Mitsubishi KE70 Specifications
| Engine Model: Mitsubishi KE70 |
| Engine Type: 4-cycle 2-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 40.8 cu.in (0.67 L) |
| Rated Engine Power: 15 Hp (11.2 kW) at 2800 rpm |
| Fuel System Type: Indirect injection |
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The Mitsubishi KE70 is a vertical,
water-cooled, 4-stroke, 2-cylinder diesel engine. It is a vintage,
heavy-duty unit primarily used in compact Japanese tractors from the
1970s and 1980s, such as the Iseki TX1300 and Mitsubishi D1300. This
engine is a swirl chamber (indirect injection) design, which promotes
smoother and quieter operation compared to direct injection units of the
same era.
Renowned for its robust cast iron construction and mechanical
simplicity, the KE70 delivers modest power suited for light agricultural
tasks. Its long production run and extensive use across multiple brands,
including Bolens and Satoh, have established it as a reliable and easily
serviceable powerplant for compact utility tractors.
The Mitsubishi KE70 is a four-stroke, water-cooled, naturally aspirated,
inline 2-cylinder diesel engine. The cylinder arrangement is vertical
and in-line, designed for longitudinal mounting in compact tractor
frames. The engine block is constructed from cast iron, while the
cylinder head is also a cast iron unit. The valvetrain is an overhead
valve (OHV) design with pushrods and rocker arms, actuated by a camshaft
located in the cylinder block. Each cylinder features two valves - one
intake and one exhaust.
Displacement is 669 cc (40.8 cu.in) / (0.7 L), achieved through a bore
of 73.0 mm (2.87 in) and a stroke of 80.0 mm (3.15 in). The undersquare
design (stroke longer than bore) promotes torque production at lower
engine speeds, essential for drawbar and power take-off (PTO)
applications.
The combustion system is a swirl chamber (indirect injection) design.
The compression ratio is standard for this engine type, with factory
compression pressure specifications reaching up to 350-490 psig
depending on engine health and wear state. Power output is rated at 13
to 15 horsepower (9.7 to 11.2 kW) at 2,700 to 2,800 rpm. The firing
order for a 2-cylinder engine is 1-2.
The cylinder block is a cast iron, closed-deck design. This construction
provides high rigidity and excellent bore retention under thermal and
mechanical loads. The water jacket surrounds each cylinder bore fully,
promoting even cooling across the engine. The block is configured for
vertical mounting, with the engine mounts positioned on the sides of the
block.
The crankshaft is forged or cast nodular iron, supported by three main
bearings. The three-main-bearing configuration is standard for
2-cylinder engines, providing adequate support for the firing impulses.
Connecting rods are forged steel with a machined big end and a press-fit
piston pin bore. Pistons are aluminum alloy with two compression rings
and one oil-control ring. The piston skirts feature a coating to reduce
friction during cold starts. No cylinder liners are used in the base
block design; the bores are machined directly into the cast iron.
The cylinder head is a cast iron cross-flow casting with a swirl chamber
(pre-combustion chamber) design. The cross-flow arrangement places the
intake manifold on one side of the head and the exhaust manifold on the
opposite side, improving volumetric efficiency and reducing heat
transfer to the intake charge.
The camshaft is located in the cylinder block and actuates the valves
through mechanical lifters, pushrods, and rocker arms. The valve train
includes adjustable rocker arms with screw-type adjusters and locking
nuts, allowing precise valve clearance setting. Intake and exhaust
valves are fitted with hardened tip inserts to reduce wear at the rocker
arm contact point. Valve seats are induction-hardened directly into the
cast iron head. Valve guides are also integral to the head casting. The
cylinder head gasket is a composite or steel design.
The fuel system is a mechanical indirect injection system. An inline
injection pump (manufactured by Zexel or Diesel Kiki) is mounted to the
engine timing case and driven by a gear from the camshaft. The pump
generates high-pressure fuel pulses and distributes them to each
cylinder in the firing order (1-2). Injection timing is adjustable by
changing the thickness of shims between the pump and the engine block; a
common base starting point for the pump base minor diameter is 76 mm.
Fuel is delivered from the pump to the injectors through steel
high-pressure lines. The injectors are of the pencil type or pintle
nozzle design, specific to indirect injection engines. Each injector
opens at a precise pressure (120 bar or 1,740 psi), atomizing the fuel
into the swirl chamber in the cylinder head. The glow plug is located in
the swirl chamber, pre-heating the air to facilitate cold starting. A
manual primer pump is located on the injection pump or fuel filter head
to bleed air from the system after filter changes.
The lubrication system is a full-pressure, gear-type pump design. The
oil pump is mounted inside the oil pan or on the timing gear cover,
driven by a gear from the crankshaft. Oil is drawn through a screened
pickup and passed through the pump before being routed through a
full-flow spin-on oil filter.
Pressurized oil travels to main galleries machined into the cylinder
block, delivering to the crankshaft main bearings and connecting rod
bearings through drilled passages. A separate oil passage directs
pressurized oil upward through the cylinder block and cylinder head to
the rocker shaft assembly. The system includes a pressure relief valve.
Oil capacity is 2.6 liters (2.7 US qt).
The cooling system is a thermostatically controlled, pressurized liquid
cooling system with a belt-driven centrifugal water pump. The water pump
is mounted on the front of the cylinder block. Coolant is drawn from the
lower radiator tank, circulated through the cylinder block water jacket,
then through the cylinder head, and returned to the upper radiator tank.
