Mitsubishi S4E2 Specifications
| Engine Model: Mitsubishi S4E2 |
| Engine Type: 4-cycle inline 4-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 180.5 cu.in (2.96 L) |
| Rated Engine Power: 59 Hp (44.1 kW) at 2400 rpm |
| Fuel System Type: Indirect fuel injection |
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The Mitsubishi S4E2 is a four-cylinder diesel
engine representing a significant displacement increase within the S4E
series, engineered to deliver robust power and torque for demanding
industrial and agricultural applications. This 2.95-liter, naturally
aspirated power plant employs an indirect injection combustion system
with a swirl pre-combustion chamber, providing smooth combustion
characteristics, reduced operational noise, and reliable cold-starting
performance.
The four-cylinder configuration delivers inherent primary and secondary
mechanical balance, resulting in exceptionally low vibration levels, a
critical attribute for operator comfort in mobile machinery and stable
operation in generator sets. Its square bore and stroke design
contributes to balanced mechanical forces and a broad, flat torque curve
ideal for heavy cyclic loads. Constructed with a heavily reinforced cast
iron block and a gear-driven valve train, the S4E2 prioritizes
durability, serviceability, and long-term reliability, establishing
itself as a core power source for continuous-duty equipment in material
handling, construction, and power generation.
Manufacturer: Mitsubishi Heavy Industries, Ltd.
Engine Model: S4E2.
Engine Type: 4-cycle, water-cooled, vertical inline, indirect injection
diesel.
Aspiration: Naturally aspirated.
Emission Compliance: Manufactured in an era preceding stringent modern
regulations; conforms to historical industrial engine standards.
Management System: Mechanical fuel injection with mechanical governor.
Commonly equipped with a Bosch PES4-A series injection pump.
Number of Cylinders: 4.
Bore: 98 mm (3.858 in).
Stroke: 98 mm (3.858 in).
Displacement: 2.957 L (2957 cc) (180.5 cu in).
Compression Ratio: 19:1.
Firing Order: 1-3-4-2.
Rotation Direction: Counter-clockwise when viewed from the flywheel
side.
Maximum Gross Power Output: 44.1 kW (59 hp) at 2,400 rpm (representative
value; governed output is application-specific).
Maximum Gross Torque: 157 Nm (115.8 lb-ft) at 1,600 rpm.
Rated Speed: 2,200-2,400 rpm for variable-speed industrial use; 1,500 or
1,800 rpm for constant-speed generator applications. Idle Speed: 650-750
rpm.
The cylinder block is a massive, deeply ribbed casting manufactured from
high-grade gray iron. It employs a deep-skirt design that extends
substantially below the crankshaft centerline, creating an extremely
rigid foundation that minimizes block flex, damps vibration, and ensures
precise alignment of all internal components.
The cylinder bores are machined and honed directly into the block
material. The crankshaft is a forged steel component, supported by five
main bearings. This five-main-bearing support system is essential for
maintaining the alignment and minimizing deflection of the crankshaft
under high torque loads, directly contributing to smooth operation and
extended bearing and seal life.
Connecting rods are forged steel, fitted with replaceable precision
bearing shells at the crankpin end. The piston pin is a press-fit in the
connecting rod small end. Pistons are aluminum alloy, designed with a
specific crown profile compatible with the indirect injection swirl
chamber system. The piston ring pack consists of two compression rings
and one oil control ring.
A single-piece cast iron cylinder head is utilized, secured to the block
with high-tensile studs and nuts. The head accommodates one intake and
one exhaust valve per cylinder. Valve seat inserts are manufactured from
hardened, heat-resistant alloy to ensure longevity and maintain sealing
integrity under continuous thermal cycling. The valve train operates on
an overhead valve (OHV) design, with the camshaft located in the
cylinder block.
The camshaft is gear-driven from the crankshaft, a robust and
maintenance-free timing drive mechanism. The camshaft actuates the
valves via solid pushrods and rocker arms. Rocker arms are mounted on a
stationary shaft fastened to the cylinder head. Valve clearance is set
and maintained by a screw and locknut adjustment on each rocker arm, a
fundamental maintenance procedure. The cylinder head incorporates the
indirect injection pre-combustion (swirl) chamber for each cylinder,
which houses a glow plug for cold starting assistance.
The engine employs a mechanical, inline pump-line-nozzle fuel injection
system. The system is centered on a Bosch PES4-A or equivalent
multi-element inline injection pump. Core components include a
mechanical fuel lift pump, this injection pump, high-pressure steel fuel
lines, and throttle-type (pintle) injectors. The injection pump is a
jerk-pump design, driven by the engine's gear train. It supplies fuel at
high pressure to nozzles that discharge into the pre-combustion swirl
chamber.
A mechanical centrifugal governor, integral to the injection pump,
regulates engine speed by controlling the position of the fuel rack.
This governor is configurable for all-speed (variable) operation in
industrial machinery or precise constant-speed operation in generator
applications. Fuel filtration is a two-stage process, involving a
primary sedimentor/water separator and a secondary fine filter, both
critical for protecting the precision components of the injection
system.
