This Diesel Engine's Been Around For 40+ Years (And Reliability Is The Key)

40 years is a long time in the automotive world. While a few prized cars from the 1980s may be exploding in value, not many would consider their 40-year-old engine technology reliable. One diesel engine has withstood that test of time, though: the Cummins B-Series. Rudolf Diesel invented the diesel engine in 1897, but Clessie Cummins – and his Cummins Engine Company — would continue to refine the technology through a long list of patents and diesel engine designs.

The Cummins B-Series diesel is perhaps the best-known engine to come from all those years of experience. That familiarity is a product of Dodge using Cummins engines after powering its trucks with Mitsubishi Motors diesel engines. While the inline six-cylinder 6BT Cummins 5.9-liter (part of the B Series engines for agriculture) made its debut in 1984 for use in farm tractors, it didn't make its way into Dodge Ram trucks until 1989. The B-Series has undergone some changes to improve upon that original design over the years, ultimately giving us the 6.7L Cummins Turbo Diesel that's still available in heavy-duty Ram pickups today. Evolutions include the 24-valve 5.9L ISB from 1998 and the 6.7L ISBe introduced in 2007.

The Cummins diesel engines powering Dodge and Ram pickups are generally thought to be very reliable by their owners. In fact, the 12-valve 5.9L Cummins is often considered as one of the greatest truck engines of all time. Bruce Behner, a member of Cummins' Million Mile Club, bought his 12-valve Cummins used, with it having already driven 231,000 miles. At the time of recording a video for the official Cummins YouTube channel, the truck's six-digit odometer showed 015,050 miles, having already rolled over from its maximum of 999,999.

Even so, the few problems experienced by Cummins B-Series diesel engines shouldn't go unmentioned. Issues like the killer dowel pin and 53 block are reason enough to use caution if you're buying a 5.9 Cummins engine produced from its debut to 2002. The 6.7 Cummins isn't immune to problems, either, especially beginning with the 2019 model year. These issues mainly centered around failed hydraulic lifters that could ruin the camshaft. That was also the year Ram started using the infamous Bosch CP4.2 high-pressure fuel pump to feed the 6.7 Cummins.

Fortunately, all of the issues — except the 53 Block, which will eventually crack — have fairly simple solutions. Some of them, like the high-pressure fuel pump, have already been covered for owners under recalls.