H25/33

Common issues

• Injector coking leading to poor combustion and high exhaust temperatures.
• Exhaust valve seat wear and burning, often due to poor fuel quality or rotator malfunction.
• Turbocharger fouling (compressor and turbine sides) reducing efficiency and increasing exhaust back pressure.
• Charge air cooler fouling (air and water sides) leading to high charge air temperatures and reduced engine performance.
• Piston ring sticking or scuffing, particularly with HFO operation, causing blow-by and increased lube oil consumption.
• Fuel pump element wear and leakage, affecting injection timing and pressure.

Inspection checklist

• Fuel Injectors: Check for leaks, proper securing, exhaust gas temperature deviation (indicating poor combustion), and fuel rack position consistency.
• Exhaust Valves: Verify rotator function, check valve clearances, and perform boroscope inspection for seat condition (burning, wear) if possible.
• Cylinder Liners & Pistons: Conduct borescope inspection for liner surface condition (scuffing, polishing), piston crown carbon build-up, and ring freedom. Measure liner wear at top ring reversal point.
• Turbocharger: Inspect compressor and turbine blades for fouling, erosion, or damage. Check axial and radial bearing play. Verify air filter condition.
• Charge Air Cooler: Monitor differential pressure across the air side. Visually inspect fins for fouling (air and water sides). Check drain system functionality.
• Crankcase: Check oil mist detector alarm and shutdown functionality. Inspect crankcase relief valves. Listen for unusual bearing noises.
• Fuel System: Check for high-pressure fuel line leaks, filter differential pressure, and condition of fuel pump elements.
• Lubricating Oil System: Verify correct lube oil pressure and temperature. Check filter differential pressure. Review recent lube oil analysis reports.

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 Injector Nozzles / Complete Injectors
• Exhaust Valve Spindles & Seats (or complete valve cages)
• Piston Rings (especially top compression rings)
• Cylinder Liner O-rings / Seals
• Turbocharger Bearing Cartridge / Seal Rings
• Fuel Pump Elements / Delivery Valves
• Main & Crankpin Bearing Shells (at least one set for emergency)
• Assorted Gaskets & O-rings (for cylinder head, inspection covers)

Safety

• High-pressure fuel line leaks: Risk of fire and severe injury from fuel spray. Ensure double-walled pipes and leak detection are functional.
• Hot surfaces: Exhaust manifold, turbocharger, and engine block pose severe burn hazards. Ensure insulation is intact.
• Crankcase explosion risk: Due to oil mist ignition. Verify functionality of oil mist detector and crankcase relief valves.
• Rotating machinery: Flywheel, shaft couplings, and turbocharger present entanglement risks. Ensure guards are in place.
• Working in confined spaces: Entry into crankcase or cylinder head requires strict permit-to-work procedures, gas testing, and standby personnel.

Class survey

For a HiMSEN H25/33 main engine, class surveyors typically focus on: 1. Crankshaft Deflection Readings: Mandatory for main engines, taken at multiple points for each throw. 2. Main & Crankpin Bearing Clearances: Spot checks on selected units if the engine is opened for maintenance. 3. Cylinder Liner Wear Measurements: Taken at the top ring reversal point and lower points, usually on 2-3 cylinders. 4. Exhaust Valve Condition: Visual inspection, and boroscope inspection for seat integrity and rotator function. 5. Fuel Injection System Integrity: Verification of high-pressure fuel line securing, leak-off system condition, and absence of leaks. 6. Safety Devices: Testing of overspeed trip, low lube oil pressure/high temperature shutdowns, oil mist detector alarm/shutdown, and emergency stops. 7. Engine Room Cleanliness & Fire Safety: General housekeeping, condition of insulation, and accessibility of fire fighting equipment. 8. Documentation Review: Engine logbook, maintenance records, running hours, lube oil analysis reports, fuel oil analysis reports, and previous survey reports.

Estimated lifetime: 100,000 - 150,000 running hours before major engine overhaul or replacement, assuming diligent maintenance and proper operation.