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Mitsubishi 4D33 Specifications
| Engine Model: Mitsubishi 4D33 |
| Engine Type: 4-cycle inline 4-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 257 cu.in (4.21 L) |
| Rated Engine Power: 85-90 Hp (63-66 kW) at 3200 rpm |
| Fuel System Type: Direct fuel injection |
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- Mitsubishi 4D36 Engine Specifications
| General Technical Data |
The Mitsubishi 4D33 is a 4.2-liter inline four-cylinder, water-cooled diesel engine that forms part of the renowned 4D3 family, which also includes the 4D30, 4D31, and 4D34. Developed by Mitsubishi Heavy Industries and introduced in the early 1980s, the 4D33 became one of the most widely used medium-duty diesel engines in the Mitsubishi Canter and other light commercial vehicles.
Known for its robust cast-iron construction,
long service life, and ability to handle continuous heavy loads, the
4D33 exemplifies Mitsubishi’s focus on mechanical simplicity and
reliability. Initially produced as a naturally aspirated engine, later
variants introduced turbocharging to improve output and torque while
maintaining the same displacement and structural design.
The 4D33 was designed primarily for commercial vehicles, buses, and
light-duty trucks operating under demanding conditions. Its
straightforward mechanical fuel injection system and overhead valve
(OHV) design made it easy to service even in remote locations.
With minimal electronic control systems, the
4D33 became especially popular in markets requiring rugged engines
capable of long hours of operation on varied fuel quality. The naturally
aspirated version prioritized reliability and smooth torque delivery,
while the turbocharged version added improved performance and fuel
efficiency for heavier vehicle applications.
The 4D33 engine features four cylinders arranged in-line, operating on
the four-stroke diesel cycle. The bore is 108 mm (4.25 inches) and the
stroke is 115 mm (4.53 inches), producing a total displacement of 4,214
cc (4.21 liters or 257 cubic inches).
The compression ratio for the naturally
aspirated version is approximately 18.5:1, while the turbocharged
variant operates at around 17.5:1. The engine block and cylinder head
are both made of cast iron to ensure rigidity and durability. The
crankshaft runs on five main bearings, contributing to smooth operation
and extended service life.
In its naturally aspirated form, the 4D33 produces approximately 85 to
90 Hp (63 to 66 kW, 84 to 89 bhp) at around 3,200 revolutions per
minute. Maximum torque is about 206 Nm (152 lb-ft) at 2,000 rpm. The
turbocharged version, depending on configuration, delivers between 100
and 120 Hp (74 to 88 kW, 99 to 118 bhp) at 3,200 rpm, and torque output
ranging from 275 to 310 Nm (203 to 229 lb-ft) at approximately 1,800 to
2,000 rpm. The firing order is 1-3-4-2, and engine idle speed is
typically 700 ± 50 rpm. Redline speed is limited to about 3,500 rpm.
The engine employs a direct-injection combustion system using
pre-combustion chambers in early versions, later revised to a more
efficient swirl-chamber design. Pistons are aluminum alloy with steel
inserts to withstand high combustion pressures. Connecting rods are
forged steel, and the camshaft is located within the block, driven by a
gear train. The valve train uses pushrods and rocker arms to actuate two
valves per cylinder, ensuring mechanical simplicity and ease of
adjustment.
| Fuel System |
The Mitsubishi 4D33 uses a mechanically controlled fuel injection system based on a distributor-type or inline injection pump (depending on model year and market). The pump is typically a Bosch or Zexel inline-type with mechanical governor control.
Fuel is drawn from the tank by a mechanical lift pump, passed through a
primary sedimenter and fine fuel filter, and then delivered to the
injection pump. From there, high-pressure fuel is distributed to each
injector through steel lines. Injection pressure is typically around
17–20 Mpa (2,465–2,900 psi).
The injectors are pintle-type, spring-loaded units that atomize fuel
into the combustion chambers. Injection timing is set mechanically and
should be precisely adjusted during service for optimal combustion
efficiency. In turbocharged versions, injection timing and fueling rate
are modified to prevent excessive smoke and combustion temperature.
Fuel return lines route excess fuel from the injectors and pump back to the tank for cooling and circulation. Fuel filter replacement is recommended every 20,000 km (12,000 miles), and injector service every 80,000 km (50,000 miles). Diesel fuel of 50 cetane number or higher is recommended for clean combustion.
| Lubrication System |
The lubrication system is a fully pressurized wet-sump type. An internal gear-type oil pump, driven by the crankshaft gear train, draws oil through a mesh strainer and sends it through a full-flow spin-on filter before distributing it to the main bearings, connecting rods, camshaft, and valve mechanism.
Oil jets located beneath the pistons spray oil to cool the piston
crowns, which is particularly important in turbocharged engines. The
normal oil pressure is approximately 350 kPa (50 psi) at 3,000 rpm and
around 100 kPa (15 psi) at idle.
Total oil capacity with filter is approximately 7.5 liters (7.9 US
quarts, 6.6 Imperial quarts). Recommended oil types are SAE 15W-40 or
10W-30 diesel-grade oils meeting API CF or higher specifications.
Oil change intervals are every 10,000 km (6,000 miles) or 6 months under normal conditions, with more frequent service under severe operation. The crankcase ventilation system employs a breather valve to prevent pressure buildup and oil contamination. A magnetic drain plug is fitted in the oil pan to collect metallic particles.
| Cooling System |
The engine uses a liquid cooling system with a belt-driven centrifugal water pump. Coolant circulates through the cast-iron block and head, assisted by a thermostat that begins to open at 80°C (176°F) and is fully open by 95°C (203°F). Cooling is maintained by a large front-mounted radiator and mechanical fan with viscous coupling in later versions.