A wax-pellet thermostat regulates coolant flow to maintain stable
operating temperatures. The thermostat opening temperature is either
76.5°C (169.7°F) or 82°C (179.6°F) depending on the specific tractor
variant. A fan draws air through the radiator core. The coolant system
capacity, including the engine block, heater core (if equipped), and
radiator, is 4.5 to 5.5 liters.
| Intake and Exhaust Systems |
Intake System: The intake system consists of a dry-type replaceable
paper air filter or an oil-bath air cleaner, depending on the tractor
variant, and a cast iron intake manifold. The air filter housing
includes a restriction indicator to signal when the filter element
requires cleaning or replacement.
Exhaust System: A cast iron exhaust manifold collects gases from both
cylinders. The system operates at elevated temperatures.
Electrical System: The engine is equipped with a 12-volt electrical
system. The starter motor is a gear-reduction type mounted to the
flywheel housing. The alternator or dynamo is a belt-driven unit with a
charging capacity of 15 to 30 amperes.
Governor System: A mechanical centrifugal governor is installed on all
tractor applications. The governor is driven by a gear from the camshaft
and adjusts the injection pump fuel rack to maintain a preset engine
speed regardless of load changes. Governor response is calibrated for
agricultural duty, providing droop characteristics that allow stable
operation of PTO-driven implements.
The Mitsubishi KE70 is a compact, light engine suited for small
tractors. Length, measured from the front pulley to the flywheel housing
mounting face, is 450 mm (17.7 in). Width, measured across the cylinder
head and injection pump, is 400 mm (15.7 in). Height from the bottom of
the oil pan to the top of the valve cover is 550 mm (21.6 in). The dry
weight of the complete engine assembly, including the flywheel, intake
and exhaust manifolds, injection pump, starter, and alternator, is 110
kg (242 lb).
Oil Capacity: With oil filter change, the crankcase capacity is 2.6
liters (2.7 US qt). Oil Filter: Spin-on full-flow filter. Replacement
interval coincides with each oil change. Oil Change Interval: Under
normal agricultural service, the engine oil and filter should be changed
every 100 operating hours or annually, whichever comes first. Engine
Coolant: A 50/50 mixture of ethylene glycol antifreeze and distilled
water is recommended. The cooling system capacity, including the
radiator, is approximately 5.0 liters (5.3 US qt).
Fuel Filter: Inline or spin-on fuel filter with sediment bowl.
Replacement interval is 500 operating hours or annually. Air Filter
Service: The oil-bath or dry-type air filter element should be inspected
and cleaned every 50 operating hours in dusty conditions. Valve
Clearance (Cold): Adjust with the engine at ambient temperature. Intake
valve clearance is 0.35 mm (0.014 in). Exhaust valve clearance is 0.35
mm (0.014 in).
Injection Pump Timing: Static timing is set by shim adjustment.
Injection timing marks are located on the pump flange and timing gear
case. Injector Opening Pressure: Pencil injectors open at approximately
120 bar (1,740 psi). Glow Plug Operation: Pre-heat for 5 to 10 seconds
before starting in cold weather. Glow plugs are activated by a key
switch position.
Cylinder Head Bolts: 128 to 137 Nm (94 to 101 lb-ft).
Connecting Rod Cap Nuts: 31 to 34 Nm (23 to 25 lb-ft).
Main Bearing Cap Bolts: 50 to 55 Nm (37 to 41 lb-ft).
Flywheel Housing to Cylinder Block Bolts: 40 Nm (30 lb-ft).
Flywheel to Crankshaft Bolts: 50 Nm (37 lb-ft).
Intake Manifold Nuts: 15 Nm (11 lb-ft).
Exhaust Manifold Nuts: 15 Nm (11 lb-ft).
Injection Pump Mounting Nuts: 20 Nm (15 lb-ft).
Injector Clamp Bolts (Hold-Down): 25 Nm (18 lb-ft).
High-Pressure Fuel Line Nuts: 25 Nm (18 lb-ft).
Glow Plugs: 15 Nm (11 lb-ft).
Valve Cover Bolts: 8 Nm (6 lb-ft).
Oil Pan Bolts: 12 Nm (9 lb-ft).
Oil Filter (Spin-On): 15 Nm (11 lb-ft) or 3/4 turn after gasket contact.
Water Pump Mounting Bolts: 15 Nm (11 lb-ft).
Thermostat Housing Bolts: 10 Nm (7 lb-ft).
Crankshaft Pulley Bolt: 80 Nm (59 lb-ft).
Starter Motor Mounting Bolts: 30 Nm (22 lb-ft).
Alternator Pivot and Adjustment Bolts: 20 Nm (15 lb-ft).
The Mitsubishi KE70 engine was utilized across a wide range of compact
tractors manufactured by Mitsubishi and other brands during the 1970s
and 1980s.
Mitsubishi Applications:
Mitsubishi D1300
Mitsubishi D1300D
Mitsubishi MT372
Mitsubishi MT372D
Mitsubishi S370
Mitsubishi 150 (Suzue branded)
Iseki Applications:
Iseki TX1300 series
Bolens Applications:
Bolens G152 (2-cylinder version)
Bolens G154 (2-cylinder version)
Satoh Applications:
Satoh ST1300
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