6LNTA855-M

Common issues

• Fuel injector nozzle wear or clogging, leading to poor combustion, increased smoke, and reduced power.
• Raw water pump impeller wear or failure, causing inadequate cooling and potential overheating.
• Turbocharger bearing wear or carbon buildup, resulting in excessive shaft play, reduced boost, and oil consumption.
• Cooling system heat exchanger fouling (saltwater side), leading to elevated engine temperatures.
• Lubricating oil leaks, particularly from rocker covers, oil pan gaskets, or front/rear crankshaft seals.
• Fuel system issues: Clogged fuel filters, fuel pump wear, or air ingress, causing power loss or difficult starting.
• Valve lash deviation, leading to improper valve timing, reduced efficiency, and increased wear on valvetrain components.
• Engine mount deterioration, causing excessive vibration and potential misalignment of coupled machinery.

Inspection checklist

• Check all fluid levels (lube oil, coolant) and their condition (color, contamination).
• Inspect for any visible leaks (fuel, oil, coolant, exhaust gas) around the engine and associated systems.
• Verify proper operation and readings of all engine gauges (oil pressure, coolant temperature, exhaust temperature, turbo boost).
• Examine fuel, lube oil, and air filters for signs of clogging or damage; note last replacement date.
• Listen for unusual noises (knocking, rattling, squealing) and observe engine vibration levels at various RPMs.
• Inspect the turbocharger for excessive shaft play (axial and radial) and signs of oil leakage or impeller damage.
• Check the condition and tension of all drive belts (alternator, raw water pump, etc.).
• Inspect the exhaust system for leaks, proper insulation, and the presence of excessive smoke (color and density).
• Verify the integrity of engine mounts for signs of cracking, compression, or detachment.
• Test emergency shutdown systems and safety alarms (low oil pressure, high water temperature, overspeed).

Service intervals

Typical wear limits

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

Critical spares

• Complete set of fuel filters (primary and secondary).
• Complete set of lube oil filters.
• Raw water pump impeller and gasket kit.
• Drive belts (alternator, raw water pump).
• Fuel injector (at least one spare, or a full set if budget allows).
• Thermostat and gasket.
• Assorted O-rings and common gaskets (e.g., rocker cover gasket).
• Engine oil and coolant (sufficient for top-ups).

Safety

• Hot surfaces: Exhaust manifold, turbocharger, and exhaust piping can cause severe burns. Ensure proper insulation and warning signs.
• Rotating machinery: Belts, pulleys, and flywheel pose entanglement hazards. Ensure guards are in place and secure.
• High-pressure fuel lines: Leaks can spray fuel, posing fire and skin penetration risks. Always depressurize before working on the fuel system.
• Pressurized cooling system: Opening the system when hot can release scalding coolant and steam. Allow to cool before servicing.
• Electrical hazards: Ensure proper lockout/tagout procedures are followed before working on electrical components, especially the starting system.

Class survey

A class surveyor will typically focus on the overall condition and operational safety of the engine. Key checks include: verification of engine logbook entries and maintenance records; visual inspection for leaks, corrosion, and cleanliness; testing of all safety devices (overspeed trip, low oil pressure/high temperature alarms and shutdowns); integrity of fuel lines and emergency shut-off arrangements; condition of exhaust system insulation and spark arrestor (if fitted); security and condition of engine mounts; functionality of starting systems (air or electric); and verification of remote control and instrumentation accuracy. Particular attention is paid to any modifications or repairs and their compliance with classification society rules, often requiring documentation of work performed and material traceability. Operational tests under load may be requested to confirm performance and absence of excessive smoke or vibration.