OceanSphereENGINES
Bergen Engines

C25:33L

Main Engine 4-Stroke · Main Engines (4-Stroke)

Technical data from manufacturer or class sources · not yet verified by a person​​‍​⁠⁠⁠‌​​​⁠⁠‌‍‌‍​⁠‌
6 / 9Cylinders
250 mmBore
330 mmStroke
MDO/HFOMedium

The Bergen C25:33L is a medium‑speed, four‑stroke diesel main engine (6–9 cylinders) used for ship propulsion and generator sets, featuring a 250 mm bore, 330 mm stroke, turbocharging with two‑stage charge‑air cooling and flexible rating from 720 to 1000 rpm.

Specifications

Technical data.reference — unverified

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Bmep25 bar @ 750 rpm (Propulsion), 26 bar @ 720 rpm (Genset)
SFOC (100% MCR)171-177 g/kWh (MDO basis, varies by cylinders)
SFOC (85% MCR)173-175 g/kWh
Lube Oil Consumption0.5 g/kWh
Mean Piston Speed11.2 m/s (@ 750 rpm), 10.8 m/s (@ 720 rpm)
Dry Weight L6P42,400 kg
Dry Weight L8P53,500 kg
Dry Weight L9P56,400 kg
Dry Weight V12P71,867 kg
Genset Weight L6A48,300 kg (engine only)
Genset Weight L8A60,600 kg (engine only)
Genset Weight L9A62,400 kg (engine only)
Engine Type4-stroke, turbocharged with 2-stage charge air cooler
Service IntervalsExtended up to 25,000 hours
IMO ComplianceTier II (standard), Tier III (with SCR)
Electrical Output L6 50Hz3,515 kW genset
Electrical Output L8 50Hz4,690 kW genset
Electrical Output L9 50Hz5,285 kW genset
Electrical Output V12 60Hz6,750 kW genset
Electrical Output V12 50Hz7,050 kW genset
Speed (rpm)720/750/900/1000
Service

Service notes.

What our service work and the manufacturer documentation say about keeping this model running.

Follow Bergen schedule for cylinder head, injector, turbocharger and bearing inspections.

Inspection

Inspector Detail ✓ verified

Common issues

  • Injector coking, especially with HFO operation or prolonged low-load running.
  • Exhaust valve wear and burning, often linked to fuel quality, high temperatures, or poor seating.
  • Turbocharger fouling (compressor and turbine sides), leading to reduced efficiency and surging.
  • Cooling water leakage from O-rings, pipe connections, or cylinder liner seals.
  • Piston ring wear or breakage, resulting in increased blow-by and lube oil consumption.
  • Main and connecting rod bearing wear due to lube oil contamination, degradation, or overload.
  • Fuel pump element wear, affecting injection timing and pressure.
  • Vibration and alignment issues, potentially leading to bearing damage or structural fatigue.

Inspection checklist

  • Visual inspection for leaks (fuel, lube oil, cooling water) around cylinder heads, fuel pumps, turbocharger, and pipe connections.
  • Monitor exhaust gas temperature deviation across cylinders (should be within +/- 20-30°C from average).
  • Review recent lube oil analysis reports for wear metals, TBN, viscosity, and water content.
  • Check turbocharger condition: inspect for axial/radial play, air filter cleanliness, and compressor/turbine blade fouling.
  • Inspect fuel injection system for external leaks, proper spray pattern (if possible via indicator valve), and fuel filter differential pressure.
  • Check cylinder head components: valve gear clearances, rocker arm condition, and pushrod integrity.
  • Assess engine vibration levels and verify tightness of engine mounting bolts.
  • Monitor cooling water system: pressure, temperature, expansion tank level, and signs of internal leakage (oil in water, water in oil).
  • Verify crankcase pressure and functionality of the oil mist detector.
  • Check governor/actuator response and condition of linkages.

Service intervals

Cylinder head top overhaul (valves, springs, seats)8,000 - 12,000 running hours
Fuel Injector overhaul/replacement3,000 - 6,000 running hours
Turbocharger inspection/cleaning8,000 - 12,000 running hours
Piston overhaul (rings, piston crown inspection)12,000 - 18,000 running hours
Main and connecting rod bearing inspection/renewal24,000 - 36,000 running hours
Major engine overhaul (crankshaft inspection, liner renewal)48,000 - 72,000 running hours

Typical wear limits

Cylinder liner wearMax 0.6 - 0.8 mm total ovality/taper from new diameter.
Crankshaft deflectionMax 0.05 - 0.10 mm (depending on engine length and manufacturer spec).
Main/Connecting rod bearing clearanceMax 0.15 - 0.25 mm over new clearance.
Exhaust valve seat recessionMax 0.5 - 1.0 mm from original position.
Piston ring groove wearMax 0.1 - 0.2 mm increase in axial clearance.
Turbocharger rotor axial playMax 0.15 - 0.25 mm (refer to specific TC manufacturer data).

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

Critical spares

  • Complete fuel injectors or nozzle tips (at least one set for one cylinder).
  • Exhaust valves and valve seats (or complete cylinder head if strategy allows).
  • Full set of piston rings for at least one cylinder.
  • Gasket and O-ring service kits for cylinder heads, fuel pumps, and common flanges.
  • Fuel pump elements (one set per engine or at least one spare).
  • Lube oil and fuel filters (primary and secondary).
  • Main and connecting rod bearing shells (at least one set).
  • Common sensors (temperature, pressure, speed).

Safety

  • High-pressure fuel lines: Risk of fuel spray causing fire or injury. Ensure proper screening and double-walled piping where applicable.
  • Hot surfaces: Exhaust manifold, turbocharger, and uninsulated pipes can cause severe burns. Verify insulation integrity.
  • Rotating machinery: Flywheel, coupling, and auxiliary drives pose entanglement risks. Ensure guards are in place and secure.
  • Crankcase explosion risk: Due to oil mist accumulation and hot spots. Ensure oil mist detector is functional and regularly tested.
  • Noise levels: Prolonged exposure requires hearing protection. Ensure engine room is properly marked for PPE.

Class survey

A class surveyor typically checks: Review of engine logbooks (running hours, maintenance records, alarm history, fuel consumption). Verification of safety devices (overspeed trip, low lube oil pressure shutdown, high cooling water temperature shutdown, oil mist detector alarm/shutdown). Fuel oil system integrity (leaks, proper screening of high-pressure lines, fire insulation, emergency shutdown). Exhaust gas system condition (insulation, expansion bellows, absence of leaks). Engine mountings and foundation bolts for tightness, corrosion, and signs of movement. Crankshaft deflection readings (required at specific intervals, e.g., 2.5 or 5-year surveys). Emergency stop functionality (local and remote). General cleanliness and housekeeping in the engine vicinity. Review of recent lube oil analysis reports and compliance with planned maintenance system.

Estimated lifetime: 80,000 - 120,000 hours before major overhaul (e.g., crankshaft regrinding, block line boring, full component renewal), assuming diligent maintenance.

Spares

Replacement Parts

Spare parts notes

Keep injector nozzles, exhaust valves, gasket kits, filters and bearing shells.

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