Yanmar 4JH80 Specifications
| Engine Model: Yanmar 4JH80 |
| Engine Type: 4-stroke inline 4-cylinder turbocharged water-cooled diesel |
| Total Displacement: 122 cu.in (1.99 L) |
| Rated Engine Power: 80 Hp (58.8 kW) at 3200 rpm |
| Fuel System Type: Common rail direct injection |
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The Yanmar 4JH80 is a vertical, four-cycle,
four-cylinder marine diesel engine that utilizes common-rail fuel
injection and turbocharging to achieve high power output from a compact
displacement. Part of Yanmar’s modern JH-CR series, this engine features
full electronic control and meets stringent EPA Tier 3 and EU RCD2
emission standards. The Yanmar 4JH80 represents a significant
advancement over previous JH series engines, introducing Bosch common
rail technology that allows precise electronic control of injection
timing, fuel quantity, and injection pressure.
This results in reduced noise, lower emissions, improved fuel economy,
and higher torque across the operating range compared to mechanically
injected predecessors. The engine shares mounting dimensions with
earlier JH models, simplifying repower installations. Yanmar offers the
4JH80 for both leisure and light commercial applications, including
sailboats, catamarans, and small motor yachts. The engine carries
approvals for RCD 2, EPA Tier 3, BSO II, EMC, and SOLAS, with a
certified lifeboat option available.
The Yanmar 4JH80 is a four-cycle, water-cooled, inline four-cylinder
diesel engine with direct injection employing a Bosch common rail
system. The cylinder bore measures 84.0 mm (3.31 in), while the piston
stroke extends to 90.0 mm (3.54 in), creating an undersquare
configuration that favors torque production in the mid-range. Total
displacement is 1,995 cc (1.995 L / 122 cu.in). The combustion system is
direct injection with a Bosch common rail system operating at injection
pressures up to 1,600 bar (23,206 psi).
Aspiration is turbocharged and intercooled, with an air-to-air
aftercooler fitted to reduce intake air temperature. Maximum crankshaft
output is 58.8 kW (80 hp) at 3,200 rpm. Continuous rating is 53.5 kW
(72.8 hp) at 3,106 rpm. Maximum torque reaches 240 Nm (177 lb-ft / 24.5
kgm) at 1,800-2,200 rpm. Low idle speed is set to 750 rpm. The direction
of rotation, viewed from the flywheel, is counter-clockwise.
The cylinder block is constructed from cast iron, providing the rigidity
required for sustained high-load marine operation under turbocharged
conditions. The block features a conventional inline-four configuration
with cylinders cast directly into the iron matrix. Unlike larger marine
diesels, the 4JH80 does not utilize replaceable wet cylinder liners; the
bores are machined directly into the block casting.
The cylinder bore surface is hardened through a plateau honing process.
The block incorporates five main bearing bulkheads supporting the
crankshaft. An oil gallery is drilled along the right side of the block
to supply pressurized oil to the main bearings, camshaft bearings, and
rocker arm assembly. The water jacket surrounds the cylinders and
extends upward to the block deck. The engine number is stamped on a
machined pad located on the cylinder block.
The cylinder head is manufactured from cast iron, providing thermal
stability and resistance to warpage under the elevated cylinder
pressures produced by turbocharging and common rail injection. The head
employs an overhead valve (OHV) configuration with two valves per
cylinder, for a total of eight valves. The valvetrain is actuated by a
camshaft located within the cylinder block, driving pushrods and rocker
arms. The intake valve head diameter measures 36.0 mm (1.42 in), while
the exhaust valve diameter is 32.0 mm (1.26 in).
Valve stems are 7.0 mm (0.276 in) in diameter and are chrome-plated for
wear resistance. The cylinder head features pressed-in replaceable valve
guides. Valve seat inserts are induction-hardened for intake ports and
made of heat-resistant alloy for exhaust ports. Valve lash is adjusted
with the engine cold. Both intake and exhaust valve clearances are set
to 0.20 mm (0.008 in). The cylinder head gasket is a multi-layer steel
(MLS) design. Ten cylinder head bolts retain the head to the block.
The fuel system employs direct injection with a Bosch common rail
system, a significant departure from previous mechanically injected JH
series engines. A gear-type supply pump draws fuel from the tank through
a primary filter with a water separator and delivers it to the
high-pressure pump at 4-6 bar (58-87 psi).
The high-pressure pump, driven by the engine timing gear, pressurizes
fuel to up to 1,600 bar (23,206 psi) and delivers it to the common rail
accumulator. A fuel rail pressure sensor and pressure relief valve
maintain stable rail pressure. Electronic unit injectors, controlled by
the Engine Control Unit (ECU), meter precise fuel quantities with pilot
injection capability for reduced combustion noise.
The fuel system operates with a secondary spin-on filter of 2-micron
rating. Fuel injection timing and duration are fully variable under ECU
control, eliminating manual timing adjustment. The engine is approved
for use with HVO (Hydrotreated Vegetable Oil) as a drop-in fuel. A hand
primer pump on the filter head allows system priming after filter
replacement.
The lubrication system is a fully pressurized, wet-sump design using
forced lubrication with a trochoid pump and an oil cooler. The oil pump
is driven directly by the crankshaft and is mounted inside the oil pan.
Oil pressure at rated engine speed (3,200 rpm) is maintained between 40
and 60 psi (276 and 414 kPa). Total oil capacity, including the oil
filter, is 7.0 L (7.4 U.S. qt). A spin-on full-flow oil filter is
mounted to the engine block. The system incorporates a bypass valve that
opens at 25 psi (172 kPa) differential pressure if the filter becomes
restricted.
