Mitsubishi 4D35 Specifications
| Engine Model: Mitsubishi 4D35 |
| Engine Type: 4-cycle inline 4-cylinder OHV 8-valve liquid-cooled diesel |
| Total Displacement: 278.3 cu.in (4.56 L) |
| Rated Engine Power: 138 Hp (103 kW) at 3500 rpm |
| Fuel System Type: Direct injection |
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The Mitsubishi 4D35 is a 4.6-liter, naturally
aspirated, inline four-cylinder diesel engine produced from approximately 1993
to 1999. It was developed as a robust and durable powerplant for medium-duty
commercial applications, finding its primary application within the Mitsubishi
Fuso Canter series of light trucks.
The engine was engineered during an era when mechanical reliability and ease of
service were paramount, and its design reflects these priorities through the use
of a gear-driven camshaft, a direct injection combustion system, and a cast-iron
cylinder block. The 4D35’s architecture is characterized by a long-stroke
design, which prioritizes low-end torque generation - a critical attribute for
vehicles operating in urban delivery cycles, construction sites, and other
environments requiring frequent stop-and-go operation under load.
Its reputation for durability is well-established within commercial fleets,
where units often accumulate high mileage with proper maintenance before
requiring major overhaul. The engine’s serviceability is enhanced by its
mechanical fuel system and the absence of complex electronic controls found in
later diesel generations, making it a preferred choice for operators in regions
where diagnostic equipment access may be limited.
The 4D35 engine represents the culmination of Mitsubishi’s philosophy for
commercial diesel engines in the 1990s, focusing on structural integrity,
thermal management, and sustained torque delivery. The engine’s inline-four
configuration with a 110 mm bore and 120 mm stroke yields a displacement of
4,560 cc, placing it in a class suitable for vehicles with gross vehicle weights
up to 5,900 kg. Its direct injection combustion system, paired with an overhead
valve (OHV) valvetrain featuring two valves per cylinder, provides a balance
between fuel efficiency and mechanical simplicity.
The gear-driven camshaft eliminates the maintenance concerns associated with
timing belts and reduces the risk of timing-related failures common in
chain-driven systems. The cylinder block is constructed from cast iron, a
material chosen for its superior vibration damping characteristics and its
ability to withstand the thermal and mechanical stresses of sustained high-load
operation.
The cooling system is designed with a water-cooled configuration, incorporating
a radiator, thermostat, and water pump to maintain consistent operating
temperatures across varying load conditions. While the engine lacks the
sophistication of modern common-rail turbocharged diesels, its straightforward
design translates to predictable maintenance costs and a high degree of field
repairability. The 4D35’s primary limitations are its power output, which is
modest by contemporary standards, and its noise and vibration levels, which are
more pronounced than those of newer, more refined diesel engines.
Production Period: 1993-1999.
Engine Code: 4D35.
Configuration: Inline four-cylinder (I4).
Displacement: 4,560 cc (278.3 cu.in).
Bore: 110.0 mm (4.33 in).
Stroke: 120.0 mm (4.72 in).
Firing Order: 1-3-4-2.
Compression Ratio: 18.5:1.
Combustion System: Direct injection.
Aspiration: Naturally aspirated.
Maximum Engine Speed: 3,500 rpm (governed).
Maximum Power: 103 kW (138 hp) @ 3,500 rpm.
Maximum Torque: 333 Nm (34.0 kgm / 246 lb-ft) @ 2,000-2,400 rpm.
The 4D35 cylinder block is manufactured from
high-strength cast iron, utilizing a deep-skirt design that extends below the
crankshaft centerline to provide increased rigidity and reduced vibration. The
block features a closed-deck construction at the top of the cylinder bores,
contributing to improved head gasket sealing and resistance to bore distortion
under high cylinder pressures. Five main bearings support the crankshaft, with
the bearing caps secured using high-tensile steel bolts to maintain crankshaft
alignment under load.
