The introduction of high-output 6.7L Cummins in 2019 was marketed as an evolutionary milestone for Ram, boasting jaw-dropping 1,000 lb-ft of torque alongside a compacted graphite iron block, stronger internals, and an updated valvetrain. However, the addition of the hydraulic lifters brought about some troubling issues.
What was to be an unobtrusive, low-maintenance update has quietly become the biggest failure of the newest Cummins generation.
Why the Switch to Hydraulic Lifters?
Starting in 2019, Ram decided to replace the traditional tappet-style lifters utilized from 1989-2018 with self-adjusting hydraulic lifters. The objectives were straightforward:
Reduce valvetrain noise
Eliminate the need for periodic valve lash adjustment
This was a step forward considering the use of hydraulic lifters in Power Stroke engines since the 90s. But the reasoning behind their adoption did not change the fact that the 2019+ 6.7L Cummins suffered from critical flaws.
The Problem: Inappropriate Design and Insufficient Lubrication
The hydraulic lifters in new Cummins engines suffer from:
- No needle roller bearings (Ford’s design feature)
- Static clearance that impede the oil-bore’s cooling capabilities
- Small-sized oil passages of the lift body
- Reluctance to newer higher-weighted oils
The situations is exacerbated by a steel dowel pin, which is supposed to prevent lifter rotation, backing out of the lifter body to cause a catastrophic engine failure.
Ram even went as far as issuing a TSB stating the use of 15W-40 engine oil with these engines would void the warranty.
Some Stages of Hydraulic Lifter Failure
Active symptoms are felt most during the cold starts:
- Tapping or ticking sounds which can be likened to a typewriter
- Sounds originating from the upper region of the engine block
- Almost all failures are noticed less than 100K miles, some 10K
In the intermediate progress stage of lifter failure:
- Burn and seize of the roller
- Gouging of the cam shaft lobe
- Circulation of metal shavings and oil contamination
- The onset of complete failure of the engine system
If out of warranty, replacing the engine would cost roughly $27000 from the dealer
The Repair Process
Lifter problems can be troublesome:
Taking off the front of the truck or lifting the cab may be required.
While removing the cam for in-frame repairs, the lifters need to be held up with magnets.
A specific trough is necessary for collecting the factory lifters.
This is not a quick and easy repair, and definitely not something the average truck owner would want to spend their time attempting.
Aftermarket Solutions to the Rescue
Solution: Flat Tappet Conversion (Hamilton Cams)
Hamilton will convert your Cummins to how it used to be with their flat tappet conversion, a full valvetrain overhaul.
Kit includes:
DLC-coated flat tappets
Hamilton’s 178/208 “efficiency” camshaft
Upgraded pushrods
Adjustable rocker arms with DLC trunnions
Benefits:
Long-haul trucking or heavy towing becomes easier with expanded reliability and proven performance.
Increased oiling and lubrication
Reduced friction and wear
Long-term durability
This is perfect for long-haul trucks or heavy towing applications where reliability is key.
Final Thoughts: Take Action Before It’s Too Late
While the 2019+ 6.7L Cummins is touted to be the most powerful ever, the valvetrain design is merciless. If you suspect your top-end noise is affected by lifters, or just want to have peace of mind, upgrading should be a priority.
(click image below to see video)
