Mitsubishi K3E Specifications
| Engine Model: Mitsubishi K3E |
| Engine Type: 4-cycle inline 3-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 64.7 cu.in (1.06 L) |
| Rated Engine Power: 18.5 to 25 Hp (13.6 to 18.6 kW) at 2500 rpm |
| Fuel System Type: Indirect fuel injection |
____________________________________________________________________________________
The Mitsubishi K3E engine is a compact,
three-cylinder, four-stroke diesel powerplant designed for light
industrial and construction equipment. This engine is an evolution
within the K3 series, featuring a larger displacement than the K3C while
maintaining a similar overall architecture. It is engineered for
durability, fuel efficiency, and reliable operation in the demanding
environments of mini-excavators, compact loaders, and similar machinery.
The K3E features a water-cooled design, an indirect injection (swirl
chamber) combustion system, and a gear-driven camshaft. Constructed with
a cast iron cylinder block and head, it provides robustness and
effective heat dissipation. The engine is recognized for its
characteristic three-cylinder torque characteristics, mechanical
simplicity, and adaptability to various hydraulic drives and auxiliary
systems. Its design prioritizes serviceability and long-term reliability
in applications where accessibility for maintenance may be constrained.
Engine family: Mitsubishi K3 series.
Engine type: Inline-three cylinder, four-stroke diesel cycle, indirect
injection.
Displacement: 1061 cc (64.7 cubic inches).
Bore: 76.0 mm (2.992 inches).
Stroke: 78.0 mm (3.071 inches).
Compression ratio: 22:1-23:1.
Rated power output: 18.5 to 25 Hp (13.6 to 18.6 kW) at 2400-2600 rpm,
depending on application and governed speed.
Maximum torque output: 40-45 lb-ft (54-61 Nm) in the 1600-2000 rpm
range.
Firing order: 1-2-3.
Engine orientation: Variable; configured for specific equipment
installation.
Aspiration: Naturally aspirated.
Fuel type: Diesel fuel.
Recommended oil grade: SAE 10W-30 or 15W-40, meeting API CD or higher
specifications.
Oil capacity: 3.5 liters (3.7 U.S. quarts).
Coolant capacity: 4.0 liters (4.2 U.S. quarts) including radiator.
The cylinder block is a single, rigid casting from grey cast iron. This
material provides high strength, excellent vibration damping, and
longevity under continuous load. The block incorporates three cylinder
bores, cast integrally. The crankshaft is supported by four main
bearings. This bearing count ensures stable crankshaft operation and
manages the inherent secondary vibrations of a three-cylinder layout.
The crankshaft is a forged steel component with carefully calculated
counterweights to balance primary forces and moments. Main bearing caps
are cast iron and secured with two bolts each. Connecting rods are
forged from steel. Pistons are aluminum alloy, with a crown shape
designed for the indirect injection swirl chamber system. Each piston is
fitted with three rings: two compression rings and one oil control ring.
The block features integral water jackets and mounting bosses for
auxiliary equipment.
The cylinder head is a cast iron unit. It employs an overhead valve
(OHV) layout, with the camshaft located in the cylinder block. The
camshaft is driven by helical gears from the crankshaft, ensuring
precise timing and durability. Valve actuation follows a direct
mechanical path: camshaft lobe, tappet, pushrod, rocker arm, and valve.
The engine uses two valves per cylinder (one intake, one exhaust).
Valve clearance is adjusted manually via a screw and locknut on each
rocker arm. This adjustment is a required maintenance procedure. A
defining component is the swirl (pre-combustion) chamber for each
cylinder. This chamber is machined into the cylinder head and connected
to the main combustion chamber by a calibrated nozzle. This design
promotes thorough air-fuel mixing for cleaner combustion at a range of
engine speeds.
The fuel system is an indirect injection setup utilizing a mechanical,
distributor-type injection pump. This pump, often a Bosch or Zexel
model, is gear-driven from the engine camshaft. It functions as a single
pumping element that distributes high-pressure fuel sequentially to each
cylinder's injector via individual steel lines. The injectors are
pintle-type and are threaded directly into the pre-combustion swirl
chamber in the cylinder head.
A mechanical lift pump, either diaphragm or piston type, transfers fuel
from the tank to the injection pump. The system incorporates a
mechanical centrifugal governor integrated with the injection pump to
control maximum engine speed and provide stable idle. A hand primer pump
is fitted for bleeding air. Fuel filtration is handled by a primary
sedimentor/water separator and a replaceable paper secondary filter.
