M 25 C

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The M 25 C, part of the MaK long-stroke engine generation, is based on the proven design characteristics of the M 20 C, M 32 C and M 43 C engine series. When developing this new engine generation, the objective was to achieve a high benefit level for the customer. In all design and development considerations, therefore, three criteria had the highest priority: reliability, economy and environmental compatibility. Other points of significance in the engine's design and development work were ease of maintenance, long maintenance intervals, long component life and ease of installation.

Power Rating

  • Power Range 1740-3000 kW 1740-3000 kW

Engine Specifications

  • Speed Range 720-750 rpm 720-750 rpm
  • Emissions IMO II IMO II
  • Aspiration Turbocharged Turbocharged
  • Bore 10.0 in 255.0 mm
  • Stroke 15.78 in 400.0 mm
  • Rotation from Flywheel End Counterclockwise/Clockwise Counterclockwise/Clockwise
  • Configuration Inline 6,8,9 Cylinder Inline 6,8,9 Cylinder
  • Swept Volume 1244.89 in³ 20.4 l/cyl

Dimensions & Weights

  • Minimum Dry Weight 46738.0 lb 21.2 ton (US)
  • Minimum Length 210.4 in 5345.0 mm
  • Maximum Length 264.5 in 6719.0 mm
  • Minimum Height 133.3 in 3387.0 mm
  • Maximum Height 148.4 in 3769.0 mm
  • Minimum Width 88.1 in 2237.0 mm
  • Maximum Width 90.2 in 2291.0 mm

Intelligent simplicity

This MaK design principles is most clearly reflected in the reduction in the number of components. About 40 % of parts have been dispended. It has resulted in a marked gain in operational reliability and a reduction in operating costs.

Reliable energy supply

The complete diesel engine is notable for its ease of installation, reliable operation, ease of maintenance and good component accessibility.

Low fuel consumption

Ready for installation

In addition to many outstanding technical features, the long-stroke M 25 C engine is also easy to install and provides good maintenance access to all components.

Long maintenance intervals and component life

Complete propulsion system

The supply of complete propulsion systems is a market requirement which is becoming increasingly important.

Robust and simple

Reduction in the number of components

Environmentally-friendly due to low NOx and CO2 emissions

System responsibility and supply from a single source, accurately matched interfaces and coordinated delivery data control

M 25 C Standard Equipment

Air Inlet System

  • Air intake silencer / filter

Control System

  • Load sharing unit (for multiple engine plant only)
  • Protection panel (emergency stop, override, reset push buttons)
  • Protection system
  • Serial link interface (MODbus / canbus)
  • Speed governor
  • Start / stop panel

Cooling System

  • 2-stage charge air cooler
  • Electronic cooling water preheater
  • HT cooling water pump (engine driven)

Exhaust System

  • Exhaust gas expansion joint
  • Exhaust gas insulated manifolds
  • Turbocharger at flywheel end

Fuel System

  • Fuel circulating pump (attached / MGO/MDO only)
  • Fuel indicator filter
  • Fuel pressure valve (attached / MGO/MDO only)


  • Control push buttons and lamps
  • Emergency stop lever
  • Local control panel
  • Pressure and temperature indicator

Lube System

  • Dry sump
  • Lube oil plate cooler (separate)
  • Lube oil pump (engine driven)
  • Lube oil self-cleaning filter
  • Pressure regulating valve

Mounting System

  • High flexible coupling
  • Rigid mounting

Starting System

  • Electrical barring device
  • Starting air valve


  • Lifting device (rental)
  • Torsional Vibration Calculation (TVC)

M 25 C Optional Equipment

Air Inlet System

  • Air inlet shut-off valve
  • Air intake transition piece
  • Expansion joint
  • Silencer / filter

Control System

  • Electronic speed governor
  • Engine alarm system
  • Remote control system
  • Remote indicators (start air pressure, engine speed, etc.)
  • Starter for electric driven pumps
  • 24 DC UPS

Cooling System

  • FW/SW plate cooler
  • HT cooling water pump (electric driven)
  • LT cooling water pump (electric driven)
  • Sea water cooling pump (electric driven)
  • Steam / thermal oil cooling water preheater
  • Temperature control valve

Exhaust System

  • Silencer (with or without spark arrester)
  • Turbocharger at counter-flywheel side

Fuel System

  • Fuel oil cooler
  • HFO final preheater
  • HFO pressure regulating valve
  • HFO self-cleaning automatic filter
  • HFO supply and booster pumps (electrical driven)
  • HFO treatment and supply modules
  • HFO viscosity control device
  • Mixing tank

Lube System

  • Lube oil centrifuge
  • Lube oil pump (electrical driven)
  • Lube oil treatment and combined modules
  • Pre-lubricating oil pump (electrical driven)
  • Temperature control valve
  • Wet sump with dip stick

Mounting System

  • Flexible pipe connections
  • Resilient mounting

Starting System

  • Starting air compressor
  • Starting air receiver


  • Cat Propulsion Systems
  • Engine PTO coupling
  • PTO alternator
  • PTO shaft on counter-flywheel side
  • Reduction gear
  • Reduction gear PTO coupling

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