The Ram Hemi engines have been in production for almost 20 years, with the supercharged 6.2-liter arriving in 2020 in the Ram TRX. Since all of the Hemis from the 5.7-liter to the 6.4-liter are of the same general parts bin, we’ll refer to the family in general. But the larger cubic-inch Hemi blocks have some differences from earlier Hemis including more nickel content, more webbing, and larger cooling passages, besides horsepower and torque specs.
The Hemi engine family has been a proven, reliable engine, but there have been problems off and on for years. Some are common enough they even have names, like the “Hemi tick.” But in general, there are plenty of Hemi examples that have north of 300,000 miles on them.
The 6.4-liter Hemis are similar but have increased displacement but no superchargers. They are available in the Ram 2500 and 3500 heavy-duty trucks, along with many other Dodge, Chrysler, and Jeep models.
Ram lifter and camshaft “Hemi tick” issues
In 2009, the Hemi engines received fixes for some recurring issues. But with the larger cubic-inch Hemis, there is a general agreement that the cam lifter angles are a problem because the lifters are too high in the block. The result is oil splash is not lubricating the lifters, leading to premature failure.
Some say that the ticking noise is just common to the design. Others say it is a result of the Multiple-Displacement System or MDS. The MDS is another trouble point we’ll get into next. But if poor lubrication is the cause, it leads to metal-on-metal contacts, which then leads to metal particles floating throughout the engine. If left alone, it can ultimately lead to engine failure.
This seems to be happening mostly with trucks at around 80,000 to 100,000 miles. Fixing the problem means replacing the camshaft and lifters, and replacing the oil pump. Once you get into that level of labor, it might be cheaper to replace the entire engine or go with a new long block.
Ram Hemi Multi-Displacement System Issues
The MDS used in these engines is for disabling four cylinders when the engine is operating in a cruising load. This saves on gas consumption. The engine will revert back to eight-cylinder operation for more power.
But at issue are the solenoids triggering the deactivation in the cylinders. If solenoid failure occurs, it tends to be blamed on the cooler deactivated cylinders. The speculation is that cooler oiling in these cylinders provides less lubrication. Each time deactivation is in the same cylinders. So the potential is usually with those cylinders.
Spark plug fouling is also said to be associated with those cylinders according to Tuning Pro. But these are all spitballing the problem and haven’t been determined to be the actual problem. So let’s call it a possible problem with the MDS as a whole.
Though not exactly common, misfiring has been reported. It usually shows up as fault codes, rough idle, and generally poor performance. If it does happen, it should flash a fault code. Keep in mind that there are 16 spark plugs and eight coil packs on these engines. That’s a lot of ignition parts that can go south.
The owner’s manual recommends replacing the plugs at 60,000 to 80,000 miles. Maybe around 40,000 to 50,000-mile replacement will eliminate the problem, or not? Coil packs should be able to go for 100,000, but being an electrical component, the hot-cold heat cycles arent’ the coil’s friend. So earlier replacement might also be worth doing.
So most of these issues revolve around maintenance. Replacing oil and oil filters, and spark plugs is not an expensive proposition. And replacing the coil packs won’t set you back much. A generally good brand of eight will run around $300 to $400.