Yanmar 6EY18ALW Specifications
| Engine Model: Yanmar 6EY18ALW |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 2,608 cu.in (42.74 L) |
| Rated Engine Power: 748-1,088 Hp (550-800 kW) at 720-1000 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 6EY18ALW is a medium-speed, 4-stroke
marine diesel engine specifically engineered as an auxiliary power unit
for generator set applications aboard commercial vessels. This engine
belongs to the EY18 series, recognized for low fuel consumption,
extended service intervals, and compliance with IMO Tier II emissions
standards without requiring selective catalytic reduction or exhaust gas
recirculation systems.
The Yanmar 6EY18ALW serves as the higher-rated variant within the 6EY18
line, achieving generator outputs up to 750 kWe through increased rated
speeds of 900 or 1,000 rpm. Marine architects specify this engine for
tankers, bulk carriers, container ships, offshore support vessels, and
fishing fleets where auxiliary power reliability directly impacts cargo
handling, refrigeration, navigation, and hotel loads.
The engine's robust construction with 180 mm bore and 280 mm stroke
delivers a displacement of 42.74 Liters across six cylinders, providing
the thermal margin necessary for sustained high-load factor operation
common in marine generator duty. Operators value the 6EY18ALW for its
compatibility with both heavy fuel oil and marine diesel oil, allowing
fuel flexibility based on regional availability and operational
economics.
Engine Model: 6EY18ALW.
Engine Type: 4-stroke, vertical, water-cooled diesel engine.
Cylinder Configuration: 6-cylinder in-line.
Bore x Stroke: 180 mm x 280 mm (7.09 in x 11.02 in).
Displacement: 42.74 Liters (2,608 cu.in).
Rated Engine Output Range: 550 kW to 800 kW (748 HP to 1,088 HP).
Generator Capacity Range: 400 kWe to 750 kWe at 0.8 power factor.
Rated Speeds: 720, 750, 900, or 1,000 rpm.
Frequency: 50 Hz at 750 or 1,000 rpm with 6-pole or 4-pole generators.
Frequency: 60 Hz at 720 or 900 rpm with 8-pole or 6-pole generators.
Mean Effective Pressure: 1.28-2.25 MPa (186-326 psi) across the
operating range.
Direction of Rotation: Clockwise when viewed from the flywheel side.
Combustion System: Direct injection with fuel injected directly into the
combustion chamber formed in the piston crown.
Aspiration: Turbocharged with intercooler using
an exhaust gas turbine driving a compressor wheel, with compressed air
passing through a seawater-cooled air cooler before entering the intake
manifold.
The cylinder block is constructed from high-grade cast iron with a rigid
monobloc design incorporating integrated cooling water jackets
surrounding each cylinder bore. The block architecture features
individual cylinder heads rather than a single head casting, allowing
each cylinder to be serviced independently without disturbing adjacent
cylinders. Wet-type replaceable cylinder liners are manufactured from
centrifugally cast alloy iron with a hardened internal bore surface
achieved through induction hardening or chromium plating.
Each liner incorporates O-ring seals at the lower end and a fire ring at
the upper flange to isolate combustion gases from the cooling water
circuit. The liner flange sits flush with the block deck surface,
transferring clamping loads from the cylinder head directly to the
liner. The block incorporates seven main bearing bulkheads with studded
cap retention, providing crankshaft support appropriate for the 280 mm
stroke and cylinder pressures generated at 2.25 MPa mean effective
pressure. Main bearing caps are cross-bolted on the center five
positions, with horizontal bolts passing through the cap into the block
side walls to increase lateral rigidity.
A cast-in oil gallery runs the full length of the block, distributing
pressurized lubricant to each main bearing through drilled passages,
with additional galleries feeding piston cooling jets and camshaft
bearings. The camshaft is located on the side of the block, driven by a
gear train from the crankshaft front end, with roller followers
actuating pushrods to overhead valve gear. Engine mounting feet are cast
integrally with the block at four positions designed for resilient
mounting on ship foundations.
The cylinder head arrangement uses individual heads per cylinder rather
than a single multi-cylinder casting. Each head is a separate cast-iron
component bolted to the block with four studs arranged around the
cylinder bore. The cross-flow port configuration positions intake valves
on the side facing the turbocharger and air cooler, with exhaust valves
on the opposite side directing gases to the exhaust manifold. Each
cylinder head contains two intake valves and two exhaust valves arranged
symmetrically around the centrally located fuel injector.
