Deeper Than The DPF

Emissions derates are an all-too-common occurrence on modern diesel trucks, but when a 67,000-mile 2020 Ram 2500 is throwing not only DPF performance and soot accumulation codes – but ash accumulation as well, it will raise some questions. With low miles and idle time, this system should have plenty of life left in it. Through testing, it was confirmed that the DPF was in fact plugged. Typically, there is an upstream issue that is the root cause of these problems, but with air, fuel, and turbocharger systems looking to be performing as they should and no supplemental codes, it made for a head-scratcher.

If you’re a 5th gen RAM owner, chances are that you’ve heard of (and lost sleep over) the issues with their hydraulic lifters. It may sound like a long shot on this one, but investigating the valvetrain on this truck proved to pay off. The exhaust pushrods on cylinders #2 and #5 had been taking a beating for some time and wearing down, which caused excessive valve lash and ultimately wreaked havoc downstream on the emissions system.

This is just one case of many in the world of 5th gen Cummins lifter failures. When it comes to the failures, there are two main failure modes:

1. Galling takes place in the hydraulic portion of the lifter and causes it to hang up. This then creates excessive valve lash and essentially hammers the pushrods into the rockers. Depending on severity, it causes wear in the pushrods and rocker or, in more extreme cases, can bend the pushrod.
2. Rollers locking up and/or rotating. This can happen when the guide slot in the block becomes worn and allows the lifter to turn inside of its bore. From there the roller can lock up and wipe out the camshaft.

Fortunately, this issue can be resolved with the use of the Hamilton Flat Tappet Conversion Kit. This kit allows you to convert your 5th gen back to manual adjustable rockers and flat tappet lifters, similar to what is used in the previous generations of Cummins engines. Although they are similar in style, the Hamilton kit leaves no stone unturned in its design improvements.

Forged Steel Camshafts

• These camshafts are forged rather than cut out of bar stock. This makes for a stronger and denser camshaft than others available on the market
• Upgraded camshaft that could be considered as a mild performance design

DLC-Coated Tappets

• Diamond-like carbon coating creates an extremely hard finish on the part that greatly reduces friction and wear on the components
• A gas carburized hardening process, followed by polishing, creates a smooth tappet to camshaft contact surface

Heavy-Duty Pushrods

• The pushrods in this kit are rated at over 3500 lbs. of buckling force as compared to the OEM pushrods, which are around 1800 lbs.
• This design allows minimal flex in the pushrod, which keeps valve timing precise and consistent

Upgraded Rocker Arms

• Along with the high-grade quality of the cast portion of the assembly, the ball and foot are gas carburized to reduce friction and wear, and trunnions are DLC-coated to provide for smooth operation and protect from potential galling

The installation process of this kit does require some expertise and specialty tooling to accomplish, but the kit itself is very complete and pretty straightforward for such a large-scale repair. The DLC coatings that are used provide for an easy break-in process due to their smooth, hard finish, but precautions should still be made to ensure an issue-free break-in process.

Some important steps to note during this install are:

• Pre-lubrication of components as they are installed
• Building oil pressure at the initial startup
• Run the engine for approximately 5 minutes at an elevated idle (1200-1500 RPM), then shut down and change the engine oil
• Once oil is changed, check valve lash after you run the engine up to operating temperature
• Re-check valve lash at 80,000 and 100,000 miles post installation
• Run quality oils to protect your internal components. Hamilton recommends the use of Valvoline Premium Blue as a more readily available oil or Schaeffer’s 700 15W-40 as a premium option

Outside of a huge increase in reliability of your engine, you may notice improved spool-up, a slight increase in MPG, and a little more of that traditional diesel engine sound after installation. Whether you are making repairs caused by one of these failures or going to it for peace of mind, this is a setup that you won’t regret.