Yanmar 6EY26W Specifications
| Engine Model: Yanmar 6EY26W |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 7,481 cu.in (122.6 L) |
| Rated Engine Power: 1972-2574 Hp (1471-1920 kW) at 750 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 6EY26W is a medium-speed, 4-stroke,
vertical, water-cooled inline-6 diesel engine designed for marine
propulsion in commercial vessels such as workboats, fishing boats, and
crab fishing vessels. As part of Yanmar’s EY26 series, this engine is
engineered for the demanding requirements of continuous commercial
operation. The 6EY26W features direct injection, turbocharging, and an
intercooler to optimize combustion efficiency and power output.
The engine is widely recognized for its compact dimensions relative to
its displacement, high reliability, and operational economy. It complies
with IMO Tier II emission regulations, with some variants supporting IMO
Tier III compliance through selective catalytic reduction (SCR)
after-treatment systems. The engine is commonly paired with Yanmar
YXH-2000 or YXH-2500 series marine gears and is designed for continuous
heavy-duty operation at a rated speed of 750 rpm.
The Yanmar 6EY26W exemplifies modern medium-speed marine diesel
engineering, balancing robust power delivery with a focus on fuel
efficiency and low emissions. The engine displaces 122.6 liters,
achieved through a large bore and stroke of 260 mm by 385 mm. This
long-stroke configuration generates high torque at low engine speeds, a
critical advantage for maneuvering heavy displacement vessels and
maintaining propeller efficiency. The direct injection combustion
system, combined with turbocharging and an intercooler, ensures complete
fuel combustion, resulting in a low specific fuel consumption of
approximately 194 g/kW·h at 100% load.
The engine is offered in continuous power ratings from 1471 kW (1972 hp)
to 1920 kW (2574 hp), all at 750 rpm. The mean effective pressure ranges
from 1.92 to 2.50 MPa, while the mean piston speed is 9.63 m/s. The
valvetrain uses an overhead valve (OHV) arrangement with pushrods,
actuated by a camshaft located in the cylinder block. The forced
lubrication system employs a gear-type pump, and the cooling system uses
forced circulation fresh water cooling with an engine-driven pump.
Starting is accomplished via a turbine-type air motor. The engine’s dry
weight is approximately 18,500 kg (40,785 lb), with total weight
reaching 22,549 to 23,840 kg (49,700-52,560 lb) when paired with a
marine gear. With proper maintenance, the 6EY26W delivers a long service
life in harsh marine environments, including dedicated continuous
operation in displacement hull vessels.
Engine Type: 4-stroke, vertical, water-cooled inline-6 diesel
Valvetrain: Overhead valve (OHV), 12 valves (2 per cylinder)
Aspiration: Turbocharged with intercooler (air cooler)
Displacement: 122.6 L (7,481 cu.in)
Bore: 260.0 mm (10.24 in)
Stroke: 385.0 mm (15.16 in)
Combustion System: Direct injection
Firing Order: 1-3-5-6-4-2 (6-cylinder sequence)
Rotation (viewed from flywheel side): Counter-clockwise
Rated Engine Speed: 750 rpm
Mean Piston Speed: 9.63 m/s (31.6 ft/s)
Mean Effective Pressure: 1.92 - 2.50 MPa (278 - 363 psi)
Power Ratings (Continuous):
1471 kW (2000 PS / 1972 hp) @ 750 rpm
1620 kW (2203 PS / 2172 hp) @ 750 rpm
1920 kW (2610 PS / 2574 hp) @ 750 rpm
The cylinder block is a monobloc casting manufactured from high-strength
alloy cast iron with additional alloying elements for corrosion
resistance in seawater environments. The block incorporates replaceable
wet-type cylinder liners for longevity and serviceability, allowing
in-frame overhaul without engine removal. The liners are centrifugally
cast from hardened iron and sealed at the bottom with rubber O-rings to
prevent coolant migration into the crankcase.
