Mitsubishi 4DR6 Specifications
| Engine Model: Mitsubishi 4DR6 |
| Engine Type: 4-cycle inline 4-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 162.3 cu.in (2.66 L) |
| Rated Engine Power: 93 Hp (69 kW) at 3500 rpm |
| Fuel System Type: Direct injection |
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The Mitsubishi 4DR6 is a 2.7-liter, 4-cylinder,
direct-injection turbocharged diesel engine from the DR series.
Developed as a more efficient successor to the 4DR5 engine, it was
designed primarily to meet stricter emission standards while improving
fuel efficiency and cold-start performance. Produced throughout the late
1980s and early 1990s, the 4DR6 is most famously recognized as the
powerplant for the Mitsubishi Jeep J53 series and also served in
light-duty Canter trucks, industrial forklifts, and stationary generator
applications. The engine combines a direct injection combustion system
with a Mitsubishi TD04 turbocharger operating at a reduced 17.5:1
compression ratio.
The Mitsubishi 4DR6 represents an evolution of the DR diesel
architecture, transitioning from indirect injection in the 4DR5 to
direct injection in this successor. This change enables improved thermal
efficiency, lower fuel consumption, and reduced emissions. The inline
4-cylinder configuration provides a compact powerplant suitable for the
narrow engine bay of the Mitsubishi Jeep. The overhead valve (OHV)
valvetrain with eight valves incorporates a gear-driven camshaft,
eliminating timing belt or chain replacement requirements.
The direct injection combustion system, combining a lower compression
ratio with turbocharging, reduces peak cylinder pressures at start-up
for improved cold cranking. The mechanical fuel injection system
operates without electronic controls, facilitating field repairs. The
Mitsubishi TD04 turbocharger provides increased air density across the
operating range, with peak torque delivered at 2,000 rpm.
Engine Type: Inline 4-cylinder, 4-cycle, water-cooled, turbocharged
diesel
Family: Mitsubishi DR Series
Displacement: 2,659 cc (162.3 cu.in)
Bore x Stroke: 92.0 mm x 100.0 mm (3.62 in x 3.94 in)
Compression Ratio: 17.5:1
Firing Order: 1-3-4-2
Aspiration: Turbocharged with Mitsubishi TD04 turbocharger
Maximum Power: 69 kW (93 hp) @ 3,500 rpm
Maximum Torque: 206 Nm (152 lb-ft) @ 2,000 rpm
Idle Speed: 650-850 rpm, depending on governor setting and application
Valvetrain: OHV, 8 valves (2 valves per cylinder). Mechanical pushrods
and rocker arms. Gear-driven camshaft. Direct injection combustion
system.
The cylinder block is constructed from cast iron with a deep-skirt
design, providing structural rigidity for sustained diesel operation.
The block utilizes a parent-bore design with cylinder bores machined
directly into the cast iron casting. The cylinder bores are
induction-hardened to resist wear under extended service intervals.
Five main bearings support the crankshaft. The water jacket surrounds
each cylinder with cast-in coolant passages optimized for uniform
thermal distribution. The camshaft is located within the cylinder block
on the right-hand side, driven by a gear train from the crankshaft. The
engine mounting points are positioned on the sides and front of the
block.
The cylinder head is manufactured from cast iron, selected for thermal
stability and resistance to distortion under turbocharged diesel
combustion pressures. It employs an OHV configuration with the camshaft
located within the cylinder block. The eight valves are arranged with
two valves per cylinder in a vertical orientation. Valve actuation is
achieved via mechanical pushrods and rocker arms, with screw-and-locknut
adjusters for valve lash setting.
The combustion system utilizes direct injection with a re-entrant bowl
machined into the piston crown. The cylinder head incorporates separate
intake and exhaust ports on opposite sides. The exhaust manifold is
designed to mount the Mitsubishi TD04 turbocharger. Valve seats are
induction-hardened, with valve guides manufactured from cast iron.
The engine is equipped with a mechanical direct injection fuel system.
An in-line injection pump, manufactured by Bosch or Zexel, is mounted to
the side of the cylinder block, driven by a gear from the camshaft. The
injection pump incorporates a mechanical governor, providing speed
control and load response. Injection timing is adjustable via shims
between the pump mounting flange and the block.
Each cylinder receives fuel from a nozzle-type injector, with injector
opening pressure calibrated to approximately 120-130 bar (1,740-1,885
psi). A fuel supply pump draws fuel through a primary filter and water
separator assembly. Excess fuel returns to the tank via a spill line.
The direct injection system uses lower compression than indirect
injection predecessors, improving cold-start performance.
The lubrication system is a pressurized, wet-sump configuration designed
for industrial duty cycles. A gear-type oil pump, driven by the
crankshaft, draws oil from the sump and circulates it through a
full-flow disposable spin-on filter. An optional oil cooler may be
fitted for high-ambient-temperature applications.
Oil galleries within the block and cylinder head supply pressurized oil
to the main bearings, connecting rod bearings, camshaft bearings, rocker
arm assemblies, and turbocharger bearing housing. The turbocharger
receives oil through a dedicated supply line with a restrictor fitting.
A pressure relief valve maintains system pressure. Total oil capacity is
7.0-8.0 liters (7.4-8.5 qt), depending on oil pan depth and application.
The cooling system is a pressurized, water-cooled design with forced
circulation. A belt-driven centrifugal water pump, mounted to the front
of the cylinder block, circulates coolant through the cylinder block,
cylinder head, turbocharger bearing housing, and radiator.
A wax-type thermostat, beginning to open at 71-76°C (160-169°F),
regulates coolant flow. This lower thermostat opening temperature is
specified for sustained high-load industrial and off-road operation. The
system utilizes a cross-flow radiator with a mechanical or electric
cooling fan depending on the vehicle application.
