Mitsubishi 4D32 Specifications
| Engine Model: Mitsubishi 4D32 |
| Engine Type: 4-cycle inline 4-cylinder liquid-cooled diesel |
| Total Displacement: 217 cu.in (3.57 L) |
| Rated Engine Power: 108 Hp (81 kW) at 3500 rpm |
| Fuel System Type: Direct injection |
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The Mitsubishi 4D32 is a 3.6-liter, naturally
aspirated, inline-four diesel engine produced from the late 1980s
through the mid-1990s. As a displacement upgrade within the 4D3x engine
series, this power unit was engineered for light-duty trucks,
generators, and marine applications where increased low-end torque and
reliability were prioritized over turbocharged power. The Mitsubishi
4D32 shares the overhead valve (OHV) architecture and direct injection
combustion system of the 4D31 series, with a larger bore of 104 mm
increasing displacement to 3.6 liters.
The engine uses a mechanical inline injection pump, a gear-driven
camshaft, and a robust cast iron construction that has made it a
favorite for long-term commercial service. The 4D32 was widely installed
in the Mitsubishi Fuso Canter (FE series) light-duty trucks, as well as
in generator sets and small marine vessels where naturally aspirated
simplicity and fuel efficiency were required. A higher compression ratio
of 18.0:1, compared to turbocharged variants, provides excellent
cold-start performance and thermal efficiency.
The Mitsubishi 4D32 is a four-stroke, water-cooled, inline-four diesel
engine with a total displacement of 3,567 cc (3.6 L / 217 cu.in). The
bore and stroke dimensions are 104 mm (4.09 in) and 105 mm (4.13 in),
respectively, creating an undersquare configuration that emphasizes
low-end torque production. The valvetrain employs an overhead valve
(OHV) design with two valves per cylinder - one intake and one exhaust -
for a total of eight valves.
The camshaft is positioned within the cylinder block and actuates the
valves through pushrods and rocker arms. The combustion system uses
direct injection with a multi-hole injector nozzle. Induction is
naturally aspirated, drawing air through a dry-type air filter and
intake manifold without forced induction assistance. The compression
ratio is set at 18.0:1, a value selected to provide reliable cold-start
performance and high thermal efficiency in the naturally aspirated
configuration. Standard compression pressure is 2.75 MPa (398 psi), with
a minimum service limit of 1.96 MPa (284 psi).
Injection timing is specified between 13 and 16 degrees before top dead
center (BTDC), with the exact value determined by the engine data plate
for each serial number. Maximum power is 81 kW (110 PS / 108 hp) at
3,500 rpm. Peak torque is 255 Nm (188 lb-ft) at 1,800 to 2,000 rpm. The
engine speed limiter is set at 3,800 rpm. The firing order is 1-3-4-2,
the standard arrangement for inline-four engines.
The cylinder block is constructed from cast iron, a material selected
for its exceptional rigidity, wear resistance, and ability to withstand
the high compressive loads of diesel combustion. The inline-four
configuration incorporates five main bearings supporting a forged steel
or nodular iron crankshaft. The crankshaft is dynamically balanced and
fully counterweighted to minimize vibration across the operating range.
The connecting rods are forged steel.
Cylinder bores are machined directly into the cast iron block. Some
versions incorporate replaceable dry-type cylinder liners, while others
use parent bore construction depending on the production year. A plateau
honed finish optimizes oil retention and piston ring sealing. The water
jacket surrounds the cylinders for effective heat transfer, with coolant
flow directed upward toward the cylinder head. The block incorporates a
deep-skirt design to maximize structural stiffness. The timing gear
housing is integrated into the front of the block, housing the gear
train that drives the camshaft and injection pump.
The cylinder head is manufactured from cast iron, matching the thermal
expansion characteristics of the block to ensure consistent head gasket
sealing. The overhead valve (OHV) arrangement positions the camshaft
within the block, with valve actuation provided by pushrods and rocker
arms. The rocker arms pivot on a rocker shaft mounted to the cylinder
head and are adjustable to set valve clearance.
