Yanmar 3JH3E Specifications
| Engine Model: Yanmar 3JH3E |
| Engine Type: 4-stroke inline 3-cylinder naturally aspirated water-cooled diesel |
| Total Displacement: 91.3 cu.in (1.49 L) |
| Rated Engine Power: 40 Hp (29.4 kW) at 3000 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 3JH3E is a 1.6-liter, naturally aspirated inline-three marine
diesel engine produced by Yanmar Co., Ltd. This engine is part of the
JH3 series, which introduced a larger displacement and more powerful
design compared to the older JH2 series. The Yanmar 3JH3E was engineered
as a compact, efficient, and highly reliable propulsion powerplant for
mid-sized sailing yachts, motorboats, and light commercial vessels.
The engine features a cast iron cylinder block, direct injection
combustion system, and a freshwater cooling system with a heat exchanger
for seawater isolation. The naturally aspirated design eliminates the
complexity of a turbocharger while delivering sufficient power for
displacement hulls and planning craft. The engine gained particular
popularity in catamaran applications, often paired with the SD40
saildrive unit. The 3JH3E meets IMO Tier II and US EPA Tier 2 emissions
standards, reflecting Yanmar's commitment to environmental compliance in
the recreational and commercial marine sectors.
Engine Type: Inline-3, four-stroke, vertical, water-cooled diesel.
Displacement: 1.496 L (91.3 cu.in).
Bore and Stroke: 84.0 mm x 90.0 mm (3.31 in x 3.54 in).
Compression Ratio: 22.0:1.
Combustion System: Direct injection.
Aspiration: Naturally aspirated.
Firing Order: 1-3-2.
Maximum Power: 29.4 kW (40 hp) at 3,000 rpm.
Continuous Rating: 26.5 kW (36 hp) at 3,000-3,650 rpm.
Maximum Torque: 109 Nm (80.4 lb-ft) at 3,000 rpm.
The cylinder block is constructed from high-strength cast iron, a
material selection providing the rigidity and vibration damping required
for sustained marine diesel operation. The block incorporates four main
bearing bulkheads supporting a forged or cast steel crankshaft. The
engine uses a replaceable wet-type cylinder liner design, a significant
advantage for marine applications where in-boat overhaul capability
reduces haul-out costs and downtime.
The block includes cast water jacket passages surrounding each cylinder
liner for uniform coolant distribution and thermal management. The block
also features integral engine mounting feet with adjustable
anti-vibration mounts to isolate the hull from engine vibrations.
The cylinder head is a single-piece cast iron unit that houses the
direct injection combustion chambers. Cast iron construction provides
the thermal mass and durability required for sustained marine diesel
operation. The head incorporates individual injector bores positioned
centrally above each piston for optimal fuel spray distribution. The
valve arrangement follows a parallel layout, with both intake and
exhaust valves aligned along the cylinder head centerline.
The valvetrain operates on an overhead valve (OHV) configuration with
pushrods and rocker arms. The camshaft is located within the cylinder
block and driven by a gear train from the crankshaft. Each cylinder
receives two valves: one intake and one exhaust. Hardened valve seat
inserts are pressed into the cylinder head and machined to precise
angles for positive sealing against diesel combustion pressures.
The rocker arm assembly is supported on a single shaft running the
length of the cylinder head. Individual screw-type adjusters with
locking nuts provide precise valve lash adjustment. The valve cover is a
stamped steel or cast aluminum component sealed by a gasket.
The fuel system employs a mechanical direct injection design. The
injection pump is a mechanically controlled in-line or distributor-type
pump driven by a gear from the camshaft. The direct injection system
delivers fuel at a pressure of 200 kg/cm2 through individual
high-pressure lines to injectors mounted in the cylinder head.
Each injector is of the nozzle-and-holder type, calibrated to open at a
precise pressure and deliver a finely atomized fuel spray pattern
directly into the combustion chamber formed in the piston crown. The
injector opening pressure of 200 kg/cm2 ensures complete fuel
atomization for efficient combustion and low exhaust emissions.
