Yanmar 4JH2 DTE Specifications
| Engine Model: Yanmar 4JH2 DTE |
| Engine Type: 4-stroke inline 4-cylinder turbocharged water-cooled diesel |
| Total Displacement: 110.9 cu.in (1.82 L) |
| Rated Engine Power: 88 Hp (64.7 kW) at 3600 rpm |
| Fuel System Type: Indirect injection |
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The Yanmar 4JH2-DTE is a turbocharged and
intercooled marine diesel engine from the renowned JH2 series. Produced
from approximately 1988, this four-cylinder powerplant was engineered
for mid-sized sailboats and motor cruisers, offering a high
power-to-weight ratio that established it as a trusted choice in
demanding maritime applications.
The engine features an indirect injection combustion system with a swirl
chamber, delivering smooth operation and reliable cold starting. Its
compact dimensions, combined with forced lubrication, fresh water
cooling with a heat exchanger, and a comprehensive electrical system,
make the 4JH2-DTE a durable and efficient propulsion unit for vessels
requiring dependable auxiliary or primary power.
Engine Type: Vertical, 4-cycle, turbocharged water-cooled diesel.
Number of Cylinders: 4, inline.
Displacement: 1.817 L (110.9 cu.in).
Bore: 82.0 mm (3.23 in).
Stroke: 86.0 mm (3.39 in).
Combustion System: Indirect injection (swirl chamber).
Aspiration: Turbocharged with intercooler.
Maximum Output (Crankshaft): 88 hp (64.7 kW) at 3600 rpm.
Continuous Rating: 75 hp (55.2 kW) at 3500 rpm.
Maximum Torque: 201 Nm (148 lb-ft) at 2200 rpm.
Cruising RPM Range: 2900-3100 rpm.
Direction of Rotation: Counter-clockwise (viewed from flywheel/stern).
Cooling System: Fresh water cooling with heat exchanger (indirect).
Starting System: 12V electric starter (1.4 kW or 1.8 kW).
Alternator: 12V, 55A or 80A.
Dry Weight (excluding gearbox): 234-246 kg (516-542 lb).
The cylinder block is manufactured from high-grade cast iron, providing
the rigidity and vibration damping necessary for continuous marine duty
cycles. The design incorporates four cylinders arranged in-line with a
firing interval optimized for smooth power delivery. The block features
pressed-in or cast-in cylinder liners that can be rebored or replaced
during major overhauls.
Five main bearings support the crankshaft to ensure stability under full
load. The lower crankcase is sealed by a stamped steel oil pan, which
also serves as the oil reservoir. The block is fitted with mounting feet
for secure installation on engine beds and includes a gear housing at
the front for driving auxiliary components such as the camshaft and
injection pump.
The cylinder head is cast from high-grade iron and follows a cross-flow
design. The overhead valve arrangement is actuated by a camshaft located
within the cylinder block, driven by gears from the crankshaft. Pushrods
and rocker arms transfer motion to the valves, which are arranged with
two valves per cylinder.
Valve Arrangement: Overhead valve (OHV), 2 valves per cylinder (8
total).
Valve Train: Camshaft-in-block with pushrods and rocker arms.
Valve Clearance (Cold, Intake and Exhaust): 0.20 mm (0.008 in).
Combustion Chamber: Swirl chamber type (indirect injection).
The cylinder head incorporates the swirl chambers, which create high air
turbulence to promote complete fuel mixing and combustion. This design
results in quieter operation and lower peak cylinder pressures compared
to direct injection systems. Glow plugs are fitted into each swirl
chamber to aid cold starting.
The fuel system utilizes an indirect injection configuration with a
mechanical inline injection pump. The pump is driven by the engine’s
timing gears and delivers fuel to injection nozzles at precisely timed
intervals.
System Type: Indirect injection (swirl chamber).
Injection Pump Type: Mechanical inline plunger pump.
Fuel Injection Pressure: 200-210 kg/cm2 (2844-2986 psi / 19.6-20.6 MPa).
Governor Type: Mechanical, integrated with the injection pump for speed
control.
Fuel Filter: Replaceable cartridge type with water separator.
Cold Start Aid: Glow plugs in each swirl chamber.
The injection timing is adjusted via a shim adjustment or timing device.
The mechanical governor maintains engine speed under varying loads,
which is essential for marine propulsion where propeller load changes
with vessel speed.
The lubrication system is a forced-feed design utilizing a trochoid-type
pump to circulate oil under pressure to all critical moving parts. An
oil cooler, cooled by the freshwater coolant system, maintains stable
oil temperatures during sustained high-power operation.
Lubrication Type: Forced lubrication with trochoid pump and oil cooler.
Total Oil Capacity (with filter): 6.5 L (6.9 qt).
Recommended Oil Grade: SAE 15W-40 or 20W-50 meeting API CF-4 or higher
specifications.
Oil Pump Type: Trochoid (internal gear) pump.
Oil Filter: Full-flow spin-on cartridge type.
The oil sump is mounted below the crankcase and incorporates a drain
plug. The system includes an oil pressure relief valve to limit maximum
pressure. Regular oil changes are critical due to the soot loading
inherent in indirect injection diesel combustion.