Valves are arranged in-line along the cylinder head axis, with each
cylinder served by one intake valve and one exhaust valve. The direct
injection combustion chamber is formed primarily within the piston
crown, with the cylinder head providing a shallow recess to accommodate
the injector nozzle. Valve seat inserts are pressed into the cylinder
head and machined to precise angles. The valve springs are of the
single-coil type. The cylinder head gasket is a composite or multi-layer
steel design, providing reliable sealing between the cast iron head and
cast iron block.
The fuel system is a mechanical direct injection system utilizing an
inline injection pump mounted to the cylinder block and driven by the
timing gear train. Each cylinder has its own pump element (plunger and
barrel) delivering high-pressure fuel through steel lines to the
injection nozzles. A mechanical all-speed governor integrated into the
injection pump maintains engine speed under varying loads, automatically
adjusting fuel delivery to hold the set speed.
The injection nozzles are of the multi-hole type (usually 4 holes)
designed for direct injection into the piston bowl. The nozzle opening
pressure is calibrated to the engine specifications. A feed pump,
integral to the injection pump, draws fuel from the vehicle-mounted tank
through a water-separating primary filter and a secondary fine filter. A
manual primer lever allows bleeding of air from the system after filter
replacement. The injection timing is mechanically adjustable by shimming
the pump mounting flange or rotating the pump housing.
The lubrication system is a full-pressure, full-flow circuit utilizing a
gear-type oil pump mounted within the timing gear case. The pump draws
engine oil from a large-capacity steel sump through a strainer screen
before directing it through a spin-on full-flow oil filter. An oil
cooler is integrated into the lubrication circuit on some
configurations.
The main oil gallery distributes pressurized oil to the crankshaft main
bearings, connecting rod bearings, camshaft bearings, rocker arm
assemblies, and the timing gear train. The total engine oil capacity
ranges from 7.5 L (7.9 qt) to 8.5 L (9.0 qt) depending on the oil pan
depth. Recommended oil viscosity is SAE 15W-40 or 10W-30 with diesel
ratings of API CD, CE, or CF-4.
The cooling system is a thermostatically controlled water circulation
circuit. A belt-driven centrifugal water pump, mounted to the front of
the cylinder block, circulates a mixture of water and ethylene glycol
antifreeze through the cylinder block, cylinder head, and the radiator.
Coolant flow is directed first to the cylinder block for even cooling
before ascending into the cylinder head.
The thermostat is a wax-pellet type positioned on the coolant outlet of
the cylinder head, maintaining engine temperature within the range of
80°C to 90°C (176°F to 194°F). The radiator is a vertical or cross-flow
construction with sufficient capacity for light-duty truck applications.
An engine-driven fan with viscous clutch provides cooling airflow. An
expansion tank allows for coolant expansion. The total cooling system
capacity varies by equipment configuration but is 10.0 L (10.6 qt) to
12.0 L (12.7 qt).
| Intake and Exhaust Systems |
Intake System: The intake manifold is constructed from cast iron. The
naturally aspirated induction system draws air through a dry-type paper
air filter housed in a metal air cleaner assembly. An intake silencer
reduces induction noise.
Exhaust System: The exhaust manifold is constructed from cast iron. The
exhaust system includes a muffler and, in later versions, a diesel
oxidation catalyst depending on the market.
The electrical system operates on 12 volts for most vehicle applications
and 24 volts for some industrial and marine installations. A high-output
alternator provides charging current. A high-torque starter motor is
mounted to the flywheel housing. Glow plugs are installed in the
cylinder head, with glow duration controlled by a manual switch or
automatic timer based on coolant temperature.
