What Is the Yanmar 6AY Marine Engine?
The Yanmar 6AY Marine Engine is a heavy-duty inline six-cylinder marine diesel engine family developed for commercial propulsion applications.
Yanmar's 6AY family includes several configurations and ratings, including models such as the 6AYM-WST, 6AYM-WET, 6AYM-WGT and 6AYAM-ET. The 6AY platform uses direct injection, turbocharging and intercooling, with specifications varying by model.
The 6AY series is particularly suited to commercial marine applications requiring substantial low- and mid-speed propulsion power, including fishing vessels, workboats and other heavily utilized craft.
Alfa Marine Spare Parts supplies OEM, genuine, aftermarket, and remanufactured Yanmar 6AY marine engine spare parts for scheduled maintenance, repairs, rebuilding and overhaul requirements.
Yanmar 6AY Technical Information
Yanmar's published specifications for the 6AY series include the following principal data.
SpecificationYanmar 6AY SeriesManufacturerYanmarEngine Family6AYEngine TypeMarine dieselCylinders6Cylinder ArrangementInlineBore155 mmStroke180 mmDisplacement20.379 LCombustionDirect injectionAspirationTurbocharger + intercoolerStarting System24V electric starterCoolingHeat exchanger on 6AYM versions; configuration variesEmissionsIMO Tier II on listed 6AYM versionsApplicationCommercial marine propulsion
The exact specifications should always be matched to the complete engine designation because power rating, cooling arrangement, marine gear and other equipment vary between 6AY models.
Which Yanmar 6AY Marine Engine Models Are Available?
Yanmar publishes several models within the commercial 6AY family, including:
- Yanmar 6AYAM-ET
- Yanmar 6AYM-WST
- Yanmar 6AYM-WET
- Yanmar 6AYM-WGT
Yanmar also lists additional AY-family configurations in certain markets, including the 6AYP-WGT and other variants.
How Much Power Does the Yanmar 6AY Produce?
Power depends significantly on the exact engine model and duty rating.
Published Yanmar specifications include:
ModelRatingRated Output6AYAM-ETC555 kW / 755 mhp @ 1840 rpm6AYM-WSTC485 kW / 659 mhp @ 1900 rpm6AYM-WETC555 kW / 755 mhp @ 1840 rpm6AYM-WETM610 kW / 829 mhp @ 1900 rpm6AYM-WGTL670 kW / 911 mhp @ 1938 rpm
This wide range is one reason the complete model and rating are important when identifying Yanmar 6AY spare parts.
Is the Yanmar 6AY a Six-Cylinder Engine?
Yes.
The Yanmar 6AY uses an inline six-cylinder configuration.
For the 6AYM models, Yanmar specifies:
- 6 cylinders
- 155 mm bore
- 180 mm stroke
- 20.379-liter displacement
The inline-six arrangement is well suited to commercial marine propulsion where high torque and durable continuous-duty operation are important.
What Fuel System Does the Yanmar 6AY Use?
The 6AY family uses direct fuel injection, but the exact fuel-system architecture depends on the model.
For example, Yanmar describes the 6AYM-WST as a mechanical engine, so the 6AY family should not be described generally as a modern common-rail engine.
Available fuel-system components can include:
- Fuel Injectors
- Injection Pumps
- Fuel Supply Pumps
- Fuel Filters
- Fuel Strainers
- Fuel Lines
- Injector Components
- Fuel-System Seals
- O-Rings
- Fuel-System Gaskets
- Associated Hardware
Correct fuel-system parts should be matched to the exact engine model and serial number.
Yanmar 6AY Fuel Injector Parts
The fuel injectors deliver fuel into each cylinder for combustion.
Injector condition can influence:
- Starting
- Engine power
- Fuel consumption
- Exhaust smoke
- Cylinder balance
- Combustion quality
- Engine response
Available components can include:
- Complete Fuel Injectors
- Injector Nozzles
- Injector Components
- Injector Seals
- Injector Hardware
- Fuel Pipes
- Associated Fuel-System Parts
Is the Yanmar 6AY Turbocharged?
Yes. Yanmar lists the 6AY series with turbocharger and intercooler aspiration.
The turbocharger uses exhaust-gas energy to increase the mass of air entering the cylinders.
Available turbocharger components can include:
- Complete Turbochargers
- Turbocharger Cartridges
- Compressor Components
- Turbine Components
- Bearings
- Seals
- Oil Supply Components
- Oil Drain Components
- Turbocharger Gaskets
- Mounting Hardware
What Does the Yanmar 6AY Intercooler Do?
Compressing intake air with a turbocharger increases its temperature.
The intercooler removes part of this heat before the air enters the cylinders.
Available components can include:
- Intercoolers
- Air Cooler Cores
- Intake Pipes
- Air Connections
- Hoses
- Clamps
- Gaskets
- O-Rings
- Seals
Does the Yanmar 6AY Use Four Valves per Cylinder?
Yanmar's documentation for the 6AYM-WET describes a four-valve-per-cylinder design intended to support combustion efficiency.
Available valve-train components can include:
- Intake Valves
- Exhaust Valves
- Valve Guides
- Valve Seats
- Valve Springs
- Rocker Components
- Camshaft Components
- Associated Hardware
Yanmar 6AY Cylinder Head Parts
The cylinder head contains important combustion, fuel-injection, intake and exhaust components.
