Cat® C12 Diesel Marine Propulsion Engines, with ratings of 340-490 bhp (254-366 bkW) at 1800-2300 rpm, meet IMO II emission standards with the exception of the 497 mhp (490 bhp) rating at 2300 rpm which meets IMO I emissions standards. The C12 takes full advantage of the electronically controlled unit injection fuel system, resulting in an environmentally friendly engine with outstanding performance and fuel economy. There is also a wide range of optional equipment available to meet the needs of your marine commercial or pleasure craft application.

Power Rating
Power Range 340-490 bhp (254-366 bkW)

Engine Specifications
Speed Range 1800-2300 rpm
Emissions IMO I, IMO II
Aspiration TA
Bore 5.1 in
Stroke 5.9 in
Displacement 732 in³
Rotation from Flywheel End Counterclockwise
Configuration In-line 6, 4-Stroke-Cycle Diesel

Dimensions & Weights
Dry Weight 2588 lb
Height 39.5 in
Length 62 in
Width 38.1 in

ADEM III Control System

More control inputs and outputs, capacity for additional features, additional monitoring capabilities, expansion capability for future enhancements

Most Advanced Electronic Control System

Adjustment free control of engine speed, customer defined operating characteristics, protection and warning system, optional display systems available

Future Enhancement Capability

The electronic control system has additional capacity for future enhancements to ensure a long useful engine life.

Redesigned Exhaust Manifold

Provides a smoother passage for improved exhaust gas flow to the turbocharger which leads to more usable energy and lower exhaust temperatures.

Easy Replacement for 3196

The C12 has the same physical size, same footprint, and the same connection points as the 3196 engine as well the same optional attachments.

Optional Monitoring System

Caterpillar offers several “plug and play” monitoring systems which display everything from the basic engine operating parameters to engine load factor and trip totals. Ask your local Caterpillar dealer for additional information on our Marine Power Display (MPD), Marine Analog Power Display (MAPD), and our Engine Vision Display (EVD).

Product Support

Trained technicians at over 1800 authorized service locations worldwide support Caterpillar products. Use our Internet Dealer Locator www.cat.com to identify the Caterpillar dealer location nearest to you.


C-12 Marine Propulsion engines used in commercial applications are covered for 12 months from the date of delivery to the end user. Engines used in non-revenue producing pleasure craft applications are covered for 24 months, unlimited hours, from the date of delivery. Concurrently, specific engine components are covered for 60 months, unlimited hours, from the date of delivery to the end user.

Extended Service Coverage (ESC)

Optional engine protection coverage for up to 60 months from date of delivery may be purchased through your local Caterpillar dealer.

Standard Equipment

Air Inlet System
  • Aftercooler - sea water; corrosion resistant, Air Cleaner/Fumes Disposal (closed system), Turbocharger, Jacket Water Cooled
Control System
  • Electronic governing, Cold mode start strategy, Power compensation for fuel temperature, Programmable low idle, Electronic diagnostics and fault logging, Engine and transmission monitoring (speed, temperature, pressure), Fuel/air ratio control, Emergency
Cooling System
  • Thermostat and housing, Jacket water pump; gear driven, Sea water pump; rubber impeller; self-priming; gear-driven, Integral heat exhanger/expansion tank; removable tube bundle; replaceable copper-nickel tubes, Keel cooling - combined circuit (includes pi
Exhaust System
  • Watercooled Manifold & Turbocharger
Flywheels & Flywheel Housings
  • Flywheel; SAE No. 1; 113 teeth, Flywheel housing; SAE No. 1 (10 degree slant pad), SAE standard rotation
Fuel System
  • Fuel filer; RH service on Port; LH service on Starboard, Fuel transfer pump, Fuel priming pump, Flexible fuel lines
  • Service meter, electric
Lube System
  • Crankcase breather, Oil cooler, Oil filter; spin-on; RH service on Port; LH service on Starboard, Oil filler, Dipstick; RH service on Port; LH service on Starboard, Oil pump; gear driven
Mounting System
  • Front support
Power Take-Offs
  • Hydraulic pump drive; SAE A; 11 tooth spline, 57 ft-lbs max torque; counterclockwise as viewed from the rear of hte engine looking into the pump drive and turns 1.41 x engine speed, Crankshaft pulley; 345 mm (13.6 in) single groove; 15.88 mm (.63in) width
Protection System
  • Shutdown; electronic; 12 or 24 volt; energized to run
  • Vibration damper, Lifting eyes, RH or LH service options, Literature, Variable engine wiring, Upper rear-facing customer wiring connector and ECAP connection, Electronic installation kit (connectors, pins, sockets)

Optional Equipment

Air Inlet System
  • Low Profile Air Inlet Line, Shield (Air Inlet Line)
Charging System
  • Charging Alternators, Voltmeter Guages, Voltmeter Guage Mounting, Alternator Mounting Group
Cooling System
  • Sea Water Pump, Coolant Recovery Tank, Flange Kit
Exhaust System
  • Flexible Fitting, Elbow, Dry Elbow, Watercooled Elbow, Exhaust Connection, Exhaust Outlet Pipe, EXH Outlet Flange, Rain Cap, Muffler
Fuel System
  • Fuel Cooler, Fuel Connections, Primary Fuel Filter, Primary Fuel/Water Separator
  • OEM Wiring Harness, Engine to Engine Harness, Digital Tachometer, Tachometer Mounting, Magnetic Pickup, RH 4 Hole Instrument Panel, LH 4 Hole Instrument, Marine Power Display System, Marine Power Display Unit (for additional monitoring stations), Marine P
Lube System
  • Manual sump pump, Transmission oil cooler
Mounting System
  • Vibration Isolators
Power Take-Offs
  • Crankshaft Pulley, Front Stub Shaft, Front Stub Shaft & Pulley
Starting System
  • Air Pressure Regulator, Air Start Silencer, Start Switch, Jacket Water Heater, Battery sets (24 volt - dry)
  • Wiring Harness Removal, Belt Guard - Alternator, Belt Guard - Alternator Pulley, Filter Cover Kit
  • Overseas Preservation, Engine Protective Cover, Storage Preservation, Export Packing



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