The later 04.5 to 07 Cummins 5.9s featured a five-hole nozzle, a narrower spray pattern, and to match that pattern, a different shaped piston bowl needed to be used. The pilot injection event is useful since it reduces noise and helps the main combustion event take place, and interestingly enough the addition of pilot injection is why common-rails are so much quieter than the mechanical engines which have only one injection event. The early 5.9 CR featured an 8-hole injector nozzle with a wide angle spray pattern, and there were two injection events per stroke: pilot (which injects a small amount of fuel to pre-heat the combustion chamber before ignition) and the main injection event, which is where the engine’s power comes from. While they share most of the same architecture, there are a few key differences which make certain parts not interchangeable, and most of those had to do with fuel delivery.

The 5.9 common-rail is divided into two separate groupings: the earlier 2003-04 models and the later 2004.5 to 2007. As part of our “What Breaks When” series, this week we’re taking a closer look at the 2003 to 2007 5.9-liter Cummins. While the 5.9 Cummins is a very robust engine, it does have a few weaknesses that can leave the truck stranded, but nothing that will lead to a catastrophic failure or meltdown.

2016 - 2023 Canyon/Colorado 2.8L DuramaxĢ003 marked the first year of a new body style pickup for Dodge, and to go along with its new looks, a new engine could also be found under the hood, and the major difference between it and the earlier 5.9 liter Cummins engine (and its Achilles heel) was the addition of common-rail fuel injection.

2003 5.9 cummins rear main seal