Mitsubishi 4DR5 Specifications
| Engine Model: Mitsubishi 4DR5 |
| Engine Type: 4-cycle inline 4-cylinder full-pressure lubrication liquid-cooled diesel |
| Total Displacement: 162.3 cu.in (2.66 L) |
| Rated Engine Power: 80-100 Hp (59-74 kW) at 4200 rpm |
| Fuel System Type: Indirect fuel injection |
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The Mitsubishi 4DR5 is a 2.7-liter inline-four,
four-stroke, water-cooled diesel engine produced by Mitsubishi Motors
for its range of light trucks, SUVs, and utility vehicles. This engine
was part of the 4D5 family and gained a strong reputation for its
durability, mechanical simplicity, and ability to perform reliably under
harsh operating conditions.
It powered vehicles such as the Mitsubishi J53
and J54 Jeep, the early Pajero models, and various commercial trucks.
The 4DR5 was developed as an improvement over the earlier 4DR1 and 4DR3
units, offering higher output, smoother operation, and improved fuel
efficiency.
The engine was manufactured in both naturally aspirated (NA) and
turbocharged configurations. The NA version was known for its simplicity
and ruggedness, making it popular in off-road and military applications.
The turbocharged version provided increased power and torque for heavier
loads and highway performance.
Both variants employed indirect injection and
featured a robust cast-iron block and head construction. Known for its
long service life and ability to tolerate poor fuel quality, the 4DR5
remains highly regarded among enthusiasts and professionals who value
reliability over sophistication.
The Mitsubishi 4DR5 is a four-cylinder inline engine with a total
displacement of 2,659 cc (2.7 liters, 162.3 cubic inches). The cylinder
bore measures 92.0 mm (3.62 inches), and the piston stroke is 100.0 mm
(3.94 inches), resulting in an undersquare configuration favoring torque
over high-end power. The compression ratio for the naturally aspirated
version is approximately 21.0:1, while the turbocharged variant operates
at around 20.0:1 to accommodate increased cylinder pressures.
The engine block and cylinder head are both made from cast iron,
ensuring excellent wear resistance and thermal stability. The crankshaft
is forged steel, supported by five main bearings. Pistons are cast
aluminum alloy with reinforced ring lands and a combustion chamber
recess. Each piston carries three rings - two compression and one oil
control ring - providing effective sealing under high compression
conditions. Connecting rods are forged steel, designed to withstand the
high loads typical of diesel operation.
The camshaft is located in the cylinder head and operates two valves per
cylinder (one intake, one exhaust) via rocker arms and pushrods. Valve
clearance is adjustable through screw-and-locknut mechanisms, allowing
precise adjustment during servicing. The firing order is 1-3-4-2, and
the engine rotates clockwise viewed from the front.
Maximum power output for the naturally
aspirated version is approximately 80 Hp (59 kW, 79 bhp) at 4,200
revolutions per minute, while the turbocharged version develops about
100 Hp (74 kW, 99 bhp) at the same speed. Peak torque figures are 172 Nm
(127 lb-ft) at 2,200 rpm for the NA model and approximately 216 Nm (159
lb-ft) for the turbocharged variant.
Idle speed is typically set at 750 ± 50 rpm, and the governed speed is
limited to around 4,300 rpm. The redline is around 4,500 rpm, which is
high for a diesel of this era but achievable due to the engine’s
balanced reciprocating mass and strong bottom end.
The 4DR5 employs an indirect fuel injection system utilizing a
pre-combustion chamber design to ensure smooth combustion and reduced
diesel knock. Fuel is supplied by a mechanical in-line fuel injection
pump manufactured by Mitsubishi or licensed Bosch designs, driven
directly by the engine through timing gears. Fuel delivery is
synchronized with the camshaft to inject precisely metered amounts of
fuel into each cylinder in sequence. Injector nozzles are pintle-type
with opening pressures around 17.5 Mpa (2,540 psi).
Fuel is drawn from the tank through a primary filter and hand primer
pump, then delivered to the injection pump under low pressure. A
secondary fine filter ensures clean fuel delivery to the injectors. The
turbocharged variant uses slightly larger injector nozzles and a
recalibrated injection pump to deliver higher fuel quantities in
proportion to the increased air charge. The fuel return line routes
excess diesel back to the tank to maintain constant pressure and prevent
vapor formation. Recommended fuel is standard automotive diesel with
cetane rating above 50.
The lubrication system is a full-pressure wet-sump type employing a
trochoid gear oil pump driven by the crankshaft. Oil is drawn through a
strainer and delivered to the main oil gallery, feeding crankshaft
bearings, connecting rod journals, camshaft bearings, and rocker arms.
The system also supplies oil to the turbocharger on forced-induction
models via a dedicated feed line with return to the sump. A full-flow
replaceable cartridge-type oil filter is mounted on the side of the
engine block. Oil pressure at idle is approximately 100 kPa (15 psi),
and at 3,000 rpm around 400 kPa (58 psi).