The cooling system is an indirect, fresh water (coolant) circuit with a
heat exchanger for raw seawater cooling. This closed-loop system
protects the engine internals from corrosion and scale buildup. A
belt-driven fresh water pump circulates coolant through the cylinder
block and head before passing through a heat exchanger, where raw
seawater absorbs the heat.
Cooling Type: Fresh water cooling with heat exchanger (indirect).
Coolant Capacity (engine and heat exchanger): 7.5 L (7.9 qt).
Fresh Water Pump: Belt-driven centrifugal type.
Seawater Pump: Rubber impeller-type flexible vane pump.
Thermostat Opening Temperature: 71-82°C (160-180°F).
Heat Exchanger: Shell and tube type with zinc anodes for corrosion
protection.
Raw seawater is drawn through a strainer, circulated through the heat
exchanger and exhaust elbow, and discharged overboard. The fresh water
cooling loop maintains the engine at consistent operating temperatures
regardless of seawater conditions.
Turbocharger and Intercooler: The engine is equipped with an IHI RHB52HW
turbocharger, which compresses intake air to increase volumetric
efficiency. Compressed air then passes through a seawater-cooled
intercooler, reducing intake air temperature to increase density and
combustion efficiency. The turbocharger center housing is cooled by
engine coolant.
Exhaust System: A water-cooled mixing elbow injects raw seawater into
the exhaust stream, cooling the exhaust gases and reducing noise. The
exhaust pipe diameter is specified for backpressure management.
Electrical System: The 12V system includes an electric starter motor
(1.4 kW or 1.8 kW) and an alternator (55A or 80A) for battery charging.
The instrument panel includes gauges for tachometer, coolant
temperature, oil pressure, and battery voltage, along with audible
alarms for critical parameters.
Marine Gear: The engine is compatible with KBW20, KBW21, and KM4A series
marine gears. The KBW models feature multiple friction disc clutches for
forward and reverse operation. Reduction ratios available include 2.17,
2.62, 3.28, and others, depending on the specific gearbox model.
Overall Length (engine only): 710 mm (28.0 in).
Overall Length (with gearbox): 906 mm (35.7 in).
Overall Width: 440-561 mm (17.3-22.1 in).
Overall Height: 535-635 mm (21.1-25.0 in).
Dry Weight (without gearbox): 234 kg (516 lb).
Dry Weight (with gearbox): 246 kg (542 lb).
Oil Change Interval: 100-200 hours or annually, API CF-4 or higher grade
oil.
Oil Filter Replacement: Every oil change.
Fuel Filter Replacement: 200-400 hours or annually.
Coolant Replacement: 2 years, using approved antifreeze with corrosion
inhibitors.
Seawater Pump Impeller Inspection: 100 hours.
Seawater Pump Impeller Replacement: 200 hours or annually.
Zinc Anode Inspection: 100 hours; replacement when 50% consumed.
Valve Clearance Inspection: 200 hours; adjust to 0.20 mm (0.008 in)
cold.
Fuel Injection Pressure Nozzle Inspection: 500 hours.
Glow Plug Check: Annually before heating season.
Timing Gear Inspection: 1000 hours or if unusual noise develops.
Turbocharger Inspection: 500 hours for bearing play and seal integrity.
Thermostat Check: Annually; open at specified temperature.
Cylinder Head Nuts (Stage 1): 30 Nm (22 lb-ft).
Cylinder Head Nuts (Stage 2): 60 Nm (44 lb-ft).
Cylinder Head Nuts (Stage 3): 90 Nm (66 lb-ft).
Connecting Rod Cap Nuts: 55 Nm (41 lb-ft).
Main Bearing Cap Bolts: 85 Nm (63 lb-ft).
Flywheel Bolts: 50 Nm (37 lb-ft).
Injection Pump Mounting Nuts: 25 Nm (18 lb-ft).
Injection Nozzle Holder Nuts: 65 Nm (48 lb-ft).
Rocker Arm Bracket Nuts: 25 Nm (18 lb-ft).
Intake Manifold Nuts: 20 Nm (15 lb-ft).
Exhaust Manifold Nuts: 30 Nm (22 lb-ft).
Starter Motor Mounting Bolts: 35 Nm (26 lb-ft).
Alternator Mounting Bolts: 25 Nm (18 lb-ft).
Oil Pan Bolts: 15 Nm (11 lb-ft).
Fresh Water Pump Bolts: 20 Nm (15 lb-ft).
Seawater Pump Bolts: 20 Nm (15 lb-ft).
The Yanmar 4JH2-DTE was produced as a marine propulsion engine for
recreational and light commercial vessels.
Mid-Sized Sailboats: Primary auxiliary power for cruising yachts between
35-45 ft (10.7-13.7 m) requiring reliable diesel propulsion and battery
charging.
Motor Cruisers: Power for displacement and semi-displacement motor
yachts up to 30 ft (9 m) where the 88 hp output provides economical
cruising speeds.
Small Workboats: Propulsion for harbor launches, pilot boats, and light
utility vessels requiring compact, high-power-density diesel engines.
Fishing Vessels: Auxiliary or primary power for small commercial fishing
boats up to 12 m.
Repower Applications: Replacement engine for older sailboats and
powerboats originally fitted with other JH series or competitive models.
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