Glow Plug System: The engine is equipped with glow plugs for cold-start
assistance. One glow plug per cylinder is installed in the cylinder
head, controlled by a glow control unit or manual push-button circuit.
Timing System: The camshaft and injection pump are driven by a gear
train housed at the front of the engine. The crankshaft gear drives an
idler gear, which in turn drives the camshaft gear and injection pump
gear. This gear-driven arrangement eliminates timing belt or chain
replacement requirements.
Turbocharger System: The Mitsubishi TD04 turbocharger features a fixed
geometry design. The turbocharger is mounted to the exhaust manifold,
with boost pressure regulated by a wastegate actuator. Maximum boost
pressure is approximately 0.6-0.8 bar (9-12 psi) at full load.
Governor System: The mechanical governor integrated into the injection
pump includes low-idle and high-speed control functions, calibrated for
the specific vehicle or industrial application.
Emission Control: The engine incorporates a positive crankcase
ventilation (PCV) system. No catalytic converter is present on standard
4DR6 configurations.
Electrical System: The charging system consists of a 12-volt alternator.
The starter motor is sized for diesel cranking requirements.
Dry Weight (Engine Only): 280 kg (617 lb)
Dry Weight (with Flywheel and Bellhousing): 310 kg (683 lb)
Overall Length (from front pulley to flywheel housing): 890 mm (35.0 in)
Overall Width: 590 mm (23.2 in)
Overall Height: 870 mm (34.3 in)
Bore Pitch: 106 mm (4.17 in)
Engine Oil Capacity: 7.0-8.0 liters (7.4-8.5 qt), depending on oil pan
configuration
Engine Oil Specification: SAE 15W-40, 10W-30 meeting API CD, CE, CF, or
higher
Engine Oil Pressure (at idle): Minimum 0.8 bar (12 psi)
Engine Oil Pressure (at rated speed): 3.0-4.5 bar (44-65 psi)
Coolant Capacity: Variable by application; engine only 6.0 liters (6.3
qt)
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors
Valve Clearance (Cold): Intake: 0.25 mm (0.010 in). Exhaust: 0.25 mm
(0.010 in)
Valve Clearance Inspection Interval: Every 500 operating hours
Fuel Injection Timing: 10°-12° BTDC at injection pump installation
Injector Opening Pressure: 120-130 bar (1,740-1,885 psi)
Oil Change Interval: 250-500 hours, depending on duty cycle and oil
quality
Fuel Filter Replacement Interval: 250 operating hours
Idle Speed: 650-850 rpm, depending on governor setting
High Idle No-Load Speed: 2,800-3,000 rpm, depending on governor
calibration
Compression Pressure: Standard: 26-30 bar (377-435 psi) at cranking
speed
Cylinder Head Bolts, Stage 1: 50 Nm (37 lb-ft)
Cylinder Head Bolts, Stage 2: 90 Nm (66 lb-ft)
Cylinder Head Bolts, Stage 3: 118-127 Nm (87-94 lb-ft)
Main Bearing Cap Bolts: 100-110 Nm (74-81 lb-ft)
Connecting Rod Cap Bolts: 49-54 Nm (36-40 lb-ft)
Camshaft Bearing Cap Bolts: 20-25 Nm (15-18 lb-ft)
Flywheel Bolts: 85-95 Nm (63-70 lb-ft)
Crankshaft Pulley Bolt: 200-250 Nm (148-184 lb-ft)
Intake Manifold Nuts: 20-25 Nm (15-18 lb-ft)
Exhaust Manifold Nuts: 30-35 Nm (22-26 lb-ft)
Injector Hold-Down Clamp Bolts: 20-25 Nm (15-18 lb-ft)
Glow Plugs: 15-20 Nm (11-15 lb-ft)
Rocker Arm Shaft Bracket Bolts: 25-30 Nm (18-22 lb-ft)
Valve Cover Bolts: 8-10 Nm (6-7 lb-ft)
Oil Pan Bolts: 15-20 Nm (11-15 lb-ft)
Oil Pump Mounting Bolts: 25-30 Nm (18-22 lb-ft)
Water Pump Mounting Bolts: 20-25 Nm (15-18 lb-ft)
Turbocharger Mounting Nuts: 35-40 Nm (26-30 lb-ft)
Injection Pump Mounting Nuts: 30-35 Nm (22-26 lb-ft)
Engine Mount (Bracket to Block): 50-60 Nm (37-44 lb-ft)
The Mitsubishi 4DR6 engine was utilized across a range of automotive,
industrial, and power generation applications throughout its production
lifecycle.
Mitsubishi Jeep J53 Series: 1986-1994, the 4DR6 served as the primary
diesel powerplant for the J53 and P-J53 canvas top versions of the
Mitsubishi Jeep, replacing the 4DR5 in this iconic off-road vehicle
produced under license from Willys.
Mitsubishi Jeep Wagon: Limited wagon body configurations of the J53
series received the 4DR6 engine for passenger and utility applications.
Mitsubishi Canter (Light-Duty Truck): Selected light-duty variants of
the Mitsubishi Canter truck received the 4DR6 engine, particularly in
Asian and Pacific markets, for urban delivery applications requiring a
turbocharged diesel powerplant.
Industrial Forklift Trucks: Heavy-duty forklift trucks in the 4-6 tonne
capacity class utilized the 4DR6 engine for material handling
applications requiring sustained low-speed torque.
Stationary Generators: The 4DR6 was configured as a stationary generator
powerplant for prime and standby power applications in remote locations.
Agricultural Equipment: Certain agricultural machinery including
tractors and self-propelled harvesters in Asian markets received the
4DR6 engine as a powerplant option.
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