Kenworth T680 with PACCAR MX-13 Engine in Long-Haul Operations

[MikePhua]

Kenworth’s T680 and the Rise of Integrated Efficiency
The Kenworth T680, introduced in 2012, marked a shift toward aerodynamic design and fuel-efficient powertrains in the Class 8 truck market. Built for long-haul and regional applications, the T680 features a sloped hood, optimized fairings, and a spacious sleeper cab. It quickly became a favorite among owner-operators and fleets seeking lower operating costs and improved driver comfort.
Paired with the PACCAR MX-13 engine, the T680 offers a vertically integrated solution—Kenworth and PACCAR under one umbrella—streamlining diagnostics, parts sourcing, and service protocols. The MX-13, developed in Europe by DAF and adapted for North American emissions standards, delivers up to 510 horsepower and 1,850 lb-ft of torque, making it suitable for both flatland and moderate-grade hauling.
MX-13 Engine Characteristics and Common Issues
The MX-13 is a 12.9-liter inline-six diesel engine featuring:

• High-pressure common rail fuel injection
  
• Variable geometry turbocharger
  
• Exhaust gas recirculation (EGR)
  
• Diesel particulate filter (DPF) and selective catalytic reduction (SCR)
  

While praised for its quiet operation and fuel economy, the MX-13 has faced criticism for emissions-related reliability. Common issues include:

• DPF clogging and regeneration failures
  
• EGR cooler leaks
  
• Turbo actuator malfunctions
  
• Sensor faults triggering derate conditions
  

One operator reported that his T680 with MX-13 ran well for 200,000 miles before experiencing intermittent power loss. After multiple dealer visits, the culprit was a faulty NOx sensor that misreported emissions levels, causing the engine to derate. Replacing the sensor restored full power, but the downtime highlighted the complexity of modern emissions systems.
Transmission Pairing and Drivability
Most T680s with MX-13 engines are paired with Eaton Fuller automated transmissions or PACCAR’s own 12-speed automated gearbox. These setups offer:

• Smooth shifting under load
  
• Optimized gear selection for fuel economy
  
• Hill start assist and creep mode
  

However, some drivers prefer manual transmissions for better control in mountainous terrain or when hauling irregular loads. The MX-13’s torque curve supports both configurations, but automated transmissions may require software updates to maintain shift quality.
Fuel Economy and Maintenance Intervals
Operators report fuel economy ranging from 6.5 to 8.5 mpg depending on load, terrain, and driving style. The MX-13’s sweet spot lies between 1,200 and 1,500 rpm, where torque is abundant and fuel burn is minimized.
Recommended maintenance intervals include:

• Oil change: every 40,000 miles (with synthetic oil)
  
• Fuel filter replacement: every 20,000 miles
  
• Valve adjustment: every 250,000 miles
  
• DPF cleaning: every 300,000 miles or as needed
  

Using high-quality DEF and monitoring soot levels can extend DPF life and reduce regeneration frequency.
Cab Comfort and Driver Experience
The T680’s cab is designed for long-haul comfort:

• Quiet interior with triple-sealed doors
  
• Ergonomic dashboard and steering controls
  
• Optional 76-inch sleeper with workstation and bunk
  
• LED lighting and ample storage
  

Drivers appreciate the visibility, ride quality, and climate control. One fleet manager noted that driver retention improved after switching to T680s, citing reduced fatigue and better morale.
Resale Value and Fleet Economics
Kenworth trucks hold strong resale value due to brand reputation and parts availability. The MX-13, while less common than Cummins engines, benefits from PACCAR’s dealer network and integrated support.
For fleets:

• Lower fuel costs offset higher upfront price
  
• Extended warranty options reduce risk
  
• Telematics integration improves maintenance planning
  

Some fleets report total cost of ownership savings of 5–8% over five years compared to legacy models.
Recommendations for Buyers and Operators
When considering a T680 with MX-13:

• Verify service history and emissions system health
  
• Use OEM filters and fluids to maintain warranty
  
• Monitor fault codes with PACCAR diagnostic tools
  
• Train drivers on optimal RPM and shifting practices
  
• Consider extended warranties for emissions components
  

For owner-operators, the T680 offers a balance of comfort, efficiency, and brand prestige. For fleets, it delivers consistent performance and manageable maintenance when properly supported.
Conclusion
The Kenworth T680 with PACCAR MX-13 engine represents a modern approach to long-haul trucking—where aerodynamics, emissions compliance, and driver comfort converge. While emissions systems add complexity, proactive maintenance and informed operation can unlock the full potential of this integrated platform. In the world of freight, uptime and fuel economy are king—and the T680 aims to deliver both.