Yanmar 6EY26W

Common issues

• Fuel injector fouling and carbon build-up leading to poor atomization, increased exhaust temperatures, and cylinder liner wear.
• Exhaust valve seat wear and burning, often exacerbated by HFO operation and poor fuel injection, leading to compression loss and reduced power.
• Turbocharger compressor and turbine side fouling, reducing efficiency, increasing exhaust back pressure, and potentially causing surging.
• Charge air cooler contamination (air and water side), leading to reduced cooling efficiency, higher charge air temperatures, and increased thermal stress on components.
• Piston ring wear and groove carbonization, resulting in increased blow-by, lube oil consumption, and potential piston seizure.
• Main and connecting rod bearing wear, indicated by abnormal noise, increased lube oil temperature, or metal particles in oil analysis.
• High-pressure fuel pump element wear, leading to inconsistent fuel delivery and uneven cylinder loading.
• Lube oil contamination or degradation, affecting bearing life and overall engine health.

Inspection checklist

• **Operational Data Review:** Check engine logbook for running hours, load profile, fuel/lube oil consumption trends, exhaust gas temperatures (individual cylinders), turbocharger speed/boost pressure, and cooling water/lube oil pressures and temperatures. Look for deviations.
• **Visual Inspection for Leaks:** Inspect all fuel lines (especially high-pressure lines), lube oil lines, cooling water pipes, and exhaust gas connections for any signs of leakage. Pay close attention to fuel pump areas and injector sleeves.
• **Exhaust Gas Appearance & Sound:** Observe exhaust stack for abnormal smoke (black, white, blue). Listen for uneven firing, knocking, or unusual noises from the engine and turbocharger.
• **Turbocharger Inspection:** Check for abnormal noise, excessive vibration, and visually inspect compressor and turbine blades for fouling or damage (if access permits). Check axial and radial play if engine is stopped and cool.
• **Charge Air Cooler Condition:** Inspect the air side for oil mist and carbon deposits. Check the water side for signs of leakage or scaling. Monitor pressure drop across the cooler.
• **Crankcase Breather & Relief Valves:** Inspect breather for excessive blow-by. Check crankcase relief valves for signs of leakage or damage to flame traps.
• **Fuel System Integrity:** Inspect fuel filters, pre-heaters, and changeover valves for proper operation and absence of leaks. Verify fuel pressure and temperature are within limits.
• **Lube Oil System:** Check lube oil level, pressure, and temperature. Review recent lube oil analysis reports for wear metals, TBN, viscosity, and water content. Inspect filters.
• **Vibration and Mountings:** Check engine mountings for signs of deterioration or loose bolts. Observe engine for excessive vibration during operation.

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 Fuel Injector units or Nozzle Tips & Needles
• Exhaust Valve Spindles and Seat Rings
• Piston Ring Sets (at least one complete set per cylinder)
• Main and Connecting Rod Bearing Shells (one complete set)
• Full Gasket Set for Cylinder Head and Turbocharger
• Fuel and Lube Oil Filters (primary and secondary)
• High-Pressure Fuel Pump Elements (if individual per cylinder)
• Turbocharger Bearing Cartridge or Repair Kit

Safety

• **High-Pressure Fuel Leaks:** Risk of fire or serious injury from fine spray. Ensure all high-pressure fuel lines are double-walled or properly shielded.
• **Hot Surfaces:** Exhaust manifold, turbocharger, and other engine components operate at very high temperatures. Ensure insulation is intact and warning signs are present.
• **Rotating Machinery:** Guarding for flywheel, coupling, and other rotating parts must be in place and secure.
• **Pressurized Systems:** Starting air, cooling water, and lube oil systems are under pressure. Follow proper lockout/tagout procedures before opening.
• **Crankcase Explosions:** Ensure crankcase relief valves are in good condition and flame traps are clean. Monitor oil mist detector alarms if fitted.

Class survey

A class surveyor will typically focus on the engine's overall condition, maintenance records, and compliance with statutory requirements. Key checks include: verification of engine logbook entries (running hours, maintenance, alarms, fuel/lube oil consumption), operational tests of safety devices (overspeed trip, low lube oil pressure, high cooling water temperature, oil mist detector), inspection of crankcase relief valves and flame traps, integrity of high-pressure fuel lines and shielding, condition of exhaust gas piping and insulation, general cleanliness, absence of leaks, and security of mountings and foundations. For specific surveys (e.g., Special Survey), opening up of components like cylinder heads, pistons, or bearings may be required based on running hours or condition monitoring results.