A fuel filter with an integrated water separator is mounted between the
fuel tank and the injection pump. This component is essential for marine
diesel systems, as water contamination from fuel storage can cause
corrosion and premature wear of the precision injection pump components.
The lubrication system is a fully pressurized, forced lubrication design
using a trochoid-type oil pump. The pump is mounted inside the oil pan
or on the front of the engine block and driven by the crankshaft gear
train. The trochoid pump design consists of an inner rotor with lobes
that mesh with an outer rotor, creating expanding and contracting
chambers that draw and discharge oil with minimal pulsation.
The full-flow spin-on oil filter is mounted on the cylinder block. As
all oil circulated by the pump passes through this filter before
reaching the bearing surfaces, any contaminants are removed from the
lubrication circuit during every pass. From the filter, oil circulates
through main oil galleries drilled longitudinally through the block,
supplying the crankshaft main bearings, connecting rod bearings,
camshaft bearings, and the valve train components. Oil capacity is 5.0 L
(5.3 US qt) for the total system, with an effective capacity of 2.1 L
(2.2 US qt) during normal circulation.
The cooling system is an indirect freshwater cooling design with a
tubular heat exchanger. This system configuration isolates the engine's
internal coolant circuit from the seawater environment, reducing
corrosion and scale formation within the engine. Freshwater coolant
circulates through the engine block, cylinder head, and the freshwater
side of the heat exchanger, while seawater circulated by a gear-driven
raw water pump passes through the seawater side of the heat exchanger to
remove heat.
A belt-driven freshwater circulation pump moves coolant within the
closed circuit. A wax-type thermostat maintains engine operating
temperature within the designed range, 82°C (180°F), allowing the engine
to reach optimal thermal efficiency quickly while preventing overheating
under sustained load. A water-cooled exhaust manifold reduces surface
temperatures in the engine compartment. An exhaust elbow injects
seawater into the exhaust stream to cool the exhaust gases before they
enter the rubber exhaust hose or underwater discharge.
| Intake and Exhaust Systems |
Air Intake System: A dry-type air cleaner with a replaceable paper
filter element is mounted on the intake side of the engine. Marine
installations often use a flame arrestor type air intake to prevent
backfire propagation in the engine compartment.
Exhaust System: The engine includes a water-cooled exhaust manifold. A
water-injected exhaust elbow introduces seawater into the exhaust
stream, cooling the gases to a temperature safe for flexible rubber
exhaust hose and underwater discharge.
The engine uses a 12-volt electrical system with negative ground. A
12-volt, 1.4 kW starter motor engages the flywheel ring gear for engine
cranking. The alternator is available in two outputs: a standard 12V-60A
unit or an optional 12V-80A unit. The higher-output alternator is
recommended for vessels with significant electrical loads including
refrigeration, navigation electronics, and windlasses.
Starting System: Electric start only. Glow plugs are installed for cold
starting assistance, pre-heating the combustion chambers to improve
ignition in cold conditions.
Timing System: The camshaft and injection pump are driven by a gear
train at the front of the engine. This gear drive system provides
precise timing without the maintenance or replacement concerns
associated with belt or chain drives.
Transmission Options: KM3A / KM3P: Mechanical cone clutch gearboxes with
forward ratios of 2.36 or 2.61. SD40 Saildrive: A popular combination
for catamarans and sailboats, offering a 2.49 reduction ratio and
integrated lower drive unit. SD20 / SD30 / SD31: Earlier saildrive
models compatible with the 3JH3E.
0The length ranges from 737 mm (29.0 in) to 830 mm (32.7 in). The width
ranges from 467 mm (18.4 in) to 543 mm (21.4 in). The height ranges from
608 mm (23.9 in) to 640 mm (25.2 in). Dry weight varies significantly
with the attached transmission. The base engine with KM3A gear weighs
186 kg (410 lb). With the KM3P gear, the dry weight is 227-242 kg
(500-533 lb). Some specifications report the bare engine weight as low
as 151 kg (333 lb).
Engine Oil Capacity: Total system 5.0 L (5.3 US qt); effective
circulation capacity 2.1 L (2.2 US qt).
Recommended Oil Viscosity: 15W-40 for temperate marine environments.