Oil capacity with filter replacement is approximately 7.0 liters (7.4 US
quarts, 6.2 Imperial quarts). Recommended engine oil grades are SAE
10W-30 or 15W-40 meeting API CF or higher specifications, depending on
ambient temperature. Under severe operating conditions, such as
high-load or dusty environments, oil and filter changes should occur
every 5,000 km (3,000 miles). Normal service intervals are every 10,000
km (6,000 miles). The positive crankcase ventilation (PCV) system
ensures minimal oil vapor emissions and maintains crankcase pressure
balance.
The cooling system is a water-cooled, pressurized type with belt-driven
centrifugal water pump. Coolant circulates through the cylinder block,
head, radiator, and heater core. The thermostat begins to open at 80°C
(176°F) and is fully open by 95°C (203°F). Cooling system pressure is
maintained at about 88 kPa (13 psi) using a spring-loaded radiator cap.
A mechanical fan mounted on the water pump pulley provides airflow,
while some later turbocharged variants use a viscous clutch-type fan for
better control. Total coolant capacity is approximately 9.0 liters (9.5
US quarts, 7.9 Imperial quarts).
Recommended coolant mixture is 50% ethylene glycol antifreeze and 50%
distilled water, protecting against freezing down to –35°C (–31°F). The
coolant should be replaced every 40,000 km (25,000 miles) or two years.
The system includes a temperature sender for the dashboard gauge and an
additional sensor for glow plug control in cold start operation.
| Intake and Exhaust Systems |
The naturally aspirated version employs a simple intake manifold drawing
air through an oil-bath or dry-type air cleaner, depending on
application. The turbocharged 4DR5 uses a small Mitsubishi TD04
turbocharger operating at approximately 0.5 bar (7 psi) of boost
pressure. The intake manifold is designed to distribute the charge
evenly among the cylinders. There is no intercooler in standard
configuration, though some later retrofit versions employed air-to-air
cooling for improved performance.
The exhaust manifold on turbo models is cast iron, designed to withstand
high thermal loads, and routes gases directly to the turbocharger
turbine housing. The naturally aspirated version has a simpler manifold
optimized for low restriction. The exhaust system employs a
large-diameter pipe and muffler to minimize backpressure while
maintaining acceptable noise levels.
The electrical system operates on 12 volts DC. The engine is equipped
with glow plugs for cold starting, each with a rated voltage of 11
volts. The glow plug relay and control timer preheat the combustion
chambers for 5 to 10 seconds depending on temperature. The alternator
output ranges from 35 to 50 amperes, depending on vehicle configuration.
The starter motor is a robust 2.0-kilowatt reduction-gear type to ensure
reliable cranking even in cold conditions.
Spark plugs are not used, as combustion is initiated by compression
ignition. The wiring harness includes temperature sensors for coolant
and oil, alternator charge indicator, and starter solenoid connections.
Proper battery maintenance is essential; typical specification is 12
volts, 70 ampere-hours.
Overall engine dimensions are approximately 780 mm (30.7 inches) in
length, 670 mm (26.4 inches) in width, and 780 mm (30.7 inches) in
height. Dry weight is about 230 kg (507 lbs) for the naturally aspirated
version and approximately 240 kg (529 lbs) for the turbocharged variant.
The engine mounts use three points - two side mounts and one rear - to
isolate vibration and noise transmission to the chassis.
Recommended intervals include: engine oil and filter every 10,000 km
(6,000 miles), air cleaner service every 20,000 km (12,000 miles), and
fuel filter replacement every 20,000 km (12,000 miles). Valve clearance
should be inspected every 20,000 km (12,000 miles) and adjusted when the
engine is cold. Clearance settings: intake valve 0.25 mm (0.010 inch),
exhaust valve 0.35 mm (0.014 inch). Glow plugs should be checked for
resistance periodically; normal reading is 0.5 to 1.0 ohm.
Compression pressure for a healthy engine should measure around 2,940
kPa (426 psi) at 200 rpm, with a minimum allowable value of 2,450 kPa
(356 psi). The difference between cylinders should not exceed 300 kPa
(44 psi). Engine idle speed is adjusted via the governor screw, and
timing is set mechanically by aligning pump and camshaft timing marks.
Cylinder head bolts: tighten in three stages - first 39 Nm (29 lb-ft),
second 78 Nm (58 lb-ft), final 108 Nm (80 lb-ft).
Main bearing cap bolts: 93 Nm (69 lb-ft).
Connecting rod bolts: 54 Nm (40 lb-ft).
Flywheel bolts: 88 Nm (65 lb-ft) plus 60 degrees.
Crankshaft pulley bolt: 167 Nm (123 lb-ft).
Rocker cover bolts: 9 Nm (7 lb-ft).
Intake manifold bolts: 25 Nm (18 lb-ft).
Exhaust manifold nuts: 35 Nm (26 lb-ft).
Oil drain plug: 40 Nm (30 lb-ft).
Glow plugs: 15 Nm (11 lb-ft).
The Mitsubishi 4DR5 engine was installed in a wide range of vehicles
between the 1970s and 1990s.
Key applications include:
– Mitsubishi J53/J54 Jeep series (civilian and military variants).
– Mitsubishi Pajero (early models before 4D55 introduction).
– Mitsubishi Delica trucks and vans (domestic market).
– Mitsubishi Canter light trucks (early versions).
– Industrial and stationary applications such as generators and
agricultural machinery.
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