Machinery & Truck PartsThe Cummins ISB 5.9 is a 5.9-liter (359 cu in) inline-six, 24-valve turbodiesel built from 1998.5 to 2007 — the electronically managed B-series best known for powering Dodge Ram 2500 and 3500 trucks, plus medium-duty trucks, buses, and RVs. It is prized as the last pre-emissions-aftertreatment 5.9. Machinery and Truck Parts stocks tested used ISB 5.9 engines, run-tested before shipping and backed by warranty. Call (800) 696-5459 with your truck or serial number for the right fit and a freight quote.
Cummins ISB 5.9 Engine Specifications
| Displacement | 5.9 L (359 cu in) |
| Configuration | Inline-6, 24-valve, turbocharged |
| Bore x Stroke | 4.02 in x 4.72 in |
| Compression ratio | 17.2:1 |
| Horsepower | approx. 215 to 325 hp (by year) |
| Peak torque | approx. 420 to 610 lb-ft |
| Fuel system | VP44 rotary pump (1998.5 to 2002) or Bosch CP3 common rail (2003 to 2007) |
| Emissions era | Pre-DPF |
| Dry weight | approx. 1,150 lb |
| Production years | 1998.5 to 2007 |
What Trucks and Vehicles Use the Cummins ISB 5.9
Dodge Ram 2500 and 3500 pickups (1998.5 to 2007), medium-duty and vocational trucks, school and shuttle buses, motorhomes and RVs, and industrial power units.
ISB 5.9 vs 6.7
The 24-valve ISB (1998.5 to 2007) is the electronic successor to the mechanical 12-valve 6BT. The ISB 6.7 replaced the 5.9 at model-year 2007.5, adding DPF and later DEF emissions hardware; the 5.9 is preferred by many buyers for its simpler, pre-aftertreatment design.
Common Cummins ISB 5.9 Problems and What to Check When Buying Used
On 1998.5 to 2002 (VP44) trucks, the signature weak points are the VP44 injection pump and the factory lift pump that feeds it — a confirmed lift-pump upgrade is a good sign. Watch for the cracked "53" casting block (about 1999 to 2001), APPS "dead pedal", and, on 2003 to 2007 common-rail engines, injector wear. Every engine we sell is run-tested before it ships.
Cummins ISB 5.9 Engines In Stock
Cummins ISB 5.9 Engine FAQ
What trucks use the Cummins ISB 5.9?
Mainly Dodge Ram 2500 and 3500 (1998.5 to 2007), plus medium-duty trucks, buses, motorhomes, and industrial equipment.
Is the 5.9 Cummins reliable?
Yes; its simple inline-six design is durable. On VP44 trucks (1998.5 to 2002), lift-pump maintenance protects the injection pump.
How many miles will a 5.9 Cummins last?
These engines are widely reported to run several hundred thousand miles with maintenance, with many exceeding 300,000 (owner experience, not a manufacturer-rated figure).
What is the difference between the 12-valve and 24-valve 5.9 Cummins?
The 12-valve (6BT, through 1998) is mechanically injected and predates the ISB; the 24-valve ISB (1998.5 to 2007) is electronic — first with the VP44 pump, then common rail from 2003.
What is the difference between the VP44 and common-rail 5.9 ISB?
1998.5 to 2002 trucks use a Bosch VP44 rotary pump; 2003 to 2007 trucks use high-pressure common rail with a Bosch CP3 pump, which is quieter, cleaner, and makes more power.
What are the most common 5.9 ISB problems?
VP44 pump and lift-pump failure and APPS "dead pedal" on 1998.5 to 2002; the cracked "53" casting block; and injector wear on 2003 to 2007.
ISB 5.9 vs 6.7 — which is better?
The 5.9 (through 2007) is simpler with no DPF or DEF; the 6.7 (2007.5 and later) is larger and more powerful but adds emissions hardware.
Do your ISB 5.9 engines come tested and with a warranty?
Yes; run-tested before shipping, warranty included, freight quoted nationwide.
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