V35/44DF

Common issues

• Cylinder liner and piston ring wear, leading to increased lube oil consumption and blow-by, often exacerbated by varying load profiles or fuel quality.
• Exhaust valve burning or seat recession, particularly critical in Dual Fuel engines due to potentially higher exhaust gas temperatures or inconsistent combustion.
• Corrosion in cooling water passages (e.g., cylinder liners, charge air cooler) and external engine components due to seawater/salt air exposure.
• Malfunction or failure of electronic control units (ECUs), sensors, and actuators due to vibration, moisture ingress, or aging.
• Fuel system issues, including injector nozzle fouling/wear (diesel and pilot fuel) and gas valve unit (GVU) leakage or operational faults.
• Turbocharger bearing wear or fouling of compressor/turbine blades, leading to reduced engine performance and increased exhaust temperatures.
• Degradation of main and big-end bearings due to lubrication oil contamination, high loads, or extended service intervals.
• Issues with the gas train components, such as pressure regulators, safety valves, and gas block valves, leading to gas leaks or supply interruptions.

Inspection checklist

• Visual inspection for leaks (fuel, lube oil, cooling water, gas) around engine block, piping, and connections. Pay close attention to gas train components for signs of leakage or corrosion.
• Check exhaust gas temperatures (EGT) per cylinder for significant deviations (> +/- 30°C from average), indicating combustion imbalance or exhaust valve issues.
• Review engine logbook for lube oil analysis reports, crankshaft deflection readings, and operational parameters (e.g., start air pressure, cooling water temperatures, fuel consumption).
• Inspect turbocharger for signs of oil leakage, excessive axial/radial play, and cleanliness of compressor and turbine sides. Check air filter condition.
• Verify functionality of all safety devices: overspeed trip, low lube oil pressure shutdown, high cooling water temperature shutdown, and emergency stop buttons.
• Check condition of cylinder head components: valve rotators (if fitted), valve springs, rocker arm clearances, and fuel injector connections.
• Inspect external engine components for corrosion, loose fastenings, and integrity of insulation on hot surfaces (exhaust manifold, turbocharger).
• Monitor crankcase pressure and condition of the crankcase breather system for excessive blow-by or blockages.
• For DF operation, verify the integrity and functionality of the gas detection system in the engine room and around the gas supply train.

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

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

Critical spares

• Fuel Injectors (Diesel and Pilot Fuel) - complete units or nozzle tips
• Filter Elements (Fuel, Lube Oil, Air, Gas) - full sets
• Gasket Sets (Cylinder Head, Exhaust Manifold, Inspection Covers)
• Piston Rings (especially top compression ring and oil scraper ring)
• Main and Big End Bearing Shells (at least one complete set)
• Sensors (Temperature, Pressure, Speed, Gas Leakage) - common types
• O-rings and Seals (for critical systems like fuel, lube oil, cooling water, gas)
• Exhaust Valve Spindles and Seats (if known issue or high running hours)

Safety

• Gas leakage from the gas supply train or engine components (e.g., gas admission valves), posing a significant explosion risk in the engine room.
• High-pressure fuel lines (diesel and gas) - potential for spray fires if a line ruptures, especially in conjunction with hot surfaces.
• Hot surfaces (exhaust manifold, turbocharger, uninsulated piping) - risk of severe burns and potential ignition source for flammable liquids/gases.
• Crankcase explosion risk due to localized overheating (e.g., bearing failure, piston seizure) or accumulation of oil mist.
• Rotating machinery (flywheel, coupling, turbocharger) - entanglement and impact hazards during operation or maintenance.
• Malfunction of emergency shutdown systems (ESD) or overspeed protection, leading to uncontrolled engine operation or inability to stop in an emergency.

Class survey

The Class Surveyor will typically verify the engine's overall condition and compliance with classification rules. This includes reviewing maintenance records, logbooks, and lube oil analysis reports. They will witness operational tests of the main engine, including starting, stopping, and load changes. Critical safety devices such as overspeed trip, low lube oil pressure, and high cooling water temperature alarms/shutdowns will be tested. The integrity of the fuel oil and gas supply systems, including leakage detection and alarm functions, will be closely examined for Dual Fuel engines. Depending on the survey cycle (annual, intermediate, special), specific components like cylinder heads, bearings, or turbochargers may require opening for inspection. Crankshaft deflection readings from the logbook will be reviewed, and a live reading may be requested. Fire fighting and detection systems within the engine room are also a key focus.

Estimated lifetime: 60,000 - 80,000 running hours before major engine overhaul (e.g., crankshaft out, full rebuild), assuming diligent maintenance and operation within specified parameters.