Yanmar 3YM30AE Specifications
| Engine Model: Yanmar 3YM30AE |
| Engine Type: 4-stroke inline 3-cylinder water-cooled diesel |
| Total Displacement: 77.2 cu.in (1.27 L) |
| Rated Engine Power: 29 Hp (21.3 kW) at 3200 rpm |
| Fuel System Type: Indirect injection |
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The Yanmar 3YM30AE is a vertical, 3-cylinder,
4-stroke, water-cooled marine diesel engine introduced around 2014 as an
upgraded iteration of the 3YM30. The "AE" designation reflects increased
displacement and compliance with stricter emission regulations,
specifically US EPA Tier 3. This engine remains mechanically governed
and naturally aspirated, distinguishing it from electronically
controlled marine diesels. The Yanmar 3YM30AE is engineered for
auxiliary propulsion in sailboats and power vessels up to 35 feet (10.7
m) in length, offering a balance of reduced vibration, fuel efficiency,
and emission compliance.
The Yanmar 3YM30AE is a naturally aspirated, 3-cylinder, 4-stroke marine
diesel engine using indirect injection via a swirl pre-combustion
chamber. Displacement is 1.266 L. The engine features a cast iron
cylinder block and an aluminum alloy cylinder head. The valvetrain is an
overhead valve pushrod design with 2 valves per cylinder (6 valves
total). Cooling is provided by a freshwater closed-loop system with a
heat exchanger and a belt-driven raw water pump. Lubrication is a
forced-feed system with a trochoid-type oil pump. The engine includes a
12 V electric starter (1.4 kW) and a 125 A alternator.
Engine Type: Vertical, inline 3-cylinder, 4-stroke, water-cooled,
naturally aspirated diesel
Displacement: 1.266 L (1266 cc / 77.2 cu.in)
Bore: 80.0 mm (3.15 in)
Stroke: 84.0 mm (3.31 in)
Compression Ratio: 23.0:1
Maximum Crankshaft Power: 21.3 kW (29 hp) at 3200 rpm
Continuous Rating: 18.4 kW (24.7 hp) at 3089 rpm
Maximum Torque: 75.0 Nm (55.3 lb-ft) at 2000-2400 rpm
Cruising RPM Range: 2500 rpm to 2900 rpm
Firing Order: 1-2-3
Rotation (viewed from flywheel): Counterclockwise
Combustion System: Indirect injection with swirl pre-combustion chamber
Aspiration: Naturally aspirated
Emission Compliance: US EPA Tier 3, RCD 2
The cylinder block is manufactured from grey cast iron as a monobloc
casting. The block is a deep-skirt design with integral water jackets
surrounding all three cylinder bores. The parent cylinder bores are
machined directly into the cast iron material without replaceable
liners. The block incorporates a built-in counterbalance shaft to reduce
the inherent vibration of a 3-cylinder inline configuration.
The crankcase is rigid with five main bearing webs supporting the
crankshaft. The block includes an integral oil gallery supplying the
main bearings and the camshaft. Mounting feet for the engine beds are
cast into the lower portion of the block. The oil dipstick tube and oil
filler neck are positioned on the port or starboard side depending on
installation orientation.
Crankshaft: The crankshaft is forged from carbon steel with five main
bearing journals and three connecting rod journals. A torsional
vibration damper is fitted to the front end. The flywheel is bolted to
the rear flange. Connecting Rods: Forged steel I-beam design with
replaceable bearing shells at the big end. The small end is bushed with
a bronze alloy. Pistons: Cast aluminum alloy with a shallow combustion
bowl. Three piston rings per cylinder: two compression rings (top ring
chromed) and one oil control ring with an expander.
The cylinder head is a single casting manufactured from aluminum alloy
to reduce overall engine mass. The head contains three swirl
pre-combustion chambers (indirect injection system), each fitted with a
steel insert forming an ante-chamber where combustion initiates before
expanding into the main cylinder. The overhead valve arrangement uses a
pushrod actuation system with a camshaft positioned within the cylinder
block.
