Yanmar TS70 Specifications
| Engine Model: Yanmar TS70 |
| Engine Type: 4-stroke 1-cylinder horizontal water-cooled diesel |
| Total Displacement: 23.3 cu.in (0.38 L) |
| Rated Engine Power: 7 Hp (5.2 kW) at 2400 rpm |
| Fuel System Type: Indirect injection |
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The Yanmar TS70 is a compact, horizontal,
single-cylinder water-cooled diesel engine designed for small-scale
agricultural, industrial, and municipal applications where simplicity
and reliability are paramount. This engine belongs to the TS series,
which features an indirect injection system utilizing a swirl-type
pre-combustion chamber. The swirl chamber design produces smoother
combustion with lower pressure rise rates compared to direct injection
engines, reducing mechanical noise and vibration while extending
component life.
Operators in remote agricultural regions value the TS70 for its
tolerance to variable fuel quality, ease of manual starting through the
22.0 compression ratio, and straightforward field maintenance without
specialized diagnostic equipment. Common applications include small
water pumps for irrigation or flood control, portable rice milling
machines for post-harvest processing, light power tillers for soil
preparation in small farms, and stationary backup generators for rural
facilities.
The engine is available in two cooling configurations: the TS70H with an
open hopper tank for gravity-fed cooling using available water supplies,
and the TS70C with a radiator and forced circulation fan for
closed-system operation. Despite its small 0.382 Liter displacement, the
TS70 delivers 7.0 horsepower at 2,400 rpm, sufficient for continuous
operation of power take-off driven implements common in Southeast Asian
and South American agricultural markets.
Engine Type: Horizontal, 1-cylinder, 4-stroke diesel.
Displacement: 0.382 Liters (382 cc or 23.3 cu.in).
Bore x Stroke: 80 mm x 75 mm (3.15 in x 2.95 in).
Compression Ratio: 22.0:1.
Maximum Torque: 2.3 kg-m (16.6 lb-ft) achieved at 1,600 rpm.
Power Output Maximum: 5.2 kW (7.0 HP) at 2,400 rpm.
Power Output Continuous Rating: 4.4 kW (6.0 HP) at 2,400 rpm.
Direction of Rotation: Counter-clockwise viewed from the flywheel side.
Fuel Tank Capacity: 7.1 Liters (1.9 U.S. Gal) integral tank mounted
above the engine.
Governor: Mechanical centrifugal type.
Idle Speed: 800 rpm ±50 rpm.
Maximum No-Load Speed: 2,550 rpm governed.
Combustion System: Swirl type using a pre-combustion chamber separated
from the main cylinder by a narrow passage that generates high-velocity
air swirl to promote fuel-air mixing before ignition.
The cylinder block is a single-piece gray iron casting with an open-deck
design supporting a replaceable dry-type cylinder liner. The cylinder
sleeve is manufactured from centrifugally cast alloy iron with an
internal bore surface hardened to 300-350 HB for wear resistance against
piston ring friction. The block incorporates the crankcase, oil sump
mounting flange, and front and rear bearing supports in an integrated
monobloc construction.
A deep-skirt configuration extends below the crankshaft centerline,
providing rigid support for the single main bearing arrangement. The
cylinder head fastens to the block using four studs arranged
symmetrically around the bore. The block casting includes the intake and
exhaust ports on opposite sides, with separate passages for cooling
water entering from the hopper or radiator system.
A camshaft housing is cast into the side of the block, with an access
plate for camshaft removal without separating the crankcase halves. The
block includes mounting feet with rubber vibration isolators at four
positions for attachment to pump frames, tiller chassis, or generator
skids. Cast-iron construction absorbs vibration inherent in
single-cylinder operation, while the water jacket surrounding the
cylinder provides uniform temperature distribution and prevents
localized hot spots that would otherwise cause bore distortion at the
22.0 compression ratio.
The cylinder head is a separate cast-iron component fastened to the
block with four studs, incorporating the swirl-type pre-combustion
chamber as an integral cavity. The swirl chamber is a spherical cavity
connected to the main combustion chamber through a tangential passage
that creates high-velocity rotational flow during compression. A glow
plug is installed in the swirl chamber passage to assist cold starting
at temperatures below 10°C (50°F) by heating the incoming air charge
before fuel injection.
The valve arrangement consists of two overhead valves: one intake and
one exhaust, actuated by pushrods and rocker arms from the camshaft
located in the block. Intake valve diameter measures 34 mm (1.34 in).
Exhaust valve diameter measures 32 mm (1.26 in). Both valves are
manufactured from chrome-silicon steel with induction-hardened stem tips
and Stellite-faced seating surfaces. Valve seats are pressed-in powdered
metal inserts with an interference fit.
