OceanSphereENGINES

M 43 C

Main Engine 4-Stroke · Main Engines (4-Stroke)

Technical data from manufacturer or class sources · not yet verified by a person​​‍​⁠⁠⁠​⁠‌⁠⁠⁠⁠​​​‍‍‍
6 / 16Cylinders
430 mmBore
610 mmStroke
HFO/MDOMedium

Crew, engineers, and operators aboard large vessels depend on powerful and reliable medium-speed engines to keep their operations running smoothly. The Caterpillar MaK M 43 C is a prime example of this type of engine, designed for propulsion in the 5–9 MW class. This engine boasts a 6L-16V configuration with 430 mm bore and 610 mm stroke, capable of reaching speeds between 500 and 514 rpm. It's a 4-stroke turbocharged intercooled non-reversible engine with direct injection, fueled by either heavy fuel oil (HFO) or marine distillate oil (MDO). The M43C Series engine delivers approximately 700–760 kW per cylinder and features a nodular cast iron cylinder block, known for its improved wear resistance. The MaK M 43 C's turbocharger maintenance interval is set at 15,000 operating hours, requiring inspection and cleaning.

Specifications

Technical data.reference — unverified

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SFOC (Specific Fuel Oil Consumption)175–178 g/kWh (HFO optimized)
Lube Oil Consumption0.6 g/kWh standard; 0.3 g/kWh optional
Engine Type4-stroke turbocharged intercooled non-reversible with direct injection
Cylinder Block MaterialNodular cast iron (Kugelgraphitguss)
Turbocharger Maintenance Interval15,000 operating hours (inspection/cleaning)
Per-Cylinder Power Output~700–760 kW/cylinder
Engine Centre Distance3400 mm
Charge Air CoolerCast casing with 40% increased base area for turbocharger mounting
Speed (rpm)500/514
Service

Service notes.

What our service work and the manufacturer documentation say about keeping this model running.

Large medium-speed engine; maintain cylinder units, fuel equipment, bearings and turbochargers by Caterpillar MaK schedule.

Inspection

Inspector Detail ✓ verified

Common issues

  • Exhaust valve seat wear and burning, especially with HFO operation and poor fuel quality.
  • Fuel injector leakage or poor spray patterns leading to incomplete combustion and thermal stress.
  • Turbocharger fouling (compressor and turbine sides) reducing efficiency and increasing exhaust back pressure.
  • Bearing damage (main and connecting rod) due to contaminated lube oil, insufficient oil film, or misalignment.
  • Piston ring wear, breakage, or sticking, leading to increased lube oil consumption and blow-by.
  • Fuel pump element wear or sticking, affecting fuel delivery timing and quantity.
  • Cooling water system blockages or leaks, leading to localized overheating or corrosion.

Inspection checklist

  • Monitor exhaust gas temperatures per cylinder for deviations (indicative of combustion issues, valve condition, or injector problems).
  • Check cylinder indicator diagrams (if available) or perform compression tests to assess cylinder condition (liner wear, valve sealing).
  • Inspect fuel injection system for leaks, proper atomization (if visible), and fuel pump rack synchronization.
  • Visually inspect turbocharger for oil leaks, abnormal noises, and check boost pressure and exhaust gas temperatures before/after TC.
  • Perform regular lube oil analysis (spectroscopy, viscosity, TBN, water content) to monitor bearing health and oil contamination.
  • Check crankcase for abnormal noises, excessive blow-by, and ensure oil mist detector is functional.
  • Inspect cooling water system for leaks, proper pressure, and signs of corrosion or scaling in heat exchangers.
  • Examine engine mounting for signs of movement, loose bolts, or excessive vibration during operation.
  • Verify proper operation of all safety devices: overspeed trip, low lube oil pressure shutdown, high cooling water temperature shutdown.

Service intervals

Exhaust Valve Overhaul/Exchange8,000 - 12,000 hours
Fuel Injector Overhaul/Exchange3,000 - 6,000 hours
Piston Overhaul (inspection, ring renewal)16,000 - 24,000 hours
Main & Connecting Rod Bearing Inspection/Renewal24,000 - 32,000 hours
Turbocharger Minor Overhaul (cleaning, bearing inspection)8,000 - 12,000 hours
Turbocharger Major Overhaul (full strip-down, balancing)24,000 - 36,000 hours
Fuel Pump Overhaul8,000 - 12,000 hours
Cylinder Liner Inspection/Measurement16,000 - 24,000 hours

Typical wear limits

Cylinder Liner Wear (max ovality/taper)0.6 - 0.8 mm
Piston Ring Groove Wear (axial clearance increase)0.15 - 0.2 mm
Crankshaft Deflection (across adjacent main bearings)Max 0.05 mm
Exhaust Valve Seat Recession0.8 - 1.0 mm (depending on design)
Main/Connecting Rod Bearing Clearance (increase from new)0.25 - 0.35 mm
Turbocharger Rotor Axial PlayManufacturer specific, typically 0.1 - 0.2 mm
Fuel Pump Plunger/Barrel WearVisual inspection for scoring, loss of sealing

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

  • Complete exhaust valve units (or spindles/seats/rotators)
  • Fuel injectors (complete units or nozzles)
  • Piston rings (complete set for at least one cylinder)
  • Main and connecting rod bearing shells (one set each)
  • Fuel pump elements and delivery valves
  • Turbocharger bearing cartridge or complete rotor assembly
  • Various gaskets, O-rings, and seals for common maintenance tasks
  • Starting air valve and safety valve spares

Safety

  • High-pressure fuel lines: Risk of spray fires from leaks, especially with HFO.
  • Hot surfaces: Exhaust manifold, turbocharger, and cylinder heads pose severe burn risks.
  • Crankcase explosion: Ensure oil mist detector is operational and crankcase relief valves are clear.
  • Rotating machinery: Guarding must be in place for flywheel, turning gear, and turbocharger.
  • Heavy lifting: Components like cylinder heads, pistons, and turbochargers are heavy and require proper lifting gear and procedures.
  • Confined spaces: Entry into crankcase or exhaust gas casings requires permit-to-work and gas freeing procedures.

Class survey

Class surveyors will typically require crankshaft deflection readings, opening of at least one main bearing and one connecting rod bearing for inspection, and measurement of cylinder liner wear. They will verify the functionality of all engine safety devices (overspeed, low LO pressure, high CW temp, oil mist detector). Fuel system integrity, fire prevention arrangements, and exhaust gas system condition are also key. Review of engine maintenance records, lube oil analysis reports, and performance logs is mandatory to assess overall engine health and compliance with planned maintenance systems.

Estimated lifetime: 60,000 - 80,000 hours before comprehensive bottom-end overhaul (e.g., crankshaft out inspection/renewal)

Spares

Replacement Parts

Spare parts notes

Recommended: complete cylinder head spares, injectors, exhaust valves, bearing shells, piston rings and turbocharger kit.

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