PACCAR MX-13 Engine for Sale | 12.9L Inline-6 Class 8 Truck Diesel | Direct Fit Kenworth T680, Peterbilt 579 and Related Chassis

Used PACCAR MX-13 Engine For Sale

The PACCAR MX-13 engine is a testament to robust engineering and exceptional performance in the commercial trucking industry. The durable and fuel-efficient nature of this PACCAR MX-13 engine for sale at our store makes it a preferred choice for Kenworth and Peterbilt truck operators who want proven PACCAR power for their Class 8 long-haul and vocational applications.

The PACCAR MX-13 Heritage

The PACCAR MX-13 is a 12.9-liter Inline-6 diesel engine, the flagship engine product from PACCAR Inc., parent company of Kenworth Truck Company, Peterbilt Motors, and European truck manufacturer DAF Trucks. The MX-13 has its roots in the DAF MX-13 engine introduced in European DAF trucks in 2005, after PACCAR’s acquisition of DAF in 1996 enabled global engine platform sharing.

The MX-13 was launched in North American Kenworth and Peterbilt trucks in 2010 (2011 model year), produced at PACCAR’s brand-new engine manufacturing facility in Columbus, Mississippi, which opened in 2010 specifically to produce the MX-13 for the North American market.

The MX-13 has gone through multiple generations to address tightening emissions and efficiency requirements:

• 2011 to 2017 MX-13: Original North American production (EPA10 / GHG14 emissions)

• 2017+ MX-13: GHG17 emissions with engine downspeeding optimizations for improved fuel economy at highway cruise

• Current MX-13: GHG21+ emissions with continuing efficiency improvements

• DAF MX-13: European market equivalent, slightly different calibrations and accessories

The MX-13 also has a smaller sibling, the PACCAR MX-11 (10.8 liter Inline-6), for lighter-duty Class 8 and Class 7 applications.

Condition of PACCAR MX-13 Engines

Our inventory includes used PACCAR MX-13 engines that are meticulously inspected and fully tested. The engines are categorized based on their condition:

• Used Engines: These engines are thoroughly checked for wear, with all 6 cylinders compression tested, high-pressure common rail injectors inspected, VGT turbocharger condition assessed, and emissions aftertreatment hardware (DPF / SCR / DEF / EGR cooler) condition documented before shipping.

Key Features of PACCAR MX-13 Engine

The PACCAR MX-13 engine is renowned for its advanced features:

• High-Pressure Common Rail Injection: The MX-13 uses high-pressure common rail direct injection with injection pressures up to approximately 2,500 bar (about 36,250 psi), delivering precisely-metered fuel for optimal combustion, better fuel efficiency, and reduced engine noise compared to mechanical injection systems.

• Variable Geometry Turbocharger (VGT): The MX-13’s VGT optimizes turbocharger performance across the engine’s full operating range by varying the angle of the turbine inlet vanes, controlling boost pressure and exhaust energy recovery for both low-rpm response and high-rpm power.

• Compacted Graphite Iron (CGI) Block: The MX-13 cylinder block is cast from Compacted Graphite Iron (CGI), a material that is approximately 75% stronger and 40% stiffer than conventional gray cast iron while being lighter. CGI allows the MX-13 to handle higher peak cylinder pressures (essential for high-efficiency combustion) without weight penalty.

• Exhaust Gas Recirculation (EGR): Cooled EGR reduces NOx formation by recirculating a metered portion of exhaust gas back into the engine intake, complementing the SCR aftertreatment system for full emissions compliance.

• Integrated PACCAR Engine Brake: The MX-13 features an integrated compression-release engine brake (similar in operation to a Jacobs Engine Brake), providing significant downhill retarding power to reduce wear on the service brakes and enable safer mountain descents with heavy Class 8 loads.

• DOHC 4-Valve Cylinder Heads: Double overhead camshaft (DOHC) cylinder heads with 4 valves per cylinder (2 intake, 2 exhaust per cylinder, 24 valves total) optimize airflow into and out of the combustion chambers, enabling better volumetric efficiency, lower pumping losses, and improved fuel economy at cruise.

• Advanced Cooling System: A high-efficiency radiator and coolant system maintains optimal operating temperatures even under maximum load on mountain grades or in high-ambient-temperature conditions.

• Oil Management System: Enhanced oil filtration and cooling extends oil service intervals (typically 50,000 to 75,000 miles in linehaul service with PACCAR oil sampling program) and contributes to overall engine longevity.

