Is the 6.7 liter Cummins a good engine?
The 6.7-liter Cummins is generally regarded as a strong, durable diesel with ample torque for towing and heavy-duty work. With regular maintenance, it remains a reliable choice for Ram 2500/3500 trucks. Like other modern diesels, it requires attention to emissions systems and service intervals to avoid costly repairs.
Overview of the 6.7L Cummins
The 6.7L Cummins inline-6 diesel has powered Ram heavy-duty pickups since 2007 and has evolved through multiple generations. It employs a high-pressure common-rail fuel system and a turbocharger to deliver substantial torque for towing and heavy workloads. Across model years, Cummins offered two main output configurations to suit different applications: a standard-output version and a high-output (HO) variant. Reliability is well-regarded, but owners should be mindful of emissions-related components and maintenance needs that can affect long-term ownership costs.
Strengths and capabilities
Two power outputs are common across generations, giving buyers options for balance between daily drivability and maximum towing power. Here are the core strengths that buyers often cite.
Two power outputs
- Standard-output configuration: typically around 370–385 horsepower and about 850–860 lb-ft of torque, suited for everyday driving and moderate towing.
- High-output configuration: typically around 420–430 horsepower and about 1,000 lb-ft of torque, designed for heavy payloads and maximum towing capability.
These power levels vary slightly by model year and emission package, so exact figures should be checked for a given vehicle. The engine’s torque and reliability have made it a staple for fleet and enthusiast use alike.
Common concerns and how to mitigate them
Like any modern diesel, the 6.7L Cummins has potential reliability hot spots and maintenance considerations. Being aware of these can help mitigate costly failures and downtime.
- Emissions equipment and cooling: EGR systems and the engine’s cooling network (including EGR cooler) can suffer failures, especially in high-heat or short-trip driving. Regular inspection and cooling system maintenance help prevent leaks and overheating.
- Diesel particulate filter (DPF) and regeneration: proper driving patterns (long highway drives to complete regen cycles) help prevent clogging and frequent limp-mode scenarios that can occur with lots of city driving.
- High-pressure fuel system components: the high-pressure fuel pump and related rails/injectors require clean fuel and proper maintenance. Neglect can lead to performance issues or costly repairs.
- Turbo and intake components: wastegate and turbocharger wear can occur with age, and dirty intake cores can reduce efficiency and power.
- Maintenance costs: diesel maintenance and replacement parts can be more expensive than gasoline-powered equivalents, so budgeting for higher service costs is prudent.
With careful maintenance and timely attention to emissions-related components, many owners report long, trouble-free service lives. Always verify a used engine’s maintenance history and consider a pre-purchase inspection, especially for older units or those with heavy towing histories.
Maintenance and ownership tips
Maintaining a 6.7L Cummins in good shape requires diligence, especially around oil, cooling, and emissions systems. The following steps help maximize reliability and lifespan.
- Follow the OEM maintenance schedule for oil changes, filters, and fluids, using the recommended synthetic oil and quality filters. Diesel engines typically benefit from scheduled service to keep injector and pump health optimal.
- Maintain coolant quality and monitor EGR cooling components; replace any leaking or failing EGR coolers promptly to prevent overheating and downstream damage.
- Use high-quality diesel fuel and consider fuel system cleaning intervals as recommended by the manufacturer or a trusted shop, to protect injectors and the high-pressure pump.
- Address any exhaust or emissions-related warning lights quickly; neglect can lead to failed regenerations, DPF issues, or reduced performance.
- Inspect the turbocharger, charge air pipes, and intake for leaks or cracks; address any boost leaks that can reduce power and efficiency.
- Monitor oil consumption and keep up with oil and filter changes; diesels can consume more oil as engines wear, so early detection is key.
- Prevent overheating by maintaining the cooling system, including the radiator, thermostat, water pump, and hoses, especially if you tow heavy loads or live in hot climates.
- For used trucks, review service records for EGR cooler replacement, DPF service history, and turbo/charge-air work; the absence of preventive maintenance can signal higher risk of costly repairs.
By sticking to maintenance intervals, using quality parts, and addressing issues promptly, owners can expect solid reliability from the 6.7L Cummins across its lifecycle.
Summary
Overall, the 6.7-liter Cummins is a well-regarded engine in the heavy-duty segment, offering strong torque, capable towing performance, and a durable design. It excels when properly maintained and operated within its intended application. Pros include robust low-end torque, widely available service and parts, and the option of a high-output tune for heavier workloads. Potential drawbacks center on emissions-related components and higher maintenance costs common to modern diesels. For buyers evaluating a Ram 2500/3500 or a used example, a thorough pre-purchase inspection and a solid maintenance history are key to ensuring long-term satisfaction.