The block uses an open-deck configuration with integral water jackets
surrounding each liner. Seven main bearing bulkheads are cast integrally
with the block, supporting a forged steel crankshaft with
induction-hardened journal surfaces.
The crankcase is of a deep-skirted design, extending well below the
crankshaft centerline to form a rigid ladder frame that minimizes
torsional vibration under heavy load. The timing gear housing at the
front of the block contains the gear train that drives the camshaft,
injection pump, fresh water pump, and any auxiliary drives such as the
air compressor. Cast-in passages form the main oil gallery, running the
full length of the block on the right side.
The cylinder head is a single, cross-flow casting manufactured from cast
iron. The combustion chambers are of the direct-injection open type,
machined into the piston crown as a re-entrant bowl shape that promotes
air-fuel mixing. The cylinder head carries two valves per cylinder: one
intake and one exhaust, arranged in a straight line along the head
centerline. This two-valve layout provides sufficient flow area for the
medium-speed operating range while maintaining simplicity and
robustness.
Valves are constructed from heat-resistant silichrome steel, with
exhaust valves featuring stellite-faced tips and hardened seats for
durability under high exhaust gas temperatures generated by
turbocharging. Valve seats are replaceable pressed-in inserts. The
valvetrain operates via a camshaft located in the cylinder block.
Mechanical lifters (solid tappets) follow the camshaft lobes and
transfer motion through hardened pushrods to forged steel rocker arms.
The rocker arms pivot on a through-shaft mounted above the cylinder
head. Valve lash adjustment uses a screw-and-locknut arrangement at the
rocker arm-to-valve stem interface. Adjustments are performed with the
engine cold. The cylinder head gasket is a multi-layer steel (MLS)
design with elastomer sealing beads and fire rings around each cylinder
to withstand the high cylinder pressures of turbocharged operation.
The fuel system is a mechanical direct-injection design. An in-line
injection pump, of Bosch or Yanmar-manufactured type, is mounted on the
cylinder block and driven by the timing gear train. The pump contains
six individual pumping plungers, one per cylinder, arranged in a
straight line. Each plunger is actuated by a camshaft within the pump
housing. A mechanical centrifugal governor maintains engine speed under
varying loads by adjusting fuel delivery.
A manual fuel shut-off lever stops the engine by cutting fuel supply. A
gear-type feed pump, mounted on the injection pump body, draws fuel from
the day tank and delivers it through a water-separating fuel filter and
a fine secondary filter to the injection pump. Each cylinder has a
multi-hole injector nozzle (hole-type) mounted vertically in the
cylinder head, with the nozzle tip extending into the piston bowl.
Injectors are spring-loaded, calibrated to open at a precise pressure.
Excess fuel not injected returns to the fuel tank through a return line
for pump cooling and aeration prevention. The injection pump timing is
set using a dial indicator and shims. The system is designed for
operation on marine diesel oil (MDO) of ISO 8217 grade, with a maximum
viscosity suitable for the injection pump.
The lubrication system is a forced, full-flow wet-sump design. A
gear-type oil pump is mounted internally on the front of the crankshaft
within the timing gear case. The pump draws oil through a screened
pickup tube from a fabricated steel oil sump. The total system oil
capacity is dependent on the specific sump configuration and is
specified in the engine operation manual. Oil passes through the pump
and then through a full-flow, spin-on or cartridge-type oil filter
mounted on the cylinder block.
An integral bypass valve within the filter housing allows unfiltered oil
to circulate if the filter becomes restricted. From the filter,
pressurized oil enters the main oil gallery, a longitudinal passage
drilled through the cylinder block. The main gallery distributes oil to
all seven main bearings through cross-drilled passages. Connecting rod
bearings receive oil from the main bearings via diagonal passages
drilled through the crankshaft. A separate vertical passage in the
cylinder block carries oil to the cylinder head, where it reaches the
rocker shaft and rocker arms through external lines.
