M55
Weichai Marine M55 — Medium-speed main engine for large vessels, ocean-going ships.
Engine Specifications
Inspector Detail
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Common issues
- Turbocharger fouling on the compressor or turbine side, showing up as falling boost pressure and rising exhaust temperature
- Exhaust valve burning or seat recession on individual cylinders, seen as a growing exhaust temperature deviation between cylinders
- Injector wear (nozzle coking, needle sticking) causing rough running, white/black smoke or knock on the affected cylinder
- Cylinder liner wear and increasing blow-by from prolonged running at low load or on poor-quality fuel
- Cooling water leakage at liner O-rings or cylinder head gaskets, often first seen as coolant top-up creep
- Lube oil contamination or excessive consumption from worn piston rings or turbocharger oil seals
- Governor/speed control drift causing hunting or slow load response on the genset
Inspection checklist
- Record and trend exhaust gas temperature per cylinder; flag any cylinder deviating more than roughly 50 C from the mean
- Check turbocharger boost pressure and speed against the load diagram for signs of fouling or bearing wear
- Check crankcase pressure/oil mist level - do not ignore a rising trend, it precedes bearing failures
- Verify valve clearances against the maker's cold/hot settings at the scheduled interval
- Inspect injector spray pattern and opening pressure when pulled for service
- Check cylinder compression/firing pressure balance across cylinders where indicator/pressure pickup access exists
- Inspect cooling water for oil traces and lube oil for coolant/fuel dilution
- Check governor response, overspeed trip function and emergency stop operation
Service intervals
| Valve clearance check/adjustment | typically every 1,000-2,000 running hours |
| Injector service/exchange | typically every 2,000-4,000 h, engine and fuel quality dependent |
| Turbocharger cleaning/inspection | typically every 2,000-4,000 h, or per rising exhaust temperature trend |
| Lube oil and filter change | per the oil supplier's condemning limits and maker's base interval, typically every 250-500 h for a genset duty cycle |
| Top overhaul (piston/liner inspection) | typically every 8,000-16,000 h depending on load factor and fuel quality |
| Major overhaul (bearings, full strip) | typically every 16,000-24,000 h - confirm against this model's maker schedule |
Typical wear limits
| Piston ring end gap | typically 0.8-1.5 mm for this bore class - confirm against the engine's own manual |
| Cylinder liner bore wear/ovality | condemn per the maker's wear limit table, commonly in the region of 0.3-0.5% of bore diameter - confirm against this model's manual |
| Big-end/main bearing clearance | check against the maker's new and condemning clearance figures - varies by bearing size, no single figure applies |
| Valve clearance drift | re-set once measured clearance falls outside the maker's cold-setting tolerance band |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Fuel injectors (complete units, not just nozzles, for fast exchange)
- Piston ring set(s)
- Cylinder liner(s), one class of oversize where the maker offers repair sizes
- Main and big-end bearing shells
- Turbocharger cartridge/repair kit
- Cylinder head gasket set
- Exhaust and inlet valves with seats/guides
Safety
- Crankcase explosion risk from oil mist - never open crankcase doors immediately after a high-temperature bearing event; allow cooling and follow the maker's re-entry procedure
- Hot exhaust manifold and turbocharger casing surfaces during and shortly after running
- High-pressure fuel injection lines - treat any suspected pinhole leak as a skin-injection hazard, not a minor drip
- Rotating flywheel, coupling and cooling fan guards must be in place before running
- Stored energy in the starting air system (if air-started) - isolate and vent before working on the starting gear
Class survey
As a genset/auxiliary prime mover, class wants running-hour records, evidence of valve and injector service at the stated intervals, crankshaft deflection readings at overhaul, and a functioning overspeed trip verified by test. If enrolled in a Continuous Machinery Survey scheme, component-by-component overhaul records must be traceable against the survey cycle.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Verify SFOC compliance against IMO baseline for engine generation/year. WH28 (181 g/kWh) meets latest efficiency standards; WD12 (212 g/kWh) acceptable for auxiliary duty. Measure actual fuel consumption during sea trials.
Verify IMO EIAPP (Engine International Air Pollution Prevention) certificate. Check NOx (nitrogen oxide) and smoke number measurements. Confirm diesel particulate filter/SCR compliance status for engines built post-2016 for Tier III zones.
Inspect fuel polishing systems and separator effectiveness. Verify fuel storage tank cleanliness (ISO 4406 cleanliness code 16/14/11 minimum). Check injector spray patterns under load. For HFO-capable engines (CW200, CW250), confirm proper viscosity and pour point.
Measure outlet water temperature differential (target: 3-5 degrees C drop across cooler). Check intercooler fouling (common in 170, 6WH17, 8WH17). Inspect jacket water and lube oil temperatures under full load. Perform ultrasonic thickness test on cooler tubes for erosion corrosion.
Measure turbocharger boost pressure against load curve. Check lube oil pressure to turbo (minimum 1.5 bar). Perform borescope inspection for carbon buildup in compressor wheel. Monitor turbo case temperature with IR gun (typically <100 C at inlet manifold). Confirm oil drain line unrestricted.
Type-general inspection and maintenance points for this equipment category — not model-specific.
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