The cylinder bores are cast directly into the block and are finished with a
precision-honed surface to promote rapid piston ring seating and effective oil
control. The block incorporates the mounting provisions for the fuel injection
pump on the side, driven by the gear train at the front of the engine. Cast-in
coolant passages surround each cylinder bore to provide uniform cooling, while
the oil galleries are drilled directly into the block to supply pressurized
lubricant to the crankshaft, camshaft, and other critical components.
The cylinder head is constructed from cast iron,
selected for its thermal stability and compatibility with the cast-iron block to
ensure uniform expansion rates and reliable head gasket sealing. The overhead
valve (OHV) arrangement utilizes a gear-driven camshaft located within the
cylinder block, operating the valves through pushrods and rocker arms. Each
cylinder is served by two valves - one intake and one exhaust - with the valves
positioned to optimize the flow of incoming air and the evacuation of exhaust
gases.
The valve clearances are adjustable using a screw-and-locknut mechanism on the
rocker arms, requiring periodic maintenance to ensure proper engine operation
and prevent valve or seat damage. The cylinder head incorporates pre-combustion
chambers in some indirect injection variants of this engine family, but the 4D35
variant discussed here employs a direct injection system, with the combustion
chamber formed primarily within the piston crown. The cylinder head gasket is a
multi-layer steel design to withstand the high compression pressures and thermal
cycling inherent in diesel operation.
The fuel system utilizes a mechanical inline injection
pump, typically supplied by Bosch or Zexel, which is driven directly by the
engine’s gear train. The pump delivers fuel at high pressure through individual
high-pressure lines to each cylinder’s injector. The injection timing is
adjustable and must be set precisely to ensure optimal combustion efficiency,
power output, and emissions performance.
Fuel is drawn from the tank by a mechanical lift pump mounted on the cylinder
block, passed through a fuel filter with an integrated water separator, and
delivered to the injection pump. Excess fuel not injected during the combustion
cycle is returned to the fuel tank through a return line. The injectors are of
the nozzle-and-holder type, designed to atomize the fuel into a fine spray
pattern suitable for direct injection into the combustion bowl machined into the
piston crown. Regular maintenance includes replacement of the fuel filter and
periodic inspection of the injectors for proper spray pattern and opening
pressure.
The lubrication system employs a wet-sump design with a
gear-type oil pump mounted within the front timing gear case, driven directly by
the crankshaft. The pump draws oil from the sump through a screened pickup tube
and delivers it through a full-flow spin-on oil filter mounted externally on the
cylinder block. The filtered oil is distributed through internal galleries to
the crankshaft main bearings, connecting rod bearings, camshaft bearings, and
other moving components.
The rocker arm assembly receives oil through hollow pushrods or dedicated
passages depending on the configuration. A pressure relief valve is integrated
into the oil pump assembly to maintain consistent oil pressure and prevent
over-pressurization at higher engine speeds. An oil cooler, either water-to-oil
or air-to-oil depending on the vehicle application, is incorporated to manage
oil temperature during sustained high-load operation. Total system capacity,
including the filter and cooler, is approximately 9.0 liters (9.5 qt) for most
applications.
The cooling system is a pressurized water-cooled design
utilizing a crossflow radiator with a fin-and-tube core construction. A
centrifugal water pump, driven by the engine’s accessory drive belt, circulates
coolant through the cylinder block, cylinder head, and radiator. A wax-element
thermostat is positioned in the coolant outlet housing to regulate coolant flow
and maintain the engine within its optimal operating temperature range.
The system incorporates an expansion tank to accommodate coolant expansion
during operation and to facilitate the removal of air from the system. A
mechanical viscous fan or an electric fan, depending on the vehicle platform,
provides airflow across the radiator to dissipate heat during low-speed
operation and stationary idle.
The cooling system is designed to manage the significant thermal load generated
by the 4.6-liter displacement, particularly during sustained high-power
operation such as hill climbing or fully loaded urban delivery cycles. Coolant
capacity varies by vehicle application but generally ranges from 10.0 to 12.0
liters (10.6 to 12.7 qt).
| Intake and Exhaust Systems |
Intake System: The intake system consists of an air
cleaner housing with a replaceable dry-type filter element, ducting to the
intake manifold, and the intake manifold itself, which distributes air evenly to
each cylinder. The intake manifold is constructed from cast iron and is designed
with runners sized to optimize airflow velocity across the engine’s operating
range.