API Classification: CD, CE, or CF for diesel service.
Oil Change Interval: 250-500 operating hours, depending on service
conditions.
Coolant Capacity: 6.5 L (1.7 US gal / 6.9 US qt) for the freshwater
cooling circuit.
Coolant Type: Ethylene glycol antifreeze for diesel engines with
supplemental coolant additives.
Thermostat Opening Temperature: 82°C (180°F).
Valve Clearance Adjustment (Cold Engine): Intake and Exhaust 0.20 mm
(0.008 in).
Fuel Injection Pressure: 200 kg/cm2.
Idle Speed: 650-750 rpm in neutral.
Rated Speed Range: 3,000-3,800 rpm depending on load condition.
Fuel Filter Replacement Interval: 250-500 operating hours.
Raw Water Pump Impeller Replacement: Every 500 hours or annually,
whichever occurs first.
Heat Exchanger Service: Clean seawater side every 500-1,000 hours to
maintain cooling efficiency.
Valve Clearance Adjustment: Every 500-1,000 hours or as indicated by
increased engine noise.
Injector Inspection Interval: Every 1,000 operating hours.
Connecting Rod Bolts: 36-40 lb-ft (49-54 Nm / 5.0-5.5 kgm).
Connecting Rod Cap Nuts: 6-7 kgm (43-51 lb-ft / 58-69 Nm).
Main Bearing Cap Bolts: 50-60 lb-ft (68-81 Nm).
Flywheel Bolts: 40-45 lb-ft (54-61 Nm).
Crankshaft Pulley Bolt: 100-120 lb-ft (136-163 Nm).
Rocker Arm Shaft Bracket Bolts: 18-22 lb-ft (24-30 Nm).
Camshaft Thrust Plate Bolts: 15-18 lb-ft (20-24 Nm).
Intake Manifold Nuts: 18-22 lb-ft (24-30 Nm).
Exhaust Manifold Nuts: 18-22 lb-ft (24-30 Nm).
Injector Hold-Down Clamp Bolts: 18-22 lb-ft (24-30 Nm).
Injection Pump Mounting Nuts: 15-18 lb-ft (20-24 Nm).
Glow Plug Torque: 10-12 lb-ft (14-16 Nm).
Oil Pan Bolts: 7-9 lb-ft (10-12 Nm).
Valve Cover Bolts: 4-5 lb-ft (5-7 Nm).
Water Pump Mounting Bolts: 14-18 lb-ft (19-24 Nm).
Starter Motor Mounting Bolts: 25-30 lb-ft (34-41 Nm).
Alternator Mounting Bolts: 25-30 lb-ft (34-41 Nm).
Engine Mounting Bolts: 50-60 lb-ft (68-81 Nm).
The Yanmar 3JH3E engine was installed in marine vessels across
recreational, commercial, and light industrial segments from
approximately 2000 through 2010.
Sailing Yachts: The 3JH3E is a common auxiliary powerplant for mid-sized
cruising sailboats between 36-46 ft (11-14 m) in length. The engine
provides reliable propulsion for maneuvering in harbors and powering
when wind conditions are unfavorable.
Catamarans: The 3JH3E gained particular popularity in catamaran
applications, including Fountaine-Pajot models. Catamarans often install
twin 3JH3E engines, one in each hull, providing redundant propulsion and
improved maneuverability. These installations are frequently paired with
SD40 saildrives.
Motorboats: Small to mid-sized motor cruisers and trawlers use the 3JH3E
for its fuel efficiency and reliability.
Light Commercial Vessels: Small workboats, pilot vessels, and passenger
launches have been equipped with the 3JH3E, particularly in European and
Asian markets where fuel efficiency and emissions compliance are
prioritized.
Transmission Configurations: Shaft Drive (KM3A/KM3P): Mechanical cone
clutch gearboxes mounted directly to the engine flywheel housing,
driving a conventional propeller shaft. Saildrive
(SD20/SD30/SD31/SD40/SD50): A compact lower drive unit that mounts
through the vessel's hull, reducing the shaft angle and improving
propeller efficiency. The SD40 saildrive is particularly common with the
3JH3E.
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