Machinery & Truck PartsThe Cummins ISB 6.7 is a 6.7-liter inline-six diesel introduced for 2007-era medium-duty and vocational applications. It uses high-pressure common-rail injection and was offered in multiple horsepower, torque, emissions, and accessory configurations, so an engine serial number and CPL are essential when matching a replacement. Machinery and Truck Parts stocks tested used Cummins ISB 6.7 engines, each identified by stock number and backed by warranty coverage. Call (800) 696-5459 with your truck and engine information for fitment help and a freight quote.
Cummins ISB 6.7L Engine Specifications
| Displacement | 6.7 L (408 cu in) |
| Configuration | Inline-6, 4-stroke turbodiesel |
| Bore x Stroke | 107 mm x 124 mm (4.21 in x 4.88 in) |
| Aspiration | Turbocharged and charge-air cooled |
| Fuel system | High-pressure common rail |
| Horsepower | Typical medium-duty ratings about 200 to 325 hp |
| Peak torque | Typical medium-duty ratings about 520 to 750 lb-ft |
| Governed speed | Commonly about 2,600 rpm |
| Emissions equipment | Varies by year; may include cooled EGR, DOC, DPF, and later SCR |
| Production era | 2007 and later |
| Predecessor | Cummins ISB 5.9L |
What Trucks and Equipment Use the Cummins ISB 6.7
The Cummins ISB 6.7 is widely used in Class 5 through Class 7 medium-duty trucks, school and shuttle buses, delivery and box trucks, utility vehicles, tow trucks, motorhomes, and selected vocational equipment. Common chassis applications include Freightliner, International, Kenworth, Peterbilt, Blue Bird, Thomas Built Buses, and other OEM installations. Ratings, electronics, aftertreatment, oil pans, mounts, and accessories vary by chassis and duty cycle, so confirm the engine serial number, CPL, ECM calibration, and emissions configuration.
Cummins ISB 6.7L vs. ISB 5.9L vs. ISC 8.3L
The ISB 6.7L succeeded the Cummins ISB 5.9L with more displacement, higher typical torque, common-rail injection, and newer emissions systems. The Cummins ISC 8.3L is a larger wet-liner engine intended for heavier vocational work and higher torque requirements. These families overlap in some chassis, but they are not automatic substitutes because electronics, mounts, flywheel housings, cooling, accessories, and emissions hardware differ.
Common Cummins ISB 6.7 Problems and What to Check When Buying Used
Confirm the engine serial number, CPL, model year, and aftertreatment generation first. Review cold-start behavior, hot oil pressure, blow-by, coolant condition, fault history, rail-pressure information, injector balance, turbocharger operation, and visible oil, fuel, or coolant leaks. On emissions-equipped engines, inspect the EGR system, variable-geometry turbo and actuator, crankcase ventilation, DOC, DPF, sensors, and SCR components where applicable. Verify which ECM, wiring harness, fan hub, air compressor, flywheel housing, oil pan, and accessory brackets are included.
Cummins ISB 6.7 Engines In Stock
Cummins ISB 6.7 Engine FAQ
What size engine is the Cummins ISB 6.7?
The Cummins ISB 6.7 is a 6.7-liter (408-cubic-inch) inline-six diesel with a 107 mm bore and 124 mm stroke.
How much horsepower does a Cummins ISB 6.7 make?
Medium-duty ratings commonly range from about 200 to 325 horsepower, depending on model year, calibration, emissions configuration, and application.
How much torque does a Cummins ISB 6.7 produce?
Typical medium-duty ratings are roughly 520 to 750 lb-ft, although the exact torque depends on the CPL and calibration.
What trucks use the Cummins ISB 6.7?
The ISB 6.7 is used in many Class 5 through Class 7 Freightliner, International, Kenworth, Peterbilt, school bus, shuttle bus, delivery, utility, tow-truck, and motorhome applications.
What is the difference between the Cummins ISB 5.9 and ISB 6.7?
The ISB 6.7 has more displacement, higher typical torque, common-rail injection, and newer emissions equipment. Electronics, accessories, and chassis interfaces vary, so it is not automatically a direct replacement for a 5.9.
Does the Cummins ISB 6.7 have a DPF?
Most 2007-and-later on-highway versions use a diesel oxidation catalyst and diesel particulate filter. Later versions may also use SCR and diesel exhaust fluid. Confirm the exact emissions year and configuration.
What should I check before buying a used ISB 6.7?
Confirm the serial number, CPL, horsepower rating, emissions generation, ECM calibration, turbo and aftertreatment configuration, mounts, flywheel housing, oil pan, included accessories, test results, and warranty terms.
How do I order a Cummins ISB 6.7 engine?
Choose an in-stock engine above and call (800) 696-5459 with its stock number, your truck year, make, model, engine serial number or CPL, and delivery ZIP code.