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Wärtsilä

7RT-flex96C

Name: Wärtsilä 7RT-flex96C
Brand: Wärtsilä
SKU: OSE-38904

The Wärtsilä 7RT‑flex96C is a low‑speed, two‑stroke marine diesel engine delivering up to 40 040 kW at 102 rpm, distinguished by its common‑rail fuel injection and camshaft‑less design for high torque and flexible fuel use.

40040.0 kW

Power

Engine Specifications

Cylinders

960 mm

Bore

2500 mm

Stroke

40,040 kW

MCR Power

102.0 rpm

MCR RPM

2-stroke

Stroke Type

Family: Wartsila RT-flex · Tier: IMO Tier II · Fuel: HFO, VLSFO, MDO

Inspector Detail

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Common issues

Fuel injection control system (RT-flex common-rail control) faults causing cylinder-to-cylinder combustion imbalance
Exhaust valve and seat wear/burning, aggravated by poor quality HFO
Cylinder liner wear and scuffing, aggravated by incorrect cylinder lubrication feed rate
Piston ring and ring groove wear with increasing blow-by over time
Common-rail/servo oil hydraulic system leakage or pump wear affecting injection and exhaust valve actuation
Turbocharger fouling (turbine and compressor side) reducing scavenge air pressure and raising exhaust temperature
Crosshead and main bearing wear from lubricating oil contamination or degraded oil condition
Fuel injector nozzle wear/coking causing poor spray pattern and increased exhaust smoke

Inspection checklist

Check exhaust gas temperature spread between cylinders - deviations beyond manufacturer's tolerance indicate injection or valve problems
Inspect scavenge ports/space for deposits, water or oil accumulation via drain checks
Check cylinder liner wear by bore gauge measurement at scheduled intervals
Inspect piston rings and ring grooves at piston overhaul
Check exhaust valve rotation, spindle condition and seat burning at overhaul
Monitor lubricating oil analysis (wear metals, TBN, water content) for crosshead/main bearings
Inspect turbocharger bearings, nozzle ring and blades for fouling/erosion
Check common-rail/servo oil system pressure and hydraulic pump condition
Verify cylinder lubrication feed rate and distribution against load and fuel sulphur content
Take crankshaft deflection readings at scheduled intervals
Check fuel injector spray pattern/condition at scheduled removal

Service intervals

Cylinder lubrication feed rate	continuously adjusted per running condition and fuel sulphur, per Wartsila feed-rate guidance
Lube oil analysis	every 500-1000 hours for system oil, plus ongoing cylinder oil monitoring
Piston overhaul (inspection/ring renewal)	typically every 12,000-24,000 hours, condition-based - confirm against Wartsila maintenance schedule
Exhaust valve overhaul	typically every 8,000-16,000 hours, condition-based
Turbocharger overhaul	typically every 12,000-24,000 hours per manufacturer's interval
Fuel injector inspection/service	every 4,000-8,000 hours or per condition
Crankshaft deflection check	every 2,000-4,000 hours or per class requirement

Typical wear limits

Cylinder liner wear	bauart-typical renewal around 0.6-1.0% of bore diameter for this engine class - confirm the exact limit against the Wartsila 7RT-flex96C instruction manual
Piston ring gap	varies by ring position and running hours - confirm against the Wartsila manual rather than assuming a generic figure
Exhaust valve seat recession/burning	condition-based rejection per Wartsila inspection criteria, not a fixed millimetre figure
Crankshaft deflection	acceptable range is engine- and class-specific - always use the class-approved deflection limit for this engine, not a generic value

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

Critical spares

Fuel injection valves/nozzles (cylinder set)
Exhaust valve spindles and seats
Piston rings (full set per cylinder)
Cylinder liners (long lead time - track wear trend)
Main/crosshead/big-end bearing shells
Turbocharger nozzle ring and bearing set
Servo oil/common-rail system seals and hydraulic components
Cylinder lubricator injectors

Safety

Crankcase explosion risk from oil mist accumulation - oil mist detectors must be functional and never bypassed
High-pressure common-rail/servo oil system - fully depressurise before opening any hydraulic connection
Scavenge air fire risk from oil/deposit accumulation - keep scavenge spaces clean and drains clear
Hot exhaust and turbocharger surfaces
Heavy rotating/reciprocating components - proper lifting gear and lockout required for piston/liner work
HFO handling and heating systems present a hot-fuel burn hazard

Class survey

Main propulsion engines of this size are typically enrolled in a Continuous Machinery Survey (or equivalent) scheme - class reviews crankshaft deflection records, cylinder/piston overhaul history, turbocharger overhaul records and crankcase oil mist detection function; camshaft-less common-rail engines like the RT-flex also require records of hydraulic/servo system maintenance and control system diagnostics.

Estimated lifetime: Major structural components (bedplate, frame, crankshaft) are typically designed for 20+ years/100,000+ running hours with scheduled overhauls; wearing parts (liners, rings, injectors, turbocharger components) are renewed on the shorter condition-based cycles noted above - confirm against Wartsila's maintenance planner for this engine