The lubrication system is a pressure-fed, full-flow filtration wet-sump
design. A trochoid-type (internal gear) oil pump is driven directly by
the crankshaft. Oil is drawn from the sump through a pickup tube and
strainer. The oil is then pressurized and forced through a full-flow,
spin-on or cartridge-type oil filter. From the filter, oil enters the
main gallery in the cylinder block.
It supplies the crankshaft's four main bearings and connecting rod
bearings via drilled passages. A separate drilled passage feeds oil to
the cylinder head to lubricate the rocker arm shaft, rocker arms, and
valve stems. The camshaft bearings in the block are lubricated from the
main gallery. A pressure relief valve maintains system pressure within
specification. Oil pressure is indicated by a gauge or warning light.
The cooling system is a pressurized, forced-circulation system. A
centrifugal water pump is belt-driven from the crankshaft pulley.
Coolant circulates through the block and head, governed by a wax-pellet
thermostat. The system employs a tube-and-fin radiator, often with a
shroud and a belt-driven fan. A pressure cap maintains system pressure
to elevate the coolant boiling point.
The air intake system uses a dry, replaceable paper air filter element,
sometimes with a pre-cleaner in dusty environments. The engine is
equipped with a mechanical decompression mechanism. This device,
actuated by a cable or lever, holds the exhaust valves slightly open to
reduce compression resistance for easier manual or electric starting,
especially in cold conditions. A 12-volt electric starter motor and an
alternator are standard.
The external dimensions of the K3E engine are compact, a necessity for
installation in confined machinery spaces like mini-excavator engine
bays. Approximate length is 600 mm (23.62 inches). Approximate width is
500 mm (19.69 inches). Approximate height is 650 mm (25.59 inches).
These dimensions are inclusive of standard ancillaries like the
injection pump and starter motor, but exclude equipment-specific mounts
and drives. The dry weight of the K3E engine is approximately 110-120 kg
(243-265 lbs), varying slightly with specific accessory configurations.
Engine oil and filter changes are required every 100-150 operating hours
or every 3 months, whichever comes first, under industrial service
conditions. The fuel filter element must be replaced every 200-250
operating hours. Air filter service is critical; the element should be
checked and cleaned every 50 hours, and replaced every 300 hours or more
frequently in dusty conditions.
Valve clearance inspection and adjustment is mandatory every 500
operating hours. Coolant should be drained, flushed, and refilled
annually. The fan belt tension must be checked and adjusted every 100
hours. Fuel injection timing and injector spray pattern/opening pressure
should be verified every 1000 operating hours. All grease fittings on
throttle and governor linkages require periodic lubrication.
Torque values are specified for clean, dry threads. Cylinder head bolts
are tightened in a specific sequence to 7.5-8.0 kgm (54-58 lb-ft / 74-78
Nm). Main bearing cap bolts: 6.5-7.0 kgm (47-51 lb-ft / 64-69 Nm).
Connecting rod cap bolts: 5.0-5.5 kgm (36-40 lb-ft / 49-54 Nm).
Crankshaft pulley bolt: 13.0-14.0 kgm (94-101 lb-ft / 127-137 Nm).
Fuel injection pump mounting bolts: 2.5-3.0 kgm (18-22 lb-ft / 25-29
Nm). Rocker arm shaft bracket bolts: 2.5-3.0 kgm (18-22 lb-ft / 25-29
Nm). Oil drain plug: 4.0-4.5 kgm (29-33 lb-ft / 39-44 Nm). Injector
holder clamp nut: 6.0-6.5 kgm (43-47 lb-ft / 59-64 Nm).
The Mitsubishi K3E engine is predominantly employed in compact
construction machinery. Its primary application is as the power unit for
various models of mini-excavators. Specific machine applications
include: Mitsubishi MS40, MS50, and MS60 series mini-excavators. Other
Japanese-brand mini-excavators from the 1980s and 1990s that sourced
Mitsubishi industrial engines.
Potential use in compact wheel loaders, trenchers, and stationary
equipment such as light-duty generators or water pumps. The engine's
compact size, three-cylinder configuration, and industrial-grade
durability made it a suitable choice for machinery where a reliable,
mechanically simple diesel engine in the 20-25 Hp range was required.
Production has ceased, but the engine remains supported by a parts
network for maintaining older equipment.
____________________________________________________________________________________
| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