The overhead valve train uses a single rocker shaft with two rocker arms
operating each valve through adjustable screw-and-locknut tappets. Valve
clearances are critical to engine performance due to the high
compression ratio and swirl chamber design. Intake valve clearance
specification: 0.15 mm (0.006 in) cold. Exhaust valve clearance
specification: 0.20 mm (0.008 in) cold. The cylinder head gasket is a
copper-asbestos composite type with a steel fire ring around the
perimeter of the main combustion chamber opening, sealing against
pressures exceeding 50 bar (725 psi) during combustion.
The fuel system is an indirect injection design where fuel is injected
into the swirl chamber rather than directly into the main cylinder. The
injection pump is a single-plunger in-line type driven by a cam lobe on
the camshaft. Plunger diameter measures 6.5 mm with a 6 mm stroke,
delivering injection pressure of 120 bar (1,740 psi) at rated speed.
Fuel injection timing is fixed at 14 degrees before top dead center,
adjustable by shims behind the pump mounting flange.
The injector nozzle is a pintle-type single-hole unit mounted into the
swirl chamber casting, producing a cone-shaped fuel spray that interacts
with swirling air in the pre-chamber. Injector opening pressure is set
to 100 bar (1,450 psi) with needle lift of 0.25 mm. The pintle design
provides a self-cleaning action that prevents nozzle clogging when
operating on lower quality fuels.
A hand-operated priming lever on the injection pump body allows bleeding
air from the system after filter replacement or fuel depletion. The fuel
transfer function is integrated into the injection pump, drawing fuel
directly from the tank through a 40-micron mesh strainer located in the
fuel tank outlet. A clear fuel sediment bowl with water trap is
positioned between the tank and injection pump, allowing visual
inspection of fuel condition.
The swirl chamber combustion system is less sensitive to fuel cetane
number and viscosity than direct injection designs, allowing operation
on diesel fuel grades not meeting national specifications such as ASTM
D975 No. 2-D or EN 590. Fuel consumption at continuous rated output is
approximately 2.1 L/h (0.55 U.S. Gal/h) at 2,400 rpm.
The lubrication system uses a forced-feed design centered on a
trochoid-type oil pump mounted to the front of the camshaft. The inner
rotor of the trochoid pump is driven directly by the camshaft nose, with
the pump housing bolted to the crankcase front cover. The pump draws oil
through a fixed suction strainer positioned 5 mm above the bottom of the
oil pan, then delivers through a short passage to the main bearing and
camshaft bearing galleries.
Oil pressure at rated speed is maintained between 2.0 and 3.5 bar (29 to
51 psi) by a spring-loaded relief valve integrated into the pump
housing. Warm idle oil pressure is not less than 0.5 bar (7 psi). The
oil pan is a pressed steel construction attached to the crankcase
through a cork-rubber gasket. Oil capacity measures 2.0 Liters (2.1 U.S.
Qt) with the standard shallow sump. No oil filter is fitted to the TS70;
instead, a 0.2 mm mesh screen covers the pump intake strainer, and oil
changes are performed at shorter intervals to remove accumulated
contaminants.
A breather tube connects the crankcase to the intake port, drawing
combustion blow-by gases into the engine while maintaining crankcase
pressure slightly below atmospheric. Oil specification requires API
service classification CD or higher with SAE viscosity 30 for ambient
temperatures above 20°C (68°F) or SAE 20 for operating conditions
between 5°C and 20°C (41°F to 68°F). Oil change interval: 50 operating
hours under normal service, reduced to 25 hours under dusty conditions
or continuous high-load operation.
The cooling system is water-cooled with two distinct configurations. The
TS70H hopper version uses an open steel tank with 8.0 Liter (2.1 U.S.
Gal) capacity mounted directly above the cylinder head. Water circulates
by natural convection: heated water rises from the cylinder head water
jacket into the hopper, while cooler water flows downward from the
hopper into the block water jacket through a connecting pipe.
Evaporation losses require periodic refilling; operators refill the
hopper daily during continuous operation.
The TS70C radiator version employs a finned-tube cross-flow radiator
with 3.0 Liter (0.8 U.S. Gal) capacity mounted on the engine frame in
front of the cylinder. A belt-driven centrifugal water pump circulates
coolant through the block, head, and radiator at 25 Liters per minute
(6.6 U.S. Gal per minute) at rated speed. A pusher fan of 250 mm
diameter mounted between the radiator and engine draws air through the
radiator core. Both configurations use fresh water without antifreeze or
corrosion inhibitor, though a 5 to 10 percent soluble oil additive is
recommended for TS70C installations to prevent internal rusting.
