The 5.9 Cummins is a 5.9-liter (359 cubic inch) inline-six turbo diesel used in Dodge Ram heavy-duty pickups from 1989 to 2007. Its bore and stroke are 4.02 x 4.72 inches, and its firing order is 1-5-3-6-2-4. It was built in three main versions, the mechanical 12-valve, the electronically controlled 24-valve and the high-pressure common-rail 5.9, with factory ratings rising from 160 hp in the earliest trucks to 325 hp in late high-output common-rail trucks. Ratings vary by year and transmission.
5.9 Cummins specs
| Spec | Value |
|---|---|
| Configuration | Inline six, turbocharged diesel |
| Displacement | 5.9 L (359 cu in) |
| Bore x stroke | 4.02 x 4.72 in |
| Firing order | 1-5-3-6-2-4 |
| Years in Ram pickups | 1989 to 2007 |
| Factory ratings | About 160 hp (early 12-valve) to 325 hp (late high-output common rail) |
5.9 Cummins versions
| Version | Years (Ram) | Fuel system |
|---|---|---|
| 12-valve | 1989 to 1998 | Bosch VE rotary pump, then P7100 inline pump |
| 24-valve | 1998.5 to 2002 | VP44 electronic rotary pump |
| Common rail | 2003 to 2007 | High-pressure common rail |
See Cummins generations and 12-valve vs 24-valve vs common rail.
Why the 5.9 is known for durability
The inline-six layout, a heavy cast-iron block and cylinder head, a gear-driven camshaft and conservative factory ratings give the 5.9 its reputation. Each version has its own known weak points, such as the killer dowel pin on some 12-valves and the VP44 injection pump on 24-valves; see 5.9 Cummins problems.
Transmissions behind the 5.9
Automatic 5.9 trucks used the 47RE and then the 48RE four-speeds, and manual trucks used heavy-duty five- and six-speeds; see 47RE vs 48RE and Cummins swap transmission options.
5.9 vs 6.7
The 6.7 that replaced it for 2007.5 has a larger 4.21 x 4.88 in bore and stroke and more power; see 5.9 vs 6.7 Cummins and 6.7 Cummins specs.
Cylinder numbering and firing order
Cylinders are numbered 1 to 6 from the front of the engine, and both the 5.9 and the 6.7 fire in the order 1-5-3-6-2-4; see firing order.
Oil and maintenance
Use the oil specification and capacity in your owner’s manual; diesel oil changes are larger and more frequent under severe use. Keep fuel filters fresh and drain the water separator; see water in diesel fuel.
Swaps
The 12-valve 5.9 is a popular swap engine because it runs without engine electronics; later versions need their computer and wiring. See Cummins swap.
Replacement engines
We list 5.9 Cummins engines on 5.9 Cummins engines; see 5.9 Cummins problems and how long a Cummins lasts.
More guides: Cummins killer dowel pin.
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