What Is the Yanmar 6LT Marine Engine?
The Yanmar 6LT Marine Engine is a high-performance inline six-cylinder, four-stroke marine diesel engine family developed for fast boats, planing hulls, recreational vessels, and light-duty commercial marine applications.
The current Yanmar 6LT range consists of three principal models:
- Yanmar 6LT500 – 500 mhp / 367 kW
- Yanmar 6LT580 – 580 mhp / 426 kW
- Yanmar 6LT640 – 640 mhp / 470 kW
All three are rated at 2530 rpm. Yanmar positions the 6LT as its 500–640 mhp marine diesel range and lists it for both shaft-drive and jet-drive installations.
Alfa Marine Spare Parts supplies OEM, genuine, aftermarket, and remanufactured Yanmar 6LT marine engine spare parts for maintenance, repair, cooling-system service, fuel-system work, major component replacement, and engine overhaul requirements.
Yanmar 6LT Technical Information
Yanmar's published specifications provide the following core technical data for the 6LT family.
SpecificationYanmar 6LT SeriesManufacturerYanmarEngine Family6LTModels6LT500 / 6LT580 / 6LT640Engine Type4-stroke water-cooled dieselCylinder ArrangementInline 6Cylinders6Displacement8.710 LBore117 mmStroke135 mmCombustionDirect InjectionFuel SystemBosch Common RailMaximum Injection Pressure160 MPaAspirationTurbocharged with Air CoolerRated Speed2530 rpmCoolingLong-life coolant with heat exchangerLubricationForced lubricationControlsElectronicAlternator24 V / 90 AStarter24 V DC / 5.5 kWDry Weight Without GearApprox. 1,125 kgControl SystemYanmar VC20/VC30How Much Power Does the Yanmar 6LT Produce?
The 6LT family covers three power levels:
EngineRated PowerRated Speed6LT500367 kW / 500 mhp2530 rpm6LT580426 kW / 580 mhp2530 rpm6LT640470 kW / 640 mhp2530 rpm
This gives the 6LT family a relatively broad output range while retaining the same basic 8.71-liter inline-six engine architecture.
Is the Yanmar 6LT a Six-Cylinder Engine?
Yes.
The Yanmar 6LT is an inline six-cylinder diesel engine with:
- 6 cylinders
- 117 mm bore
- 135 mm stroke
- 8.710-liter displacement
Yanmar describes the configuration as an inline, vertical, four-stroke, water-cooled diesel engine.
Is the Yanmar 6LT a Four-Stroke Engine?
Yes.
The Yanmar 6LT operates on the four-stroke diesel cycle:
- Intake
- Compression
- Combustion and power
- Exhaust
The complete cycle takes place over two crankshaft revolutions.
What Fuel System Does the Yanmar 6LT Use?
The Yanmar 6LT uses Bosch common-rail direct fuel injection with electronic control.
According to Yanmar's operation manual, injection timing and pressure are variable, with maximum injection pressure listed at 160 MPa.
Available fuel-system components can include:
- Common-Rail Fuel Injectors
- High-Pressure Fuel Pumps
- Fuel Supply Pumps
- Fuel Rail Components
- Fuel Pressure Sensors
- Fuel Filters
- Fuel Filter Housings
- High-Pressure Fuel Pipes
- Fuel Supply Lines
- Injector Seals
- Injector O-Rings
- Fuel-System Gaskets
- Associated Electronic Components
Yanmar 6LT Fuel Injector Parts
The common-rail injectors deliver precisely controlled quantities of fuel into each cylinder.
Injector condition can affect:
- Starting
- Idle quality
- Engine power
- Acceleration
- Fuel consumption
- Cylinder balance
- Exhaust smoke
- Combustion quality
Available components can include:
- Complete Fuel Injectors
- Remanufactured Fuel Injectors
- Injector Seals
- Injector O-Rings
- Injector Hardware
- High-Pressure Fuel Pipes
- Associated Common-Rail Components
The exact injector should be matched to the complete engine model and serial number.
Yanmar 6LT High-Pressure Fuel Pump Parts
The high-pressure pump supplies the common rail with pressurized fuel for electronic injection.
Available components can include:
- Complete High-Pressure Fuel Pumps
- Fuel Supply Pumps
- Pump Seals
- Fuel Connections
- Pressure-Control Components
- Associated Gaskets
- Mounting Hardware
Because the fuel system operates at very high pressure, correct component identification is particularly important.