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 6AY Cylinder Liners
The cylinder liners provide the working surfaces for the six pistons.
Available components can include:
- Cylinder Liners
- Liner Seals
- O-Rings
- Associated Sealing Components
Liner condition can influence:
- Compression
- Blow-by
- Oil consumption
- Combustion sealing
- Engine performance
Yanmar 6AY Pistons and Piston Rings
Available piston components can include:
- Pistons
- Piston Rings
- Piston Pins
- Retaining Components
- Associated Hardware
The piston rings perform several important functions:
- Sealing combustion pressure
- Maintaining compression
- Controlling lubricating oil
- Transferring heat from the piston to the liner
Yanmar 6AY Connecting Rod Components
Connecting rods transfer combustion force from the six pistons to the crankshaft.
Available components can include:
- Connecting Rods
- Connecting Rod Bearings
- Connecting Rod Bushings
- Connecting Rod Bolts
- Associated Hardware
Yanmar 6AY Crankshaft and Bearing Components
The crankshaft converts reciprocating piston movement into rotational output for the vessel's propulsion system.
Available components can include:
- Crankshafts
- Main Bearings
- Connecting Rod Bearings
- Thrust Bearings
- Front Crankshaft Seals
- Rear Crankshaft Seals
- Vibration Damper Components
- Associated Hardware
Yanmar 6AY 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 6AY Marine Cooling System
Heat-exchanger cooling is used on the 6AYM-WST, 6AYM-WET and 6AYM-WGT configurations listed by Yanmar. The 6AYAM-ET uses keel cooling with an optional heat exchanger.
Available cooling components can include:
- Freshwater Pumps
- Thermostats
- Thermostat Housings
- Heat Exchangers
- Coolant Pipes
- Coolant Hoses
- Temperature Components
- Cooling-System Seals
- O-Rings
- Gaskets
Yanmar 6AY Seawater Pump Parts
For heat-exchanger-cooled marine installations, the raw-water circuit provides seawater flow through the cooling equipment.
Available components can include:
- Complete Seawater Pumps
- Raw-Water Pumps
- Impellers
- Pump Shafts
- Pump Bearings
- Mechanical Seals
- Pump Covers
- Gaskets
- O-Rings
- Raw-Water Connections
The exact arrangement depends on the engine and marine installation.
Yanmar 6AY Heat Exchanger Parts
Available components can include:
- Complete Heat Exchangers
- Heat Exchanger Cores
- End Covers
- Gaskets
- O-Rings
- Seals
- Freshwater Connections
- Raw-Water Connections
Yanmar 6AY Lubrication System Parts
Available lubrication components can include:
- Engine Oil Pumps
- Lubricating-Oil Filters
- Filter Housings
- Oil Coolers
- Oil Cooler Components
- Oil Pressure Components
- Oil Lines
- Oil Pan Components
- Oil Seals
- Lubrication-System Gaskets
Yanmar also lists lubricating-oil cartridges among genuine maintenance components for the 6AY family.
Yanmar 6AY Gaskets and Seals
Available sealing components can include:
- Cylinder Head Gaskets
- Valve Cover Gaskets
- Intake Gaskets
- Exhaust Gaskets
- Turbocharger Gaskets
- Air Cooler Gaskets
- Freshwater Cooler Gaskets
- Water Pump Gaskets
- Oil-System Gaskets
- Injector Seals
- Cylinder Liner Seals
- Crankshaft Seals
- O-Rings
- Complete Gasket Sets
- Engine Seal Kits
Yanmar 6AY Overhaul Parts
A major Yanmar 6AY 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
- Cylinder Head Components
- Fuel Injectors
- Crankshaft Seals
- Complete Gasket Sets
- Complete Seal Kits
- Freshwater Pumps
- Oil Pumps
- Turbocharger Components
- Cooling-System Components
Depending on engine condition and parts availability, major replacement components can also include:
- Crankshafts
- Camshafts
- Connecting Rods
- Cylinder Heads
- Turbochargers
- Heat Exchanger Components
- Fuel-System Components
What Marine Applications Use the Yanmar 6AY?
The 6AY is a commercial marine propulsion engine. Real-world Yanmar examples include the 6AYM-WET operating as a main engine in pusher tugs and commercial aquaculture support vessels.
Applications can include:
- Fishing Vessels
- Workboats
- Pusher Tugs
- Commercial Support Vessels
- Aquaculture Vessels
- Service Craft
- Commercial Propulsion Applications
- Other Heavy-Duty Marine Installations
How Are Yanmar 6AY Spare Parts Identified?
Correct identification is important because the 6AY family contains different engine models, ratings and cooling arrangements.
Useful information includes:
- Engine family: Yanmar 6AY
- Complete engine model
- Engine serial number
- Existing part number
- Part description
- Quantity required
- Engine rating
- Rated speed
- Marine configuration
- Existing component photographs
- Delivery destination
For fuel-injection equipment, turbochargers, seawater pumps, heat exchangers and other configuration-dependent components, the complete engine designation and serial number help distinguish the correct replacement part.