The overall length, measured from the front pulley to the flywheel
housing face, is 850 mm (33.5 in). Width across the cylinder head and
injection pump is 600 mm (23.6 in). Height from the bottom of the oil
sump to the top of the cylinder head cover is 900 mm (35.4 in). The dry
weight of the engine, inclusive of the intake and exhaust manifolds,
injection pump, starter, alternator, and flywheel but without
transmission or fluids, is 265 kg (584 lb).
The engine oil and filter must be replaced at intervals of 5,000 km
(3,107 mi) or 100 operating hours under severe duty, with intervals
extending to 10,000 km (6,214 mi) or 200 hours under normal highway
operation. The oil capacity ranges from 7.5 L (7.9 qt) to 8.5 L (9.0
qt). The fuel filter requires replacement every 10,000 km (6,214 mi) or
200 operating hours.
The air filter primary element requires service when the restriction
indicator shows elevated vacuum levels. Valve clearance adjustment is
required at intervals of 20,000 km (12,427 mi) or 400 operating hours,
with cold clearances of 0.40 mm (0.016 in) for both intake and exhaust
valves.
The cooling system requires periodic flushing and coolant replacement
every 12 months or 500 operating hours. The injection timing should be
checked and adjusted at major overhaul intervals. The glow plugs should
be tested before each cold season and replaced if resistance values
deviate from specification.
Cylinder Head Bolts: 175 Nm (129 lb-ft).
Main Bearing Cap Bolts: 175 Nm (129 lb-ft).
Connecting Rod Bolts: 100 Nm (74 lb-ft).
Rocker Arm Shaft Bracket Bolts: 30 to 35 Nm (22 to 26 lb-ft).
Rocker Arm Adjustment Locknuts: 20 to 25 Nm (15 to 18 lb-ft).
Flywheel Bolts: 120 Nm (89 lb-ft).
Crankshaft Pulley Bolt: 250 to 300 Nm (184 to 221 lb-ft).
Intake Manifold Bolts: 25 to 30 Nm (18 to 22 lb-ft).
Exhaust Manifold Nuts: 30 to 35 Nm (22 to 26 lb-ft).
Injection Pump Mounting Nuts: 25 to 30 Nm (18 to 22 lb-ft).
Injection Nozzle Holders: 70 to 80 Nm (52 to 59 lb-ft).
Oil Pan Bolts: 15 to 20 Nm (11 to 15 lb-ft).
Glow Plugs: 15 to 20 Nm (11 to 15 lb-ft).
The Mitsubishi 4D32 engine was deployed across light-duty trucks,
industrial equipment, and marine applications.
Mitsubishi Fuso Canter (FE Series): The 4D32 served as a naturally
aspirated diesel engine option in the Mitsubishi Fuso Canter light-duty
truck range. This application included gross vehicle weight ratings from
3,500 kg to 7,500 kg (7,700 to 16,500 lb). The engine was paired with
five-speed manual transmissions. Applications included box trucks, stake
trucks, refrigerated vans, and chassis-cab configurations.
Mitsubishi Delica / L300 (Some Markets): In select markets, the 4D32 was
installed in heavy-duty variants of the Mitsubishi Delica van and L300
platform, providing diesel power for commercial passenger transport and
delivery applications.
Generator Drive Power Units: The 4D32 was used as a prime mover or
standby generator engine, providing reliable power at constant 1,500 or
1,800 rpm for 50 Hz or 60 Hz operation. These applications included
open-skid generator sets for industrial and agricultural use.
Marine Propulsion: The 4D32 was offered as a marine auxiliary engine for
small workboats, fishing vessels, and sailboats, equipped with a heat
exchanger cooling system and a marine gearbox adapter.
Industrial Power Units: The 4D32 was sold as a stationary power unit for
pumps, compressors, and agricultural machinery. These applications used
a radiator cooling package matched to the specific installation.
Mitsubishi Heavy Machinery: The 4D32 was used in various
Mitsubishi-branded industrial equipment, including forklifts and small
wheel loaders. The engine remained in production in certain markets
until approximately 1998, when it was gradually replaced by the 4M50 and
later 4P10 series engines.
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