Is the Yanmar 6LT Turbocharged?
Yes.
Yanmar specifies the 6LT as turbocharged and intercooled/air-cooled.
Available turbocharger components can include:
- Complete Turbochargers
- Remanufactured Turbochargers
- Turbocharger Cartridges
- Compressor Components
- Turbine Components
- Bearings
- Seals
- Oil Supply Lines
- Oil Drain Lines
- Turbocharger Gaskets
- Mounting Hardware
Yanmar 6LT Charge-Air Cooler Parts
After the turbocharger compresses the intake air, the charge-air cooling system reduces its temperature before the air enters the engine.
Available components can include:
- Charge-Air Coolers
- Air Cooler Cores
- Cooler Housings
- End Covers
- Intake Pipes
- Hoses
- Clamps
- Gaskets
- O-Rings
- Seals
Yanmar 6LT Cylinder Head Parts
The cylinder head contains important components involved in combustion, airflow, exhaust flow, and fuel injection.
Available components can include:
- Complete Cylinder Heads
- Intake Valves
- Exhaust Valves
- Valve Guides
- Valve Seats
- Valve Springs
- Rocker Components
- Injector Components
- Cylinder Head Gaskets
- Cylinder Head Seals
- Associated Hardware
Yanmar 6LT Cylinder Liner Parts
Cylinder liners provide the running surfaces for the six pistons.
Available components can include:
- Cylinder Liners
- Liner Seals
- O-Rings
- Associated Sealing Components
Cylinder-liner condition can affect:
- Compression
- Blow-by
- Oil consumption
- Combustion sealing
- Cylinder performance
Yanmar 6LT Pistons and Piston Rings
Available piston-related components can include:
- Pistons
- Piston Rings
- Piston Pins
- Piston Pin Components
- Retaining Components
- Associated Hardware
Piston rings are important for combustion sealing, compression, oil control, and heat transfer between the piston and cylinder liner.
Yanmar 6LT Connecting Rod Parts
Connecting rods transfer combustion forces from the pistons to the crankshaft.
Available components can include:
- Connecting Rods
- Connecting Rod Bearings
- Connecting Rod Bushings
- Connecting Rod Bolts
- Associated Hardware
Yanmar 6LT Crankshaft and Bearing Parts
The crankshaft converts the reciprocating movement of the six pistons into rotational output.
Available components can include:
- Crankshafts
- Main Bearings
- Connecting Rod Bearings
- Thrust Bearings
- Front Crankshaft Seals
- Rear Crankshaft Seals
- Vibration Damper Components
- Associated Hardware
Yanmar 6LT Camshaft and Valve Train Parts
Available components can include:
- Camshafts
- Camshaft Bearings
- Timing Components
- Rocker Components
- Intake Valves
- Exhaust Valves
- Valve Guides
- Valve Seats
- Valve Springs
- Associated Hardware
Yanmar 6LT Marine Cooling System
The Yanmar 6LT uses a closed coolant system combined with a marine heat exchanger. Yanmar lists approximately 38 liters of coolant capacity for the engine.
Available cooling-system components can include:
- Freshwater Pumps
- Coolant Pumps
- Thermostats
- Thermostat Housings
- Heat Exchangers
- Coolant Pipes
- Coolant Hoses
- Temperature Sensors
- Cooling-System Gaskets
- O-Rings
- Seals
Yanmar 6LT Seawater Pump Parts
The raw-water circuit supplies seawater to the marine cooling system.
Available components can include:
- Complete Seawater Pumps
- Raw-Water Pumps
- Impellers
- Pump Shafts
- Pump Bearings
- Mechanical Seals
- Pump Covers
- Wear Components
- Gaskets
- O-Rings
- Raw-Water Connections
The exact seawater-pump configuration should be identified from the specific 6LT model and installation.
Yanmar 6LT Heat Exchanger Parts
Available heat-exchanger components can include:
- Complete Heat Exchangers
- Heat Exchanger Cores
- End Covers
- Gaskets
- O-Rings
- Seals
- Coolant Connections
- Raw-Water Connections
- Associated Hardware
Yanmar 6LT Lubrication System
Yanmar specifies a forced lubrication system for the 6LT. The operation manual lists total engine lubricating-oil capacity at approximately 28 liters, although service/fill quantities must always follow the applicable manual and installation.
