Caterpillar C9 (medium-duty + bus)
8.80L Inline-6 turbo diesel • Caterpillar
About the Caterpillar C9 (medium-duty + bus)
The Caterpillar C9 ACERT is Cat's 8.8L medium-duty engine, produced 2003-2010 for Class 6-8 medium-duty trucks, buses, and motor homes. Like the C13 and C15, the C9 used Cat's ACERT emissions strategy and was discontinued in 2010 when Cat exited on-highway. The C9 powered many city transit buses, school buses, and medium-duty vocational trucks during its production run. Used C9s remain in service in bus fleets and Class 6-7 vocational applications.
Overview
The Caterpillar C9 ACERT is Cat's 8.8L medium-duty engine, produced 2003-2010 for Class 6-8 medium-duty trucks, buses, and motor homes. Like the C13 and C15, the C9 used Cat's ACERT emissions strategy and was discontinued in 2010 when Cat exited on-highway. The C9 powered many city transit buses, school buses, and medium-duty vocational trucks during its production run. Used C9s remain in service in bus fleets and Class 6-7 vocational applications.
Specifications
- Manufacturer
- Caterpillar
- Displacement
- 8.80 liters
- Configuration
- Inline-6 turbo diesel
- Fuel type
- Diesel
- Horsepower
- 250–400 hp
- Torque
- 750–1250 lb-ft
- Production years
- 2003–2010
- Truck classes
- Class 6-8
- Applications
- Bus, medium-duty truck, vocational, RV (legacy)
Design and engineering
8.8L inline-6 with wet-sleeve liners. Cat ACERT emissions system. Designed for high-cycle medium-duty applications.
Generations and emissions eras
Reliability and longevity
Generally reliable — bus/RV applications often see 500K-800K miles before overhaul. Stop-and-go duty cycle is harder on the DPF system than highway use.
Common problems
DPF face plugging in stop-and-go bus/delivery service. EGR cooler cracking on ACERT.
Pros and cons
✓ Pros
- • Cat medium-duty heritage
- • Strong parts availability
- • Acceptable reliability
⚠ Cons
- • Production ended 2010
- • DPF issues in transit bus duty
- • Outshadowed by Cummins ISL in same segment