6VPC2.5

Common issues

• Exhaust valve burning and corrosion, particularly with varying HFO quality and load changes.
• Fuel injection system problems: clogged nozzles, worn fuel pump plungers/barrels leading to poor combustion and high exhaust temperatures.
• Cylinder liner wear and scuffing, often exacerbated by poor lubrication or fuel quality.
• Turbocharger fouling (compressor and turbine sides) and bearing wear, leading to reduced boost pressure and engine performance.
• Main and connecting rod bearing wear, indicated by increased clearances or abnormal oil analysis results.
• Crankshaft deflection exceeding limits, pointing to foundation issues or bearing wear.
• Cooling water system blockages or leaks, affecting cylinder head and liner cooling efficiency.
• Vibration issues, potentially from misfiring cylinders, propeller imbalance, or engine mounting problems.

Inspection checklist

• Verify all engine parameters (RPM, load, exhaust gas temperatures per cylinder, cooling water temperatures/pressures, lube oil temperatures/pressures, fuel oil temperatures/pressures, boost pressure) are within specified limits.
• Inspect for any visible leaks (fuel, lube oil, cooling water, exhaust gas) around cylinder heads, fuel pumps, and pipe connections.
• Check crankcase relief valves for cleanliness and signs of oil mist or blow-by; inspect crankcase for abnormal noise or vibration.
• Observe exhaust smoke color and density (should be clear to light haze at normal load); listen for abnormal noises from turbocharger or engine internals.
• Verify proper operation of safety devices: overspeed trip, low lube oil pressure alarm/shutdown, high cooling water temperature alarm/shutdown, and crankcase oil mist detector.
• Inspect fuel oil filters and lube oil filters for differential pressure and signs of contamination.
• Check general cleanliness of the engine and surrounding area, ensuring no combustible materials are near hot surfaces.
• Examine turbocharger for excessive vibration, unusual noise, and signs of fouling on the compressor side.

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 assemblies or nozzles and needles.
• Exhaust valve spindles and seats (at least one set per cylinder).
• Piston rings (complete set for at least one cylinder).
• Main and connecting rod bearing shells (at least one set).
• Fuel pump plunger and barrel assembly, and delivery valves.
• Turbocharger bearing cartridge or complete rotor assembly.
• Various critical gaskets and O-rings (cylinder head, exhaust manifold, fuel system).
• Pressure relief valves for crankcase and fuel system.

Safety

• High surface temperatures: Exhaust manifold, turbocharger, and cylinder heads can cause severe burns. Ensure insulation is intact.
• High-pressure fuel lines: Potential for spray fires or injury from leaks, especially with HFO.
• Crankcase explosions: Risk from oil mist ignition due to hot spots or blow-by. Ensure oil mist detector and crankcase relief valves are functional.
• Rotating machinery: Danger from flywheel, crankshaft, and turbocharger rotor during engine operation or maintenance.
• Hot HFO: Handling hot, viscous HFO poses burn risks and requires proper PPE.
• Starting air system: High-pressure air can cause severe injury if not handled correctly during maintenance.

Class survey

A class surveyor will typically focus on the overall condition and operational integrity of the engine. This includes reviewing engine logbooks, maintenance records, lube oil analysis reports, and spare parts inventory. Key checks involve verifying the functionality of safety devices (overspeed trip, low LO pressure, high CW temp, crankcase oil mist detector, relief valves), assessing crankshaft deflection, and inspecting accessible components for wear, leaks, and corrosion. During Special Surveys (every 5 years), more intrusive inspections are required, often involving opening up a representative number of cylinder units (piston, liner, cylinder head), main and connecting rod bearings, and a thorough inspection of the turbocharger and fuel injection system. The surveyor will also check the engine's foundation, mounting, and alignment, as well as the condition of associated systems like starting air, fuel oil, lube oil, and cooling water.