Oil pressure is regulated by a spring-loaded relief valve located on the
oil pump housing. A water-cooled oil cooler, using fresh water from the
engine cooling circuit, maintains oil temperature within an optimal
range. A turbocharger oil feed line, supplied from the main gallery,
routes pressurized oil to the turbocharger center housing. The
recommended oil grade is SAE 30 or SAE 40, diesel-rated, API CF or
higher.
The cooling system is an indirect freshwater (closed) cooling design
with a separate seawater circuit. The freshwater circuit is sealed,
pressurized, and thermostatically controlled. A centrifugal fresh water
pump, driven by the timing gear train, circulates coolant through the
cylinder block water jacket, cylinder head, turbocharger center housing,
and the tube side of a tubular heat exchanger.
A wax-pellet thermostat, rated to begin opening at 80°C (176°F),
regulates coolant temperature. When the thermostat is closed, coolant
recirculates within the engine for rapid warm-up. When open, coolant
flows through the heat exchanger. The seawater circuit uses a
belt-driven or engine-mounted rubber-impeller raw water pump. This pump
draws seawater through a hull inlet and strainer and then pumps it
through the shell side of the heat exchanger, absorbing heat from the
freshwater coolant.
From the heat exchanger, seawater is optionally routed through the
intercooler (charge air cooler) before being injected into the exhaust
mixing elbow to cool exhaust gases prior to overboard discharge. The
system includes a coolant recovery reservoir connected to the heat
exchanger filler neck. A galvanic corrosion protection system (zinc
anode) is installed in the heat exchanger to prevent electrolytic
damage.
| Intake and Exhaust Systems |
Intake System: Air enters through a dry-type air cleaner or a
low-restriction silencer, flows through the turbocharger compressor
inlet, then through the intercooler (air cooler) before entering the
cast-iron intake manifold. The manifold distributes charge air evenly to
all six cylinders.
Exhaust System: A water-cooled cast-iron exhaust manifold collects
exhaust gases from all six cylinders and routes them to the turbocharger
turbine housing inlet. From the turbocharger outlet, exhaust flows
through a flexible metal bellows section, a marine-grade silencer
(muffler), and a water-cooled mixing elbow where seawater is injected
for cooling before the exhaust gas is discharged through the hull.
Starting System: The engine is equipped with a turbine-type air motor
starting system. Compressed air from a receiver, stored at approximately
30 bar (435 psi), is directed to the air motor, which engages the
flywheel ring gear via a reduction gear. An air distributor valve
sequences air supply to the cylinders for initial firing. A manual
emergency stop valve is provided on the air supply line.
Electrical System: The engine is equipped with a 24-volt DC electrical
system for monitoring and control functions. A 24-volt, 30-50 ampere
alternator, driven by the front gear train, charges the starting
batteries and supplies power for engine instrumentation,
electro-pneumatic controls, and alarm systems. The electrical system is
IP55-rated for marine engine room environments.
Turbocharger System: A single, fixed-geometry turbocharger, sized for
the 750 rpm operating range, is mounted directly on the exhaust
manifold. Exhaust gas flow spins the turbine wheel, which drives the
compressor wheel on the same shaft. The compressor draws ambient air
through the air cleaner and compresses it, increasing air density and
enabling more fuel to be burned per cycle. The intercooler reduces the
temperature of the compressed air, further increasing its density and
improving combustion efficiency. The turbocharger center housing
includes both oil feed and return ports for bearing lubrication.
Control and Monitoring System: The engine is equipped with a local
control panel and remote monitoring system connections. Standard sensors
provide outputs for tachometer (magnetic pickup on flywheel housing),
coolant temperature (thermistor), oil pressure (strain gauge), exhaust
gas temperature (pyrometer at each cylinder outlet), and boost pressure.
An alarm system activates audible and visual warnings for low oil
pressure, high coolant temperature, high exhaust temperature, and low
starting air pressure.
Governor: An electronic speed governor (isochronous) or a mechanical
hydraulic governor is provided, depending on the vessel’s propulsion
control system. The governor maintains stable engine speed from low idle
to full rated load.
