Cummins ISB 6.7L
Horsepower
350–430 hp
Torque
650–1075 lb-ft
Years produced
2007–2026
Aspiration
Turbocharged
- Configuration
- I6, 6.7 L
- Aspiration
- Turbocharged
- Builder
- Cummins
- Designers
- Unknown
- Years
- 2007–2026
Offered in: Dodge Ram 2500, Dodge Ram 3500, Ram 2500, Ram 3500
The 6.7-liter Cummins replaced the 5.9-liter ISB in Ram heavy-duty pickups partway through the 2007 model year. It is a turbocharged inline-six with a larger bore and stroke than its predecessor, and it uses exhaust gas recirculation and a diesel particulate filter. Its ratings rose in steps across two Ram generations, from 350 hp and 650 lb-ft at launch to 400 hp and 1,000 lb-ft from 2019 by one source's account. A 2025 update paired it with an eight-speed automatic.
What made it successful
It kept the Cummins name that Ram buyers already associated with durability while meeting the tighter emissions rules that took effect in 2007. Its torque ratings grew considerably over its run, which supported Ram's heavy-towing positioning.
Market position
For most of its run it was the only diesel offered in Ram 2500/3500 pickups, so it defined the brand's heavy-duty position. Lower-rated versions were used in cab-and-chassis 3500 trucks. How its ratings stacked up against Ford and GM diesels in each model year is not yet sourced.
Rebuild Potential
Tier BEditorial opinion.
The 6.7L Cummins has excellent parts, community, and aftermarket support and a good reputation, and its failure points are well known. The early years carry a head gasket weakness and heavier EGR and filter loads, so the 2013-2018 trucks are usually preferred. The emissions systems add cost, which keeps it at tier B.
Best year ranges
- 2013-2018: Owners commonly call these years the balance of power and reliability; the early 2007.5-2012 engines had a head-gasket weakness that was updated around 2013 (secondary sources).
Known weak points
The turbo actuator wears or sticks with soot, common after about 100,000 miles.
Common fix: Service or replace the actuator and clean the turbo.
Cracked exhaust manifolds are a leading reason for shop visits.
Common fix: Replace with an OEM-style manifold and hardware.
Early 2007.5-2012 engines have a head gasket weakness, especially on hard-worked or tuned trucks.
Common fix: Replace with updated gaskets and torque per specification.
The EGR system and particulate filter clog with carbon, especially on engines built before 2013.
Common fix: Service or replace EGR and filter components with compliant parts.
Common upgrade categories
- Turbo actuator and manifold service
- Updated head gaskets
- EGR and particulate filter service with compliant parts
- Cooling and transmission upgrades
- Bolt-on intake and exhaust within local legal limits
This engine is emissions-equipped (EGR, particulate filter and, from 2011 on some engines, DEF/SCR). Keep the emissions equipment the truck was built with; repair or replace it with compliant parts. Removing or defeating it on a vehicle originally equipped with it is illegal under federal law. Rules vary by state (for example California/CARB), so check local law and model-year requirements before modifying.
Sources
- Cummins B Series engine (Wikipedia) (accessed 2026-09-18)
- Ram Heavy Duty (Wikipedia) (accessed 2026-09-18)