6L6N18AL-DV

Common issues

• Turbocharger wear and failure due to contaminated lube oil or carbon deposits, leading to reduced efficiency and smoke under load.
• Fuel injector coking, wear, or nozzle blockage, resulting in poor atomization, high exhaust temperatures, and increased fuel consumption.
• Exhaust valve burning or seat wear, often caused by high thermal stress, poor combustion, or inadequate cooling.
• Cylinder liner scuffing or excessive wear, potentially due to insufficient lubrication, high thermal loads, or abrasive contaminants.
• Lube oil degradation or contamination (e.g., with fuel or water), leading to accelerated wear of bearings, piston rings, and other moving parts.
• Cooling water system blockages, scaling, or corrosion, causing localized overheating and reduced engine performance.
• Main and connecting rod bearing wear, typically linked to lube oil quality, contamination, or excessive engine loading.

Inspection checklist

• Exhaust gas analysis: Observe color (should be clear/light haze), measure individual cylinder exhaust gas temperatures (pyrometer readings) for balance.
• Turbocharger inspection: Check axial and radial play of the rotor shaft, inspect compressor and turbine sides for fouling, damage, or oil ingress.
• Fuel injection system: Visually inspect high-pressure fuel lines for leaks, check fuel injector nozzles for signs of dripping or poor atomization (if accessible during operation), and verify fuel pump rack positions.
• Lube oil system: Monitor lube oil pressure and temperature, check differential pressure across filters, verify oil level, and review recent lube oil analysis reports for contamination or degradation.
• Cooling water system: Check pressures, temperatures, expansion tank level, and visually inspect for leaks. Ensure heat exchangers are clean and free from blockages.
• Crankcase breather and oil mist detector: Inspect for excessive blow-by and verify the functionality of the oil mist detector (if fitted).
• Engine mountings and coupling: Visually inspect for integrity, signs of excessive vibration, or loose fasteners.
• Safety devices: Conduct functional checks of the overspeed trip, low lube oil pressure shutdown, and high cooling water temperature shutdown.

Service intervals

Typical wear limits

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

Critical spares

• Fuel Injector Nozzle / Complete Injector
• Fuel Filter Elements (Primary & Secondary)
• Lube Oil Filter Elements
• Exhaust Valve Spindle & Seat Ring
• Piston Ring Set (at least one complete set per cylinder)
• Turbocharger Bearing Cartridge / Repair Kit
• High-Pressure Fuel Pump Element
• Assorted Gaskets and O-rings (e.g., cylinder head, inspection covers)

Safety

• High-pressure fuel leaks: Risk of fire and explosion, especially with HFO, requiring immediate attention and proper shielding.
• Hot surfaces and exhaust system: Severe burn hazards from engine block, exhaust manifold, and turbocharger.
• Rotating machinery: Entanglement risk from flywheel, shafting, and turbocharger rotor during operation.
• Starting air system: High pressure (up to 30 bar) poses rupture and projectile hazards if components fail or are improperly handled.
• Crankcase oil mist: Potential for crankcase explosion if oil mist detector fails or is ignored, indicating internal component overheating.

Class survey

A class surveyor will typically check the following for a Yanmar 6L6N18AL-DV: 1. **Documentation Review**: Thorough examination of engine logbooks, maintenance records, oil analysis reports, and previous survey reports to verify adherence to Planned Maintenance System (PMS) and manufacturer guidelines. 2. **Operational Performance**: Verification of engine running parameters (pressures, temperatures, RPM, load) against manufacturer's specifications, ensuring stable operation and absence of abnormal conditions. 3. **Safety Devices**: Functional testing of critical safety devices including the overspeed trip, low lube oil pressure/high cooling water temperature alarms and shutdowns, and local/remote emergency stops. 4. **Visual Inspection**: Comprehensive check for leaks (fuel, lube oil, cooling water), abnormal vibrations, general cleanliness, securing of all engine components, and integrity of the exhaust gas system. 5. **Fuel Oil System**: Inspection of high-pressure fuel lines, leak-off arrangements, and fuel filter condition to prevent fire hazards and ensure proper fuel delivery. 6. **Starting Air System**: Verification of starting air bottle pressure, integrity of piping, relief valves, and non-return valves. 7. **Critical Spares**: Confirmation of availability and condition of essential spare parts onboard as per class requirements and vessel's trading area. 8. **Crankcase Inspection**: Depending on the running hours and survey type (e.g., Special Survey), an internal inspection of the crankcase for bearing condition, crankshaft deflection, and functionality of the oil mist detector.