Total coolant capacity is approximately 10.5 liters (11.1 US quarts, 9.2
Imperial quarts). The system operates under a pressure of about 88 kPa
(13 psi). Recommended coolant is a 50/50 mix of ethylene glycol and
distilled water, providing freeze protection down to –35°C (–31°F).
For heavy-duty applications, an oil cooler is integrated into the
cooling circuit to maintain oil temperature stability. Turbocharged
engines use a larger radiator and sometimes an auxiliary fan to handle
the additional thermal load. Regular coolant replacement is advised
every 40,000 km (25,000 miles) or two years. Overheating must be
avoided, as thermal stress may cause head gasket failure or valve seat
distortion in high-mileage engines.
| Intake and Exhaust Systems |
The naturally aspirated 4D33 employs a conventional dry air filter and cast-iron intake manifold. Air enters through a large cylindrical air cleaner with replaceable paper element, designed for dusty environments. The turbocharged version uses a Mitsubishi TD04 or equivalent small turbocharger producing boost pressures between 0.5 and 0.8 bar (7–12 psi).
In later models, an air-to-air intercooler is added to reduce intake air
temperature and improve volumetric efficiency. The exhaust manifold is
made of high-temperature cast iron and is designed to channel gases
efficiently toward the turbocharger or exhaust pipe.
Exhaust gas recirculation (EGR) is absent in early models but introduced
in later emissions-compliant variants to reduce nitrogen oxide
formation. The muffler system is optimized for low back pressure and
durability, using double-layer steel construction. The turbocharged
engines benefit from improved torque characteristics, particularly under
load, without sacrificing reliability.
Intake air filter replacement is recommended every 20,000 km (12,000
miles) or more frequently in dusty environments. Turbocharger inspection
should be performed at 100,000 km (62,000 miles), checking for shaft
play and oil leakage.
| Electrical System |
The electrical system includes glow plugs for cold starting, controlled
by a timer relay. Glow plug preheating lasts approximately 5 to 10
seconds depending on temperature. The alternator is rated at
approximately 24 volts and 50–70 amperes for commercial vehicles, with a
24-volt starter motor delivering around 3 kW. Battery configuration
typically uses two 12-volt units connected in series.
The engine control system is purely mechanical on early versions, while
later models include basic electronic control for cold-start advance or
idle-up under accessory load. All wiring harnesses are shielded for
durability, and engine grounding is ensured through multiple points on
the block.
| Dimensions and Weight |
Overall length: 950 mm (37.4 inches).
Width: 680 mm (26.8 inches).
Height: 880 mm (34.6 inches).
Dry weight: approximately 260 kg (573 lbs) for the naturally aspirated
version and about 280 kg (617 lbs) for the turbocharged model.
The engine’s compact yet heavy-duty construction allows easy integration
into medium trucks and buses. The rigid block structure minimizes
vibration, and engine mounts use thick rubber isolators to reduce
transmitted noise.
| Maintenance Data |
Engine oil and filter should be replaced every 10,000 km (6,000 miles).
The fuel filter should be changed every 20,000 km (12,000 miles). Valve
clearance adjustment is necessary every 20,000 km (12,000 miles);
standard cold clearances are 0.25 mm (0.010 inch) for both intake and
exhaust valves. Timing gear backlash and governor linkage should be
inspected periodically. Cooling system flushing and coolant replacement
are recommended every 2 years or 40,000 km (25,000 miles).
Compression pressure at cranking speed should be approximately 2,940 kPa
(426 psi) per cylinder, with a minimum allowable limit of 2,450 kPa (355
psi). Cylinder-to-cylinder variation should not exceed 490 kPa (71 psi).
Glow plug resistance should measure approximately 0.5 to 1.0 ohm. Oil
pressure warning should illuminate below 50 kPa (7 psi).
| Tightening Torques |
Cylinder head bolts: 49 Nm (36 lb-ft) initial, then 98 Nm (72 lb-ft)
final torque, followed by 90-degree angle tightening.
Main bearing cap bolts: 118 Nm (87 lb-ft).
Connecting rod bolts: 59 Nm (44 lb-ft) plus 90 degrees.
Flywheel bolts: 108 Nm (80 lb-ft) plus 90 degrees.
Crankshaft pulley bolt: 216 Nm (159 lb-ft).
Rocker cover bolts: 9 Nm (7 lb-ft).
Injector clamp bolts: 25 Nm (18 lb-ft).
Oil drain plug: 40 Nm (30 lb-ft).
Exhaust manifold nuts: 35 Nm (26 lb-ft).
Intake manifold bolts: 25 Nm (18 lb-ft).
Turbocharger mounting bolts: 45 Nm (33 lb-ft).
Glow plug: 15 Nm (11 lb-ft).
| Vehicle Applications |
The Mitsubishi 4D33 engine was installed in a wide range of commercial
and light-duty vehicles produced by Mitsubishi Fuso and its affiliates.
Major applications include:
– Mitsubishi Canter FE series (various models from early 1980s to 2000s)
– Mitsubishi Rosa minibus
– Mitsubishi Fuso light-duty trucks and small buses
– Agricultural and industrial machinery such as generators and
stationary power units
In turbocharged form, the 4D33 was particularly common in higher-GVWR
Canter models and small buses requiring additional torque for hill
climbing and heavy loads. The engine’s design longevity allows it to
remain in production and service in some markets even into the 2010s
under license manufacture.
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