A water-to-oil heat exchanger, integrated into the engine block,
maintains oil temperature under sustained high-load operation. The oil
pan is constructed from stamped steel. A dipstick is located on the
right side of the block. Recommended oil viscosity is SAE 15W-40 meeting
API CK-4 or higher diesel rating. The engine is equipped with piston
cooling jets directed at the underside of each piston crown.
The cooling system is a pressurized, freshwater (closed) cooling design
with a belt-driven centrifugal fresh water pump. The pump circulates
coolant through the cylinder block, cylinder head, and a tubular heat
exchanger. A seawater pump, utilizing a rubber-impeller design, draws
seawater through a strainer and circulates it through the heat
exchanger, oil cooler, and exhaust mixing elbow. Coolant capacity for
the fresh water side, including the engine and heat exchanger, is 7.2 L
(7.6 U.S. qt).
A wax-pellet thermostat, rated at 76-82°C (169-180°F), controls coolant
flow to the heat exchanger. A bypass circuit allows coolant circulation
inside the engine when the thermostat is closed. An expansion tank is
integrated into the heat exchanger assembly. The seawater pump impeller
requires inspection every 200 hours. Coolant recommendations call for a
50/50 mixture of ethylene glycol antifreeze and distilled water.
| Intake and Exhaust Systems |
Air Intake System: The air intake system is turbocharged with a
fixed-geometry turbocharger and an air-to-air intercooler mounted on the
engine. Boost pressure ranges from 15 to 20 psi (103 to 138 kPa)
depending on load. The air cleaner is a dry-type paper element unit.
Exhaust System: The exhaust manifold is a single-piece, cast iron
water-cooled design. Seawater is injected into the exhaust elbow after
the turbocharger to cool exhaust gases. A U-type mixing elbow is
standard equipment.
The electrical system operates at 12 volts. The starter motor is a
gear-reduction type with a solenoid-actuated pinion engaging the
flywheel ring gear. Starter motor power rating is 1.4 kW (1.9 hp). The
alternator is a brushless, internally regulated unit rated at 125
amperes. Glow plugs are installed in each cylinder for cold start
assistance, with automatic ECU control of pre-heat and post-heat cycles.
Electronic Control System: The engine is controlled by an electronic
control unit (ECU) mounted directly on the engine. The ECU manages fuel
injection timing, injection pressure, idle speed, and provides engine
protection functions including overspeed shutdown, low oil pressure
warning, and high coolant temperature alarm. An optional NMEA 2000
gateway allows display of engine parameters on navigation screens. A
mechanical control option is available as standard, with the optional
VC10 electronic vessel control system offering up to three control
stations.
The complete engine dry weight without transmission is 229 kg (505 lb).
Overall length including the KM4A2 marine gear is 909 mm (35.8 in).
Maximum width is 613 mm (24.1 in). Height is 675 mm (26.6 in).
Dimensions may vary with different transmission selections and exhaust
elbow configurations.
Engine oil and oil filter change intervals are recommended every 250
operating hours or annually, whichever occurs first. The seawater pump
impeller requires inspection every 200 hours and replacement every 500
hours. The fuel filter is replaced every 250 hours. The air cleaner
element is inspected every 250 hours and replaced when the restriction
indicator signals.
Valve lash inspection and adjustment at 0.20 mm (0.008 in) for both
intake and exhaust are performed every 500 hours (or 1,000 hours with
optional hydraulic lifters). Coolant replacement is required every 1,000
hours or 24 months. Zinc anodes in the heat exchanger require inspection
every 200 hours and replacement when 50 percent consumed. The timing
belt is not present; the camshaft is gear-driven.
Cylinder Head Bolts, Stage 1: 25 Nm (18 lb-ft)
Cylinder Head Bolts, Stage 2: 60 Nm (44 lb-ft)
Connecting Rod Cap Bolts: 39 Nm (29 lb-ft)
Main Bearing Cap Bolts: 78 Nm (58 lb-ft)
Flywheel Bolts: 72 Nm (53 lb-ft)
Camshaft Bearing Cap Bolts: 20 Nm (15 lb-ft)
Rocker Arm Shaft Bolts: 22 Nm (16 lb-ft)
Intake Manifold Nuts: 20 Nm (15 lb-ft)
Exhaust Manifold Nuts: 25 Nm (18 lb-ft)
Injector Clamp Bolts: 25 Nm (18 lb-ft)
Glow Plugs: 15 Nm (11 lb-ft)
Oil Pan Bolts: 12 Nm (9 lb-ft)
Water Pump Bolts: 12 Nm (9 lb-ft)
Crankshaft Pulley Bolt: 120 Nm (89 lb-ft)
Starter Motor Bolts: 45 Nm (33 lb-ft)
Alternator Mounting Bolts: 25 Nm (18 lb-ft)
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft)
The Yanmar 4JH80 engine is utilized across multiple marine platforms.
Sailboats: Auxiliary propulsion for 40-50 foot heavy displacement
sailboats including Tartan, J/Boats, and Swan models.
Catamarans: Twin-engine installations for 38-45 foot catamarans
providing maneuverability and redundancy.
Motor Yachts: Primary propulsion for downeast boats, lobster yachts, and
pilothouse cruisers.
Workboats: Light commercial vessels including pilot boats and harbor
utility craft.
Lifeboats: Certified SOLAS lifeboat configuration for free-fall and
davit-launched systems.
Small Fishing Vessels: Primary propulsion for coastal fishing craft.
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