PACCAR engines
PACCAR’s truck-engine range includes heavy-duty MX and medium-duty PX families. The letters and suffix identify a starting point, but the engine serial number, emissions generation and truck build determine the applicable rating and service information. Compare engines within a complete chassis specification. A fuel-efficiency claim or a maximum output figure cannot establish a particular truck’s operating cost or its suitability for every application.
Compare the model families
MX-13
Heavy-duty diesel enginePACCAR identifies its EPA MX-13 as a 12.9 L engine. The MX-13 designation spans model years, so the current product page should be read alongside the serial-number and year-specific documentation for a used truck. Its heavy-duty role differs from the PX medium-duty family.
MX-11
Heavy-duty MX-family dieselMX-11 is a PACCAR heavy-duty engine designation separate from MX-13. PACCAR provides an MX-11 operator’s manual for the 2024 generation. Use the manual and specification appropriate to the individual engine rather than transferring ratings from a different MX model or market.
PX-9
Medium-duty PX-family enginePACCAR lists PX-9 in its medium-duty engine range, separately from PX-7 and the heavy-duty MX engines. The manufacturer’s catalogue publishes a range of ratings, so the PX-9 label should not be treated as one fixed horsepower or torque specification.
PX-7
Medium-duty PX-family engineThe PX-7 is PACCAR’s smaller PX-family medium-duty engine offering. Its product page describes electronic engine control and a variable-geometry turbocharger. Confirm the installed generation and rating rather than assuming every PX-7 shares all details of a current specification.
Bring the exact specification.
The family name helps organize your search. The build sheet, serial number and relevant manufacturer documentation identify what is installed. Compare like-for-like applications and request evidence for cost or performance claims.
PACCAR manufacturer reference ↗Independent editorial resource. Brand names identify equipment; they do not imply a partnership or endorsement.