Lubrication is provided by a high-capacity, forced-feed, full-flow wet
sump system. A trochoid (gear) type oil pump, driven directly from the
crankshaft, draws oil from the sump through a large-diameter pickup tube
equipped with a robust strainer screen. Pressurized oil is routed
through a full-flow, replaceable cartridge or canister-type oil filter.
After filtration, oil enters the main oil gallery in the block,
supplying the crankshaft main and connecting rod bearings, the camshaft
bearings, and the valve gear via internal passages and hollow pushrods.
The system is engineered for high flow and reliable pressure to ensure
adequate lubrication and cooling of all internal bearings. The specified
engine oil is API CC, CD, or CF grade. Total oil capacity is 6.0 liters
(6.3 US qt), including the filter. The oil pan is a heavy-duty stamped
steel or cast iron component.
Cooling is managed by a pressurized, pump-circulated liquid system. A
centrifugal water pump, driven by a V-belt from the crankshaft pulley,
provides forced coolant circulation. System operating temperature is
regulated by a wax-pellet type thermostat. Heat rejection occurs via a
large tube-and-fin radiator; the cooling fan is mounted on the engine
and is V-belt driven. The substantial displacement generates significant
thermal load, necessitating a high-capacity cooling system.
The cooling system requires a mixture of ethylene-glycol antifreeze and
clean water. A 50/50 mixture is standard for corrosion protection and
freeze resistance. Total cooling system capacity is 7.0 liters (7.4 US
qt) for the engine side, excluding the radiator and external hose
volume.
Intake System: Consists of an air cleaner (oil bath or dry element) and
a cast iron or aluminum intake manifold. Exhaust System: Comprises a
cast iron exhaust manifold and a downpipe connecting to the equipment's
exhaust silencer.
Electrical System: Operates on a 12V or 24V system, with 24V being
common for industrial starting applications. A corresponding starter
motor and alternator or DC generator are fitted. The engine incorporates
a glow plug system for cold starting, controlled by a key-switch or
timer module. An electric stop solenoid or manual cable acts on the
injection pump rack.
Governor: A mechanical centrifugal governor is standard, integrated
within the Bosch PES4-A injection pump. Configurable for variable or
constant-speed operation.
Length (Front Face of Block to Flywheel Housing): 783 mm (30.83 in).
Width (Overall): 511 mm (20.12 in).
Height (Overall, from sump to valve cover): 731 mm (28.78 in).
Dry Weight (with standard accessories): 270 kg (595 lb).
Engine Oil Change: Every 250 operating hours. Oil Filter Replacement:
Every oil change (250 hours). Fuel Filter Replacement: Service sediment
bowl daily; replace secondary filter element every 500 hours. Air
Cleaner Element Service: Clean oil bath or replace dry element every
100-250 hours, dependent on operational environment. Valve Clearance
Adjustment: Check and adjust every 500 operating hours.
Coolant Replacement: Drain, flush, and refill every 1,000 operating
hours or annually. Fan Belt Tension Check/Adjustment: Inspect and adjust
tension every 250 hours; replace belts showing signs of wear, glazing,
or cracking. Fuel Injection System Inspection: Have injection pressure,
spray pattern, and pump timing checked by a specialist every 1,500
hours.
Cylinder Head Nuts: Tighten in the specified multi-step crisscross
sequence to a final torque of 118-127 Nm (87-94 lb-ft). Main Bearing Cap
Bolts: 108-118 Nm (80-87 lb-ft).
Connecting Rod Cap Bolts: 78-88 Nm (58-65 lb-ft).
Flywheel to Crankshaft Bolts: 118-127 Nm (87-94 lb-ft).
Fuel Injector Holder: 59-69 Nm (44-51 lb-ft).
Glow Plugs: 15-20 Nm (11-15 lb-ft).
Oil Pan Drain Plug: 49-59 Nm (36-44 lb-ft).
Oil Filter Canister/Cartridge: For a canister, tighten the center bolt
to 25-30 Nm (18-22 lb-ft). For a spin-on filter, hand-tighten plus 3/4
turn after gasket contact.
0The Mitsubishi S4E2 engine was deployed in heavy-duty industrial and
agricultural equipment where its smooth four-cylinder power, substantial
torque, and indirect injection reliability were required. Common
applications include: Heavy-Duty Forklifts: Powers large container
handlers and high-capacity forklifts (7-12 ton range) from manufacturers
like Mitsubishi, Caterpillar, and Komatsu. Construction Equipment:
Mid-sized hydraulic excavators, large vibratory rollers, drilling rigs,
and mobile crushers. Generator Sets: A prime mover for industrial and
prime power generator sets in the 35-50 kVA power range.
Industrial Pumps: Drives high-volume pumps for firefighting, oil fields,
and major irrigation projects. Agricultural Tractors: Large utility and
agricultural tractors. Agricultural Machinery: Powers heavy implements
such as combine harvesters, forage harvesters, and large balers. Marine
Applications: Served as a propulsion engine for small tugs, fishing
vessels, and passenger ferries, and as a generator drive on larger
commercial vessels.
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