Overall Length (Front Pulley to Flywheel Housing End, A): 5,483 mm to
5,880 mm (215.9-231.5 in), depending on marine gear model (YXH-2000 or
YXH-2500 series, offset or coaxial configuration). Overall Width (B):
1,804 mm (71.0 in). Overall Height (From Crankshaft Centerline to Valve
Cover Top, C): 3,112 mm (122.5 in). Minimum Piston Removal Height (Oil
Pan to Top of Engine, G): 1,900 mm (74.8 in).
Dry Engine Weight (Complete, No Fluids, No Marine Gear): 18,500 kg
(40,785 lb). Total Unit Weight (Engine with YXH Series Marine Gear):
22,549 kg (49,700 lb) to 23,840 kg (52,560 lb).
Engine Oil:
Grade: SAE 30 or SAE 40 (diesel-rated, API CF, CF-4, or CG-4).
Capacity: As specified in engine operation manual (dependent on sump
configuration).
Normal Pressure (Rated Speed, Hot): 350-450 kPa (51-65 psi).
Minimum Pressure (Hot Idle): 70 kPa (10 psi).
Cooling System (Freshwater Circuit):
Coolant Type: Diesel-rated ethylene glycol antifreeze (50/50 mix with
distilled water).
Freshwater Capacity (Engine and Heat Exchanger): As specified in engine
operation manual.
Thermostat Opening Temperature: Approximately 80°C (176°F).
Heat Exchanger Pressure Cap Rating: 0.7-1.0 bar (10-15 psi).
Valve Adjustment Interval: Inspect and adjust every 1,000-1,500
operating hours or annually, whichever occurs first. Engine Oil Change
Interval: Change every 500 operating hours or 6 months for commercial
service. Reduce to 250 hours for severe duty (frequent slow-speed
maneuvering, heavy fuel oil operation). Oil Filter Change Interval:
Replace at every oil change. Air Motor Starting System: Inspect air
motor starter and air distributor valve every 1,000 operating hours.
Lubricate with turbine oil as specified.
Fuel Filter Change Interval: Replace primary (water-separating) and
secondary fuel filters every 500 operating hours. Drain water from
primary filter daily. Coolant Change Interval: Drain, flush, and refill
every 2,000 operating hours or every 2 years. Injector Testing Interval:
Test injector opening pressure and spray pattern every 2,000 operating
hours. Recalibrate or replace as needed. Turbocharger Inspection:
Inspect shaft end-play and radial clearance every 3,000 operating hours.
The Yanmar 6EY26W engine is designed exclusively for marine propulsion
and is utilized as the primary diesel powertrain for the following
vessel types.
Commercial Fishing Vessels:
Trawlers, longliners, and purse seiners (75-120 ft length range).
Crab fishing vessels (including Project 5712LS crab catcher designs).
Combination fishing boats (gillnetter/troller configurations).
Workboats:
Harbor tugs and push boats (short-haul and harbor assist).
Crew transfer vessels for offshore wind farms and oil platforms.
Utility workboats for port maintenance and construction.
Passenger Vessels:
Small passenger ferries (coastal and inland waterway routes).
Tour boats and excursion vessels.
Water taxis (high-capacity configurations).
Cargo Vessels:
Small coastal freighters and landing craft.
General cargo vessels serving island and remote communities.
Other Applications:
Pump drive systems (irrigation and drainage pump stations using the EY26
series platform).
Emergency generator sets (6EY26LW series, a lower-speed variant for
genset applications).
Marine Gear Compatibility: Yanmar YXH-2000 series (for fixed-pitch
propellers F.P.P. with reduction ratios of 2.23, 2.58, 2.79, or 3.03
forward). Yanmar YXH-2500 series (for fixed-pitch propellers F.P.P. with
reduction ratios of 2.23, 2.58, 2.79, or 3.03 forward). YXH-2000M /
YXH-2500M series (for controllable-pitch propellers C.P.P. with
reduction ratios of 2.23, 2.58, 2.79, or 3.03 forward).
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