• Electronic Control Module (ECM): The MX-13 ECM monitors and manages engine parameters in real-time, providing precise control of fuel injection, turbocharger boost, EGR flow, and aftertreatment dosing, with full integration into the Kenworth or Peterbilt vehicle control network for diagnostics and driver information.

• B10 Design Life of 1,000,000 Miles: PACCAR engineers the MX-13 with a B10 design life of 1,000,000 miles, meaning only 10% of engines reach end-of-life by one million miles of service, making the MX-13 one of the most durable Class 8 truck engines on the market.

The PACCAR MX-13 Engine Fits

Kenworth Trucks:

• Kenworth T680 (the dominant MX-13 application, Kenworth’s flagship aerodynamic long-haul truck; the T680 with MX-13 is one of the most-sold combinations in the Class 8 market)

• Kenworth T880 (Kenworth’s vocational and heavy-haul chassis with MX-13 power option)

• Kenworth W990 (Kenworth’s premium conventional long-hood truck with MX-13 option)

• Kenworth T370 (medium-heavy Class 7 / 8 vocational chassis)

• Kenworth T660 (legacy aerodynamic chassis preceding the T680, MX-13 available in later production)

Peterbilt Trucks:

• Peterbilt 579 (the dominant Peterbilt MX-13 application, Peterbilt’s flagship aerodynamic long-haul truck; the 579 with MX-13 mirrors the Kenworth T680 in Peterbilt branding)

• Peterbilt 567 (Peterbilt’s vocational and severe-duty chassis)

• Peterbilt 389 (Peterbilt’s premium long-hood conventional, the iconic “owner-operator” truck, MX-13 option)

• Peterbilt 520 (refuse and severe-duty cab-over chassis)

• Peterbilt 365 (vocational and heavy-haul chassis)

DAF Trucks (European market, sold as DAF MX-13):

• DAF XF (the European flagship long-haul truck)

• DAF CF (DAF’s distribution and regional-haul chassis)

• DAF LF (DAF’s lighter-duty chassis; lighter MX-11 also available)

Common Transmission Pairings With MX-13

The MX-13 is commonly paired with:

• Eaton Fuller manual transmissions (10-speed, 13-speed, and 18-speed Fuller Roadranger)

• Eaton Fuller UltraShift PLUS automated manual transmission

• PACCAR TX-12 automated manual transmission (PACCAR’s own AMT, increasingly popular in current production)

• Allison automatic transmissions (vocational chassis applications)

Condition

Our used PACCAR MX-13 engines are well-maintained and in working condition. Each engine has been previously used in Class 8 commercial trucking service, with full documentation of donor truck application, mileage, and service history where available.

Signs You Need a Replacement PACCAR MX-13

• Loss of compression on one or more cylinders

• High-pressure common rail injector failure (a documented MX-13 service item at high mileage)

• VGT turbocharger failure (vane sticking, bearing wear, boost loss)

• EGR cooler failure (coolant in oil, coolant in EGR pipe, white exhaust smoke)

• DPF aftertreatment failure (excessive regeneration cycles, derate conditions)

• SCR / DEF system failure (DEF doser issues, NOx sensor failure)

• Connecting rod or main bearing knock under load

• Cylinder head crack symptoms (coolant in oil, white smoke, overheating)

• Donor Kenworth or Peterbilt totaled or retired and the MX-13 is being moved to another chassis

• Fleet repower project requiring proven PACCAR MX-13 reliability for owner-operator or small-fleet operations

Common MX-13 Maintenance Considerations

• Oil service: Use PACCAR Specification 1100098 Genuine PACCAR Oil (or compatible API CK-4 spec heavy-duty diesel engine oil). Service intervals 50,000 to 75,000 miles with PACCAR oil sampling program.

• Fuel filters: CRITICAL for high-pressure common rail injector longevity. Change fuel filters at every oil service. Contaminated fuel is the leading cause of common rail injector failure.

• DEF service: Diesel Exhaust Fluid is consumed at approximately 2-3% of diesel fuel rate. Monitor DEF level and quality. Use only API-certified DEF.

• DPF regeneration: Active and passive DPF regeneration occurs automatically. Avoid extended low-load operation (idling, short trips) that prevents passive regen.

• Coolant service: Use PACCAR-approved heavy-duty extended life coolant. Service every 600,000 miles or 6 years with proper SCA (Supplemental Coolant Additive) maintenance.

• Valve adjustment: Periodic valve clearance check per PACCAR service interval (typically at major service points).

• Engine brake service: Periodic inspection of PACCAR engine brake solenoids and oil supply.

FAQs

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