Main Engine 4-Stroke · Main Engines (4-Stroke)
The MaK M 20 C is a medium‑speed (900–1000 rpm) four‑stroke diesel main engine offering up to ~3 MW of power with flexible fuel capability (MDO, HFO). Its defining feature is the high‑performance KBB turbocharger and redesigned charge‑air cooler that deliver low specific fuel consumption.
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What our service work and the manufacturer documentation say about keeping this model running.
Typical MaK service includes scheduled valve, injector, turbocharger and bearing inspections.
| Cylinder head overhaul (valves, springs, seats) | 8,000 - 12,000 hours |
|---|---|
| Fuel injector overhaul/renewal | 3,000 - 6,000 hours |
| Turbocharger minor overhaul (cleaning, bearing check) | 6,000 - 8,000 hours |
| Turbocharger major overhaul (rotor balancing, full bearing replacement) | 12,000 - 24,000 hours |
| Piston overhaul (rings, connecting rod bearings) | 16,000 - 24,000 hours |
| Main bearing inspection/renewal | 24,000 - 32,000 hours |
| Fuel injection pump overhaul | 12,000 - 16,000 hours |
| Charge air cooler cleaning | 4,000 - 8,000 hours (depending on operating conditions) |
| Cylinder liner wear (max diameter increase) | 0.6 - 0.8 mm (measured at top ring reversal point) |
|---|---|
| Crankshaft deflection (max deviation between adjacent webs) | 0.05 - 0.10 mm (depending on manufacturer's specific limits and engine size) |
| Exhaust valve seat recession | 0.5 - 1.0 mm (from original position, check manufacturer's specific limit) |
| Connecting rod bearing clearance (max increase) | 0.10 - 0.15 mm (from new clearance) |
| Main bearing clearance (max increase) | 0.15 - 0.20 mm (from new clearance) |
| Piston ring groove wear (axial clearance increase) | 0.15 - 0.25 mm (depending on ring position and manufacturer's limit) |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
During annual surveys, the surveyor will typically check engine logbooks, maintenance records, oil analysis reports, and verify the functionality of safety devices (overspeed trip, low lube oil pressure shutdown, high jacket water temperature shutdown, OMD alarm). For intermediate and special surveys, more in-depth inspections are required. This includes opening crankcase inspection doors to check main and connecting rod bearings (visual inspection, sometimes clearance checks), removing cylinder heads for valve and piston crown inspection, and potentially withdrawing pistons for ring and liner inspection. The surveyor will also pay close attention to the integrity of the engine's foundation, pipework (fuel, lube oil, cooling water, exhaust), and fire prevention measures (e.g., high-pressure fuel line shielding, insulation). Performance tests, including load trials and exhaust temperature monitoring, are often conducted to confirm engine health and compliance with regulatory requirements.
Estimated lifetime: 80,000 - 120,000 hours (before major overhaul like crankshaft regrinding or engine block line boring, assuming diligent maintenance and operation)
Keep injector nozzles, exhaust valves, piston rings, bearing shells, filters and gasket kits.
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