Intake valve diameter measures 52 mm (2.05 in) constructed from
chromium-silicon steel with induction-hardened stems. Exhaust valve
diameter measures 48 mm (1.89 in) manufactured from nickel-chromium
superalloy with Stellite-faced seating surfaces and sodium-cooled hollow
stems for heat dissipation. Valve seats are pressed-in powdered metal
inserts with interference fit of 0.05 mm to 0.08 mm (0.002 in to 0.003
in).
The overhead valve train incorporates roller rocker arms mounted on a
common shaft for each cylinder head, operating pushrods from the
camshaft-mounted roller followers. Valve clearances are adjustable using
screw-and-locknut adjusters at the rocker arm pushrod interface. Intake
valve clearance specification: 0.35 mm (0.014 in) cold. Exhaust valve
clearance specification: 0.45 mm (0.018 in) cold.
Valve rotators are installed on exhaust valves to promote even seat wear
by rotating the valve slightly each time it opens. Cylinder head gaskets
are multi-layer steel construction with embossed sealing beads and a
separate flame ring around the combustion chamber opening. Each cylinder
head incorporates a bronze valve guide insert that is replaceable when
clearance exceeds 0.15 mm (0.006 in) at the intake side or 0.20 mm
(0.008 in) at the exhaust side.
The fuel system is a direct injection design using an in-line jerk-type
injection pump mounted to the engine timing gear housing. The pump
contains six independent plunger and barrel assemblies, each driven by a
dedicated cam lobe on the pump camshaft. Plunger diameter measures 20 mm
with a 22 mm stroke, delivering injection pressure of 800 bar (11,600
psi) at rated load. Fuel injection timing is adjustable via shims
between the pump housing and the camshaft housing, with factory setting
at 12 degrees before top dead center at rated speed operation.
The governor is a hydraulic-mechanical all-speed type with isochronous
control for generator load sharing, maintaining speed regulation within
±5 percent from no-load to full-load. High-pressure injection lines
constructed from double-walled steel tubing with a burst containment
outer layer route fuel from the pump to each injector. Injectors are of
the multi-hole type with six nozzle holes, each hole diameter 0.28 mm,
producing a finely atomized fuel spray pattern directed into the piston
combustion bowl.
Injector opening pressure is set to 450 bar (6,525 psi) with a secondary
pressure adjustment provided by shim stack controlling needle spring
preload. The fuel supply system includes a feed pump, duplex filters
with 20-micron absolute rating, and a fuel heater for operation on heavy
fuel oil maintaining viscosity between 10 and 15 cSt at the injection
pump inlet. Fuel compatibility includes A-grade heavy fuel oil (JIS
Grade 1 Type 2 equivalent, cetane index not less than 45), marine diesel
oil, and marine gas oil.
The lubrication system uses a gear-type forced lubrication pump mounted
externally to the engine sump and driven by a gear train from the
camshaft. The pump draws oil from the deep-sump oil pan through a
suction strainer with 0.5 mm mesh openings, then delivers through an oil
cooler and full-flow filter before entering the main gallery. Oil pump
delivery capacity is 400 Liters per minute at rated speed, maintaining
main gallery pressure between 4.5 bar and 5.5 bar (65 psi to 80 psi) at
operating temperature.
Warm idle oil pressure is not less than 1.5 bar (22 psi). The oil cooler
is a tube-and-shell type using seawater as the cooling medium to
maintain oil temperature below 80°C (176°F) under full load. Filtration
is provided by a bank of two full-flow spin-on filters arranged in
parallel on a manifold with 15-micron absolute rating, plus a bypass
filter with 3-micron rating that processes 10 percent of oil flow.
Piston cooling jets are installed in the crankcase, each jet directing a
continuous stream of oil at the underside of each piston crown to manage
thermal loading at mean effective pressures up to 2.25 MPa.
The sump oil capacity is 220 Liters (58 U.S. Gal) for the engine with
standard oil pan. Oil specification requires API service classification
CE or CD grade with viscosity SAE 30 or SAE 40 for normal operation. For
cold ambient starting below 10°C (50°F), SAE 20 is permissible. Oil
change interval: 1,500 operating hours under normal marine generator
duty, reduced to 1,000 hours when operating on heavy fuel oil with high
sulfur content.