Each cylinder has two valves: one intake valve and one exhaust valve (6
valves total). Valve stems are sealed with rubber stem seals on both
intake and exhaust. The rocker arm assembly is mounted on a single
shaft, with adjustable screw and locknut for valve lash setting. Valve
clearances are identical for intake and exhaust at 0.20 mm (0.008 in)
cold.
The fuel system is an indirect injection architecture using a swirl
pre-combustion chamber. A mechanical inline injection pump, mounted to
the side of the cylinder block, is driven by the camshaft. The pump
contains three plungers and barrels. A mechanical centrifugal governor
maintains engine speed under varying loads. A diaphragm-type fuel feed
pump with a manual primer lever draws fuel from the tank through a
primary water-separating filter. High-pressure injection lines of equal
length connect the pump to the injectors.
Each injector is a pintle type, installed into the cylinder head and
spraying fuel into the pre-combustion chamber insert. The injection
pressure is set to 11.8 MPa to 12.8 MPa (1707 psi to 1849 psi). Excess
fuel returns to the tank via a common leak-off line. Bleeding of air
from the system is achieved using the manual primer lever and a bleed
screw on the injection pump.
The lubrication system is a forced-feed, wet-sump design. A
trochoid-type oil pump is mounted on the timing gear cover and driven by
the camshaft. The pump draws oil through a suction strainer positioned
in the lower crankcase. Oil passes through a spin-on full-flow filter
mounted externally on the engine block.
A pressure relief valve maintains system pressure. The total oil
capacity is 2.8 L (3.0 qt). The recommended oil classification is API
CD, CE, CF, CF-4, or CG-4 with SAE 10W-30, 15W-40, or 5W-30 depending on
ambient temperature. An optional oil change pump can be installed for
remote extraction.
0The cooling system is a freshwater closed-loop circuit with a heat
exchanger. The internal circuit circulates a glycol-based antifreeze
mixture through the cylinder block, cylinder head, and a tubular heat
exchanger. A belt-driven centrifugal fresh water pump circulates the
internal coolant. A wax-pellet thermostat located in the freshwater
outlet housing begins opening at 71°C (160°F) and achieves full lift at
85°C (185°F).
The external raw water circuit is drawn from the surrounding body of
water by a flexible-impeller pump (rubber impeller) driven by the same
belt. Raw water passes through the heat exchanger tubes, absorbing heat
from the fresh water, then is injected into the exhaust elbow to cool
exhaust gases. The heat exchanger is a shell-and-tube design with a zinc
sacrificial anode to prevent galvanic corrosion. Coolant capacity is 4.3
L (4.5 qt).
Timing Drive: A silent timing chain drives the camshaft from the
crankshaft. An automatic hydraulic chain tensioner maintains proper
chain slack. The injection pump and oil pump are driven by gears from
the camshaft.
Starting System: 12 V electric starter motor rated at 1.4 kW, engaging a
ring gear on the flywheel. Pre-heat is provided by glow plugs in each
pre-combustion chamber for cold starting.
Charging System: 12 V alternator rated at 125 A standard. The alternator
is belt-driven from the crankshaft pulley.
Exhaust System: A water-cooled exhaust elbow injects raw water into the
exhaust stream before discharge through a gooseneck fitting and
below-waterline exhaust outlet.
Marine Gear Options: KM2P-1A Reverse Gear: Mechanical cone clutch.
Reduction ratios: 2.21:1, 2.62:1, or 3.06:1. KM2A-1 Reverse Gear:
Hydraulic cone clutch for smoother engagement. Reduction ratios: 2.21:1,
2.62:1, or 3.06:1. SD25 Saildrive: Constant mesh gear with dog clutch,
reduction ratio 2.64:1. Designed to mount through the hull.