Exhaust System: The exhaust system utilizes a cast iron exhaust manifold
designed to withstand thermal cycling without warping. The exhaust gases are
directed through a single exhaust pipe to a silencer. Later production models
may incorporate emissions control components such as an exhaust gas
recirculation (EGR) system to reduce NOx emissions.
| Electrical and Starting System |
Electrical System: The engine is equipped with a
12-volt or 24-volt electrical system depending on the vehicle application. The
starter motor is a direct-drive or reduction-gear type, sized to provide
adequate cranking torque for the high compression ratio. The charging system
consists of an alternator with an internal voltage regulator to maintain battery
charge and supply electrical loads during operation.
Starting System: Glow plugs are installed in the cylinder head to assist with
cold starting. The glow plug system is controlled by a timer or electronic
control unit that activates the glow plugs for a predetermined duration based on
coolant temperature, ensuring reliable ignition during cold weather conditions.
Overall Length: 850 mm (33.5 in)
Overall Width: 650 mm (25.6 in)
Overall Height: 800 mm (31.5 in)
Dry Weight (complete engine): 300-350 kg (661-772 lbs)
Engine Oil: SAE 15W-40, 10W-30, or 5W-30 meeting API
CI-4 or higher classification for diesel engines. Oil Capacity (with filter
change): 9.0 L (9.5 qt). Oil Change Interval: 5,000-8,000 km (3,100-5,000 mi)
under normal conditions; shorter intervals under severe service. Fuel Filter:
Replace at 15,000-20,000 km (9,300-12,400 mi) intervals; water separator drain
as required.
Coolant Capacity: 10.0-12.0 L (10.6-12.7 qt) depending on vehicle platform.
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors; replace every 2 years or 40,000 km (24,800 mi). Valve Clearance
(Cold): Intake: 0.40 mm (0.016 in); Exhaust: 0.40 mm (0.016 in). Engine Idle
Speed: 650-750 rpm. Compression Pressure: Standard: 2.75 MPa (398 psi); Minimum
service limit: 1.96 MPa (284 psi); maximum variation between cylinders: 0.20 MPa
(29 psi).
Connecting Rod Cap Bolts: 100 Nm (74 lb-ft)
Main Bearing Cap Bolts: 175 Nm (129 lb-ft)
Cylinder Head Bolts: 175 Nm (129 lb-ft), additional 90°-105° turn
Flywheel/Flexplate to Crankshaft: 110-120 Nm (81-89 lb-ft)
Intake Manifold to Cylinder Head: 25-30 Nm (18-22 lb-ft)
Exhaust Manifold to Cylinder Head: 30-35 Nm (22-26 lb-ft)
Injection Pump Mounting Nuts: 20-25 Nm (15-18 lb-ft)
Injector Holders: 60-70 Nm (44-52 lb-ft)
Rocker Arm Shaft Brackets: 25-30 Nm (18-22 lb-ft)
Glow Plugs: 15-20 Nm (11-15 lb-ft)
Mitsubishi Fuso Canter
(6th Generation, 1993-1999)
FE Series: FE638G, FE638G(1), FE638G(3), FE638G(4) models with 2-ton and 3-ton
payload capacities.
FG Series: FG638E, FG638G four-wheel-drive variants.
Other Applications
Hyundai (Licensed Production): D4AF, D4AK, D4AE engines used in Hyundai Chorus,
County, Mighty, H250/350, HD65, and Dump 65/370 models; these are licensed
derivatives of the Mitsubishi 4D30-series engine family
Industrial Applications: The 4D35 engine and its derivatives have been utilized
in construction machinery (wheel loaders, excavators), agricultural equipment
(tractors), marine propulsion systems, and generator sets where its robust
construction and mechanical simplicity are valued.
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