The cooling system uses a forced circulation fresh water circuit with
heat rejection to seawater through a separate heat exchanger. Fresh
water circulates through the cylinder block water jackets, cylinder
heads, and turbocharger housing, then passes through the tube side of
the heat exchanger where seawater flows on the shell side. Fresh water
circulation is provided by an externally mounted centrifugal pump with
electric motor drive, delivering 1,200 Liters per minute (317 U.S. Gal
per minute) at rated pump speed.
A wax-pellet thermostat located in the fresh water outlet maintains
jacket water temperature between 75°C and 85°C (167°F to 185°F), with
full opening at 82°C (180°F). A separate bypass circuit allows coolant
to circulate through the engine during warm-up before the thermostat
opens to the heat exchanger. The expansion tank is mounted at the
highest point of the system and includes a 1.0 bar (15 psi) pressure
cap.
Pressurization raises the boiling point to approximately 120°C (248°F),
preventing localized boiling at hot spots. Fresh water coolant capacity
for the engine and heat exchanger circuit is 150 Liters (40 U.S. Gal)
using ethylene glycol-based antifreeze at 30 to 40 percent concentration
for corrosion protection rather than freeze prevention in engine room
environments.
The seawater circuit draws raw water through a hull strainer, passes
through the charge air cooler first, then through the lubricating oil
cooler, and finally through the fresh water heat exchanger before
discharge overboard. Seawater flow rate is 2,500 Liters per minute (660
U.S. Gal per minute) provided by an engine-driven centrifugal pump. Zinc
sacrificial anodes are installed in the heat exchanger water boxes and
charge air cooler to prevent galvanic corrosion of cupronickel tubes.
| Intake and Exhaust Systems |
The air intake system incorporates a dry-type air filter with
replaceable cellulose element, followed by a rubber hose connecting to
the turbocharger compressor inlet. The turbocharger is a single-stage
unit with water-cooled bearing housing and a wastegate for overspeed
protection. The intercooler reduces intake air temperature from
approximately 180°C after compression to 45°C (356°F to 113°F) before
entry into the cylinder head intake ports.
The exhaust system includes a water-cooled exhaust manifold constructed
from cast iron with a jacketed design. Exhaust back pressure must not
exceed 4,900 Pa (0.71 psi) for standard conditions, reduced to 3,430 Pa
(0.50 psi) for pumping station or flood control applications. Exhaust
pipe diameter is 250 mm (10 in) nominal.
The air starting system uses compressed air at 30 bar (435 psi) supplied
from the ship's service air receiver. Air enters the starting valve on
each cylinder in firing order, with a distributor valve directing air to
each cylinder in sequence. Automatic safety interlocks prevent starting
if the turning gear remains engaged or if the starting air pressure
falls below 15 bar (218 psi). An electric starting motor (24 V DC) is
available as an alternative for installations without an onboard
compressed air system.
The governor system is a hydraulic isochronous type with load sensing
proportional to engine speed deviation. For parallel generator
operation, an additional load sharing module provides droop control
adjustable between 0 and 5 percent speed reduction from no-load to
full-load. A solenoid-operated shutdown system triggers on low oil
pressure, high coolant temperature, or engine overspeed exceeding 1,150
rpm.
Engine dry weight: 8,300 kg (18,298 lb) for the 6EY18ALW configuration
without generator attachment. Complete generator set dry weight: 11,200
kg to 12,100 kg (24,692 lb to 26,676 lb) depending on generator
manufacturer and specifications.
Overall length: 4,391 mm (173.0 in) for lower-rated models, extending to
4,680 mm (184.3 in) for higher-rated configurations. Overall width:
1,489 mm (58.6 in) measured across the widest points of the engine and
attached systems. Overall height: 3,115 mm (122.6 in) from the bottom of
the oil pan to the top of the cylinder head or turbocharger.
Piston removal clearance: 1,950 mm (76.8 in) required above the
crankshaft centerline to extract pistons and connecting rods upward.
Crankshaft centerline to oil pan rail: 350 mm (13.8 in).
