Kohler Engines. Relentless Power. Legendary Performance.

Kohler Diesel Air-Cooled



The diesel engine delivers the Performance Engineering standards you've come to expect from KOHLER. The direct injection system produces increased power and lower fuel consumption. Full pressure lubrication offers superior cooling and performance combined with full-flow oil filters for longer engine and component life. Air cooling, horizontal shaft, single-cylinder design, and a cast iron liner set the standard for power and engineering excellence all backed with a 3-year full warranty.


Fuel Type
18.8 Horizontal Twin Air Diesel Not Sold in North America

Durable, Long Life Design.

Aluminum crankcase with re-borable cast iron cylinder liner provides extra protection in tough environments while full-pressure lubrication with full-flow filter ensures continuous oil flow to critical parts, extending the engine life. Integral cooling fan contributes to longer engine life by reducing the operating temperature.

High Power Performance.

Direct injection delivers increased power and lower fuel consumption.


Reliability and Long Life Design.

  • Full pressure lubrication provides superior cooling and performance for longer component life.
  • Full-flow oil filters ensure longer engine life in tough environments.
  • Aluminum block with integrated re-borable cast-iron liner and feet so there's less weight, longer life.
  • Allows for lower vibration.
  • Direct injection for superior, more complete combustion produces increased power and lower fuel consumption.
Engine Uses

Engine Type:

Four-stroke, integral fan air cooling, aluminum alloy independent head, electric start, direction injection

Diesel KD425-2
J1940 Power hp(kW) 1 18.8 (14)
Displacement cu in (cc) 51.9 (851)
Bore in (mm) 3.3 (85)
Stroke in (mm) 3 (75)
Peak Torque lbs. ft (Nm) 31 (42)
Compression Ratio 19.0:1
Dry Weight lbs (kg) 138.9 (63)
Oil Capacity U.S. quarts (L) 1.9 (1.8)
Lubrication Full pressure w/full-flow filter
Dimensions L x W x H in 19.1 x 18.3 x 19.6
1 Power (hp) and Torque (lbs ft) specifications for Kohler general purpose engines are rated pursuant to Society of Automotive Engineers (SAE) J1940 based on gross output testing performed according to SAE J1995 without the air cleaner and muffler. Actual engine power and torque are lower and affected by accessories (air cleaner, exhaust, charging, cooling, fuel pump, etc.), application, engine speed, ambient operating conditions (temperature, humidity and altitude) and other factors. This J1940 / J1995 rating provides consistent measurement to customers who may want to control the intake and exhaust features of the engine. For more information, contact Kohler Co. Engine Engineering Department. Kohler Co. reserves the right to change product specifications, designs and standard equipment without notice and without incurring obligation.