7S70ME-C8.5

Common issues

• Electronic Control System (ECS) malfunctions: Issues with hydraulic power supply (HPS) unit, control oil leaks, sensor failures (position, pressure, temperature), and actuator (fuel, exhaust valve) faults.
• Cylinder liner cold corrosion or scuffing: Often linked to low load operation, inadequate cylinder oil BN for fuel sulfur content, or poor fuel combustion.
• Exhaust valve burning and seat wear: Due to high thermal stress, poor fuel quality, or actuator issues leading to improper seating.
• Fuel injector fouling and wear: Caused by varying fuel quality (HFO/VLSFO/MGO), leading to poor atomization, increased fuel consumption, and higher thermal loads.
• Piston ring breakage or sticking: Resulting from poor combustion, excessive liner wear, or insufficient lubrication.
• Turbocharger bearing wear or fouling: Due to lubrication issues, high exhaust temperatures, or dirty intake air leading to reduced efficiency and potential damage.
• Scavenge space fires or port fouling: Accumulation of unburnt fuel and lube oil, particularly during prolonged low-load operation or slow steaming.
• Crosshead bearing wear: Though less common in modern designs, can occur due to lubrication failures, misalignment, or excessive loading.

Inspection checklist

• Cylinder Unit Condition: Inspect liner surface (via scavenge ports) for scuffing/wear, piston crown for deposits, piston rings for freedom, and exhaust valve spindle/seat for burning/deposits. Review indicator diagrams for combustion quality.
• Fuel Injection System: Check for external leaks from high-pressure pipes and fuel valves. Monitor fuel valve cooling oil flow/temperature. Verify actuator response and timing via ECS.
• Hydraulic Power Supply (HPS) Unit: Check hydraulic oil level, pressure, and temperature. Inspect for leaks from pumps, accumulators, and piping. Monitor filter differential pressure.
• Crankcase Inspection: Open crankcase doors to visually inspect main and crosshead bearings for signs of overheating or excessive clearance. Check connecting rod bolts. Verify oil mist detector functionality.
• Turbocharger: Check rotor free play (axial and radial). Inspect compressor and turbine blades for fouling, damage, or erosion. Verify bearing lubrication and cooling.
• Exhaust Gas System: Inspect exhaust valve actuators for leaks and smooth operation. Check exhaust manifold for leaks and insulation integrity.
• Engine Control System (ECS): Review alarm and event logs for recurring faults. Verify critical sensor readings against local gauges. Test emergency stop and safety shutdowns.
• Foundation Bolts and Chocking: Visually inspect all foundation bolts for tightness, corrosion, and signs of movement. Check chocking arrangements for degradation.
• Cooling Water & Lube Oil Systems: Check pressures, temperatures, and flow rates. Inspect filters and strainers. Review recent oil analysis reports (lube oil, cylinder oil, hydraulic oil).

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 Valve Unit (1-2 units)
• Exhaust Valve Spindle and Seat (1 set)
• Full set of Piston Rings for one cylinder
• Cylinder Liner O-rings and sealing rings
• High-Pressure Fuel Pipe (one set)
• Turbocharger Bearing Cartridge (1 unit)
• Main Bearing Shells (1 set for one position)
• Crosshead Bearing Shells (1 set for one position)
• Critical sensors for ME-C system (e.g., position sensors for fuel/exhaust valve actuators, speed sensor)
• Assortment of O-rings, gaskets, and seals for common components

Safety

• Crankcase Explosion Risk: Due to oil mist accumulation and potential hot spots. Ensure oil mist detector is functional and alarm settings are correct.
• High-Pressure Fuel and Hydraulic Oil Leaks: Both pose severe fire hazards and potential for injection injuries. All high-pressure lines must be shielded and regularly inspected.
• Hot Surfaces: Engine components, exhaust gas piping, and turbocharger casings are extremely hot. Risk of severe burns. Ensure proper insulation and warning signs.
• Rotating Machinery: Crankshaft, flywheel, turbocharger, and pumps pose entanglement risks. Ensure all guards are in place and secured during operation.
• Working in Confined Spaces: Scavenge space, crankcase, and exhaust ducts require proper ventilation, gas testing, and strict permit-to-work procedures before entry.
• Emergency Stop and Safety Devices: Critical to ensure these are fully functional and regularly tested to prevent catastrophic failures or accidents.

Class survey

Class surveyors typically check the overall engine condition (cleanliness, absence of leaks, corrosion, proper securing of components). They verify the functionality of all safety devices (overspeed trip, emergency stop, low lube oil pressure/high temp shutdowns, oil mist detector). A crankcase inspection (visual check of main/crosshead bearings, connecting rod bolts) and scavenge space inspection (deposits, fire flaps, drains) are common. Integrity of the fuel system (high-pressure pipe shielding, leaks) and exhaust gas system are checked. Review of engine control system alarm logs, critical sensor readings, and demonstration of control system functionality is expected. Maintenance records, running hours, oil analysis reports, and previous survey reports are scrutinized. Foundation bolts and chocking arrangements are inspected for tightness and signs of movement. Recent indicator diagrams are often reviewed for proper combustion and engine balance.