Oil and filter change interval: 1,500 operating hours for standard
diesel operation, 1,000 hours for heavy fuel oil service. Oil filter
replacement at every oil change with 15-micron elements. Valve clearance
inspection interval: 1,000 hours with adjustment required if outside
tolerances. Intake valve clearance: 0.35 mm (0.014 in) cold. Exhaust
valve clearance: 0.45 mm (0.018 in) cold. Cylinder liner wear
measurement: 4,000 hours with service limit of 0.30 mm (0.012 in)
increase above standard bore diameter of 180.00 mm.
Fuel filter replacement interval: 500 hours for primary and secondary
filters. Water separator draining required every 100 hours or when
visible water accumulates. Cooling system service: Fresh water coolant
replacement every 2,000 hours or two years. Seawater pump impeller
inspection every 2,000 hours. Zinc anode replacement every 1,000 hours
or when 50 percent depleted. Main bearing clearance inspection: 4,000
hours with service limit of 0.20 mm (0.008 in).
Air filter element cleaning: 500 hours by reverse-flow compressed air.
Replacement required every 1,500 hours. Injector nozzle inspection:
2,000 hours with opening pressure verification at 450 bar (6,525 psi)
and spray pattern evaluation. Nozzle replacement recommended at 4,000
hours. Turbocharger bearing inspection: 4,000 hours with shaft axial
play not to exceed 0.10 mm (0.004 in) and radial clearance not to exceed
0.15 mm (0.006 in). Governor oil level check: 500 hours using same
specification as engine lubricating oil.
Cylinder head stud nuts: 480 Nm (354 lb-ft).
Connecting rod cap bolts: 450 Nm (332 lb-ft).
Main bearing cap bolts (vertical bolts): 800 Nm (590 lb-ft).
Main bearing cap bolts (horizontal cross-bolts): 500 Nm (369 lb-ft).
Flywheel to crankshaft bolts: 650 Nm (479 lb-ft).
Flywheel housing to cylinder block: 220 Nm (162 lb-ft)..
Injection pump mounting nuts: 80 Nm (59 lb-ft).
Injector hold-down clamp nut: 100 Nm (74 lb-ft).
High-pressure fuel line nuts: 50 Nm (37 lb-ft).
Rocker arm shaft pedestal bolts: 120 Nm (89 lb-ft).
Valve cover nuts: 25 Nm (18 lb-ft).
Oil pan bolts: 45 Nm (33 lb-ft).
Water pump mounting bolts: 90 Nm (66 lb-ft).
Seawater pump mounting bolts: 70 Nm (52 lb-ft).
Starter motor or air motor mounting bolts: 150 Nm (111 lb-ft).
Turbocharger mounting nuts: 100 Nm (74 lb-ft).
Exhaust manifold nuts: 160 Nm (118 lb-ft).
Engine mounting isolator to block: 350 Nm (258 lb-ft).
Camshaft bearing cap bolts: 90 Nm (66 lb-ft).
The Yanmar 6EY18ALW serves as a diesel generator drive engine for marine
auxiliary power applications rather than propulsion. Primary
installations include cargo ships such as container vessels, bulk
carriers, and tankers where generator sets supply power for
refrigeration, cargo pumps, ballast systems, and deck machinery.
Offshore support vessels including platform supply ships, anchor
handling tugs, and crew boats utilize the 6EY18ALW for station keeping
thrusters and dynamic positioning systems.
Fishing vessel applications include factory trawlers and longliners
where electrical power supports freezing equipment, fish processing
lines, and refrigeration holds. Passenger vessels such as ferries and
small cruise ships use these engines for hotel loads including lighting,
air conditioning, galley equipment, and desalination units. The engine
also appears in stationary power generation for ports, shipyards, and
coastal industrial facilities where marine-grade reliability is
required.
Each vessel configuration employs either one or multiple generator sets
operating in parallel, with typical installations using two to four
6EY18ALW units of identical rating for load sharing and redundancy. A
documented vessel installation includes a 61.80 m Norwegian longliner
operating with two 6EY18ALW generators each producing 800 kW (1,088 HP)
at 900 rpm, powering the vessel's freezing plant and hotel services
while the main propulsion engine handles transit.
Another installation in a 50,000 DWT product chemical tanker uses
6EY18ALW generators rated at 720 kW each at 900 rpm, validated through
factory acceptance testing before shipboard integration. Marine
classification society approvals include Lloyd's Register, DNV GL,
Bureau Veritas, American Bureau of Shipping (ABS), Class NK, and Kr.
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