone know the exact failure mechanism of the lifters?

[Dogged]

I've got almost 24k on my 2021 with no problems, but I typically run 150k+ miles between trucks. Has there been any actual info on what is failing and if we as owners can do anything to help prevent it?

These new trucks are calling for 0-20 oil which is super light, especially in hot weather and towing. Most likely so light to squeak out 0.001 MPG, probably at the long term expense of the engine. Maybe slightly heavier oil grades in the summer would be advantageous and provide better mechanical wear resistance? FYI, the 2020 6.2 calls for 5-20.

I'd love to know what's truly happening to feel better about long term ownership on this one.

 

[Fireman591]

Turning off the DFM would sure help. It is when those inactive cylinders fire up at just the wrong time that a push rod gets bent. The push rods are making contact with the lifter sidewall and causing harmonic bending of the push rod. If that cylinder happens to fire up when that push rod is already flexed it will get flexed into a permanent bend. Wear marks on the lower push rod just above the seat confirms the contact. Major design flaw compounded with the DFM system.

 

[Tiki]

I am a firm believer in more frequent oil changes as a strong preventative measure. I notice less noise overall going to ~50% on the OE system wear number.

 

[Micahsd]

There’s a TSB out that talks about how the bad lifters could be in vehicles built between Sept 2020 and March 2021.

Mine was built March 19th and so far no issues although I’m almost to 5,000 miles. Sounds like most fail between 5-12k miles.

 

[iamdub]

Turning off the DFM would sure help. It is when those inactive cylinders fire up at just the wrong time that a push rod gets bent. The push rods are making contact with the lifter sidewall and causing harmonic bending of the push rod. If that cylinder happens to fire up when that push rod is already flexed it will get flexed into a permanent bend. Wear marks on the lower push rod just above the seat confirms the contact. Major design flaw compounded with the DFM system.

Can the push rods be replaced with stronger aftermarket ones? Mine's an archaic 4th gen, but I got some .080" wall push rods in the largest diameter that'd fit (3/8") for mine when I needed some custom-length ones for my build. I did this just because the stock ones in the 3rd- and 4th-gen engines are a known weak link, even in a stock engine.

 

[avalonandl]

That is not much clearance on that pushrod——

 

[iamdub]

That is not much clearance on that pushrod——

It's not. But, it shouldn't flex. Not with .080" chromoly wall and my mild cam.

I still need/want to upgrade the trunnion bearings. When I have the rocker covers off, I'll inspect the push rods to see it they've been contacting. I might pop a cover off at the next oil change.

 

[avalonandl]

There is no pushrod that doesn't flex some. If you had high speed cameras you would be amazed the amount of deflection at 6,000 rpm.

 

[iamdub]

There is no pushrod that doesn't flex some. If you had high speed cameras you would be amazed the amount of deflection at 6,000 rpm.

I meant flex enough to contact. Regardless, you're right and it's still something I should check sooner than later. It sees 6000 RPM almost every time I drive it.

 

[Fireman591]

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