Available lubrication components can include:
- Engine Oil Pumps
- Oil Filters
- Oil Filter Housings
- Oil Coolers
- Oil Cooler Components
- Oil Pressure Sensors
- Oil Lines
- Oil Pan Components
- Oil Seals
- Lubrication-System Gaskets
Yanmar 6LT Electronic Engine Components
Electronic control is an important part of the Yanmar 6LT platform.
The engines integrate with Yanmar's VC20/VC30 Vessel Control System, with CAN-bus controls and multifunction display capability.
Depending on configuration, components can include:
- Engine Control Components
- Fuel Pressure Sensors
- Oil Pressure Sensors
- Coolant Temperature Sensors
- Engine Speed Sensors
- Position Sensors
- Wiring Harnesses
- CAN-Bus Components
- Electronic Control Heads
- Monitoring Components
- Electrical Connections
Yanmar 6LT Starting and Charging Components
The 6LT uses a 24-volt electrical system. Yanmar specifies a 24 V, 5.5 kW starter motor and 24 V, 90 A alternator.
Available components can include:
- Starter Motors
- Alternators
- Starter Solenoids
- Relays
- Wiring Components
- Electrical Connections
- Associated Hardware
Yanmar 6LT Gaskets and Seals
Available sealing components can include:
- Cylinder Head Gaskets
- Valve Cover Gaskets
- Intake Gaskets
- Exhaust Gaskets
- Turbocharger Gaskets
- Charge-Air Cooler Gaskets
- Heat Exchanger Gaskets
- Water Pump Gaskets
- Oil-System Gaskets
- Injector Seals
- Cylinder Liner Seals
- Crankshaft Seals
- O-Rings
- Complete Gasket Sets
- Complete Engine Seal Kits
Yanmar 6LT Overhaul Parts
A major Yanmar 6LT marine engine overhaul can require components from several engine systems.
Available overhaul components can include:
- Cylinder Liners
- Pistons
- Piston Rings
- Piston Pins
- Main Bearings
- Connecting Rod Bearings
- Thrust Bearings
- Connecting Rod Components
- Cylinder Head Components
- Fuel Injectors
- Crankshaft Seals
- Complete Gasket Sets
- Complete Seal Kits
- Freshwater Pumps
- Seawater Pumps
- Oil Pumps
- Turbocharger Components
- Cooling-System Components
Depending on engine condition and availability, major replacement components can also include:
- Crankshafts
- Camshafts
- Connecting Rods
- Complete Cylinder Heads
- Turbochargers
- Charge-Air Coolers
- Heat Exchangers
- High-Pressure Fuel Pumps
- Common-Rail Components
Which Yanmar 6LT Models Do We Cover?
The Yanmar 6LT engine page covers the three primary engines currently listed in the family:
Yanmar 6LT500
367 kW / 500 mhp at 2530 rpm
Yanmar 6LT580
426 kW / 580 mhp at 2530 rpm
Yanmar 6LT640
470 kW / 640 mhp at 2530 rpm
All three share the 8.710-liter, six-cylinder architecture, although engine-specific components must still be matched to the exact model.
Where Is the Yanmar 6LT Marine Engine Used?
Yanmar describes the 6LT as suitable for fast boats, planing hulls, recreational craft, and light-duty commercial applications. It supports both shaft-drive and jet-drive configurations.
Applications can include:
- Fast Motor Yachts
- Recreational Powerboats
- Planing-Hull Vessels
- Light Commercial Craft
- Fast Workboats
- Patrol and Service Craft
- Passenger Craft
- Jet-Drive Applications
- Shaft-Drive Applications
HVO Compatibility
Yanmar currently identifies the 6LT500, 6LT580 and 6LT640 as HVO-approved engines.
How Are Yanmar 6LT Spare Parts Identified?
Correct identification is important because parts can differ between the 6LT500, 6LT580 and 6LT640, as well as according to production specification and marine installation.
Useful information includes:
- Engine model: 6LT500, 6LT580 or 6LT640
- Engine serial number
- Existing part number
- Component description
- Quantity required
- Engine rating
- Marine gear configuration
- Vessel control configuration
- Clear photographs of the existing component
- Delivery destination
For common-rail injectors, high-pressure fuel pumps, turbochargers, electronic components, seawater pumps, heat exchangers, and other configuration-dependent parts, complete engine identification is particularly important.