Length (engine only): 624 mm (24.6 in) from front pulley to flywheel
housing
Length (with KM2P-1A gear): 740 mm (29.1 in)
Width (engine only): 480 mm (18.9 in) at rocker cover
Height (engine only): 530 mm (20.9 in) from oil pan rail to rocker cover
Dry Weight (engine only, without gearbox): 127 kg (280 lb)
Dry Weight (with KM2P-1A gear): 137 kg (302 lb)
Dry Weight (with SD25 saildrive): 160 kg (353 lb)
Engine Oil Capacity (with filter): 2.8 L (3.0 qt)
Oil Grade: SAE 10W-30 or 15W-40 meeting API CD, CE, CF, CF-4, or CG-4
Coolant Capacity (freshwater circuit): 4.3 L (4.5 qt)
Coolant Specification: Ethylene glycol antifreeze with corrosion
inhibitor
Raw Water Pump Impeller Replacement Interval: 200 hours or annually
Valve Clearance (cold): Intake 0.20 mm (0.008 in); Exhaust 0.20 mm
(0.008 in)
Valve Clearance Adjustment Interval: 500 hours or as needed
Injection Pressure Setting: 11.8-12.8 MPa (1707-1849 psi)
Injection Timing: 16° BTDC (static, measured at injection pump)
Glow Plug Operation: Pre-heat for 5 to 10 sec before starting below 10C
(50F)
Oil Change Interval (normal service): 250 hours or annually
Oil Filter Replacement Interval: 250 hours (at each oil change)
Fuel Filter (primary) Replacement: 250 hours
Fuel Filter (secondary) Replacement: 500 hours
Timing Chain Inspection: 1000 hours; replace if slack exceeds
specification
Idle Speed (in neutral): 750 rpm to 800 rpm
Thermostat Opening Temperature: 71C (160F) starts opening; 85C (185F)
fully open
Compression Pressure (minimum): 2.8 MPa (406 psi) at cranking speed
Compression Pressure Difference Between Cylinders: Maximum 10%
Cylinder Head Bolts (M10), Stage 1: 25 Nm (18 lb-ft)
Cylinder Head Bolts (M10), Stage 2: 50 Nm (37 lb-ft)
Cylinder Head Bolts (M10), Stage 3: 80 Nm (59 lb-ft).
Main Bearing Cap Bolts: 55 Nm (41 lb-ft)
Connecting Rod Cap Nuts: 32 Nm (24 lb-ft)
Crankshaft Pulley Bolt (center): 100 Nm (74 lb-ft)
Flywheel Bolts (to crankshaft): 50 Nm (37 lb-ft)
Rocker Arm Shaft Support Bolts: 20 Nm (15 lb-ft)
Rocker Arm Adjuster Locknut: 10 Nm (7 lb-ft)
Injection Pump Mounting Nuts: 18 Nm (13 lb-ft)
Injector Clamp Bolt: 20 Nm (15 lb-ft)
Injector Nozzle Nut (internal): 40 Nm (30 lb-ft)
Intake Manifold Bolts: 18 Nm (13 lb-ft)
Exhaust Manifold Nuts: 18 Nm (13 lb-ft)
Glow Plug Holder Torque: 15 Nm (11 lb-ft)
Oil Pan Bolts: 12 Nm (9 lb-ft)
Oil Filter (spin-on): 12 Nm (9 lb-ft)
Starter Motor Mounting Bolts: 30 Nm (22 lb-ft)
Alternator Mounting Bracket Bolts: 25 Nm (18 lb-ft)
Heat Exchanger End Cover Bolts: 8 Nm (6 lb-ft)
Engine Mounting Bolts (to bed): 60 Nm (44 lb-ft)
The Yanmar 3YM30AE is installed as auxiliary propulsion in a range of
marine vessels.
Sailboats (up to 35 ft / 10.7 m LOA):
Bavaria 32.
Beneteau Oceanis 321.
Catalina 309.
Dufour 325.
Elan 310.
Hanse 311.
Hunter 31.
Jeanneau Sun Odyssey 32.
Moody 31.
Westerly 33.
Powerboats and Motor Cruisers:
Small displacement cruisers up to 9 m (30 ft).
Daysailers.
Downeast-style workboats.
Drive Configurations: KM2P-1A Mechanical Reverse Gear: Standard
propeller shaft drive for vessels needing a low-cost, reliable
mechanical gearbox. KM2A-1 Hydraulic Reverse Gear: Smoother shifting for
vessels where gear engagement noise or shock is a concern. SD25
Saildrive: Low-profile saildrive unit for sailing yachts, reducing
vibration and eliminating shaft angle alignment requirements.
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