Operating temperature for the TS70H hopper version is maintained by
controlling water level in the hopper, with normal operation at 85°C to
95°C (185°F to 203°F). The TS70C version includes an 82°C (180°F)
wax-pellet thermostat and a bypass circuit that diverts flow around the
radiator during warm-up. A warning whistle is installed on the hopper
filler neck, producing a steam-driven sound when water level drops below
safe operating limits.
| Intake and Exhaust Systems |
The air intake system incorporates a cyclone-type pre-cleaner followed
by an oil-bath air filter. Air enters the pre-cleaner tangentially,
spinning out larger dust particles, then passes through a reservoir of
engine oil where remaining fine particles adhere. The cleaned air then
travels through the intake manifold to the cylinder head. The oil-bath
filter requires cleaning every 25 hours in dusty operating conditions.
The exhaust system consists of a 25 mm diameter steel pipe with a spark
arrestor screen and rain cap for outdoor installation. Exhaust gas
temperatures at the manifold outlet reach 450°C (842°F) at rated power.
The starting system is entirely manual using a folding hand-crank
engaged with the flywheel through a ratcheting coupler. A decompression
lever lifts the exhaust valve off its seat during cranking, reducing
compression pressure from 22.0:1 to 6:1. The operator spins the
crankshaft to a speed of 60 to 80 rpm using the hand-crank, then
releases the decompression lever, allowing compression to ignite the
injected fuel. The automatic decompression mechanism returns the valve
to normal operation after the engine fires. The cranking handle is
stored on the engine frame when not in use.
The governor system is mechanical centrifugal type with flyweights
mounted on a rotating sleeve attached to the camshaft. Governor
flyweights move outward with increasing speed, sliding a control sleeve
that connects to the injection pump fuel rack through a linkage. The
governor maintains speed within 7 percent from no-load to full-load. A
spring-loaded speed control lever operated by a bowden cable allows the
operator to set desired engine speed between idle and maximum governed
speed.
Engine dry weight TS70H (hopper version): 73 kg (161 lb).
Engine dry weight TS70C (radiator version): 77 kg (170 lb).
Overall length TS70H: 633 mm (24.9 in) from hopper front to flywheel
rear face.
Overall width TS70H: 315 mm (12.4 in) at maximum including fuel tank and
hopper.
Overall height TS70H: 453 mm (17.8 in) from oil pan bottom to hopper
top.
Overall length TS70C: 710 mm (28.0 in) including radiator frontal
projection.
Overall width TS70C: 380 mm (15.0 in) including radiator side tanks.
Overall height TS70C: 550 mm (21.7 in) including radiator filler neck.
Crankshaft centerline height above oil pan rail: 120 mm (4.7 in).
Flywheel diameter: 280 mm (11.0 in) with 3-groove V-belt pulley.
PTO shaft extension length beyond flywheel: 70 mm (2.8 in) available for
implement connection.
0Oil change interval: 50 operating hours or every three months,
whichever arrives first. Oil filter not fitted; replace oil and clean
suction strainer at each change. Oil suction strainer cleaning: coincide
with each oil change using diesel fuel or kerosene to remove accumulated
sludge. Valve clearance inspection interval: 100 operating hours with
adjustment required if outside tolerances. Intake valve clearance: 0.15
mm (0.006 in) cold. Exhaust valve clearance: 0.20 mm (0.008 in) cold.
Fuel sediment bowl cleaning: 50 hours or weekly. Drain water and
sediment until clear fuel flows. Fuel strainer cleaning: 100 hours using
compressed air blown from inside outward. Air filter service: oil-bath
reservoir cleaning every 25 hours in dust conditions, 50 hours in clean
conditions. Replace filter element when damaged. Injector nozzle
inspection: 500 hours with opening pressure test at 100 bar (1,450 psi)
and spray pattern evaluation. Nozzle replacement recommended at 1,000
hours.
Injection pump plunger inspection: 1,000 hours, measure for wear
exceeding 0.05 mm (0.002 in) on plunger diameter. Cooling system service
TS70H: daily water level check, flush hopper every 200 hours to remove
scale. Cooling system service TS70C: coolant replacement every 500 hours
or annually. Glow plug check: 200 hours, measure resistance between
terminal and body, replace if open circuit or short circuit.
Decompression lever cable adjustment: 100 hours, ensuring cable free
play of 2 mm before lever actuation.
Cylinder head nuts: 45 Nm (33 lb-ft).
Connecting rod cap nut: 32 Nm (24 lb-ft)l.
Flywheel nut: 98 Nm (72 lb-ft).
Injection pump mounting nuts: 14 Nm (10 lb-ft).
Injector hold-down nut: 25 Nm (18 lb-ft).
High-pressure fuel line nut: 15 Nm (11 lb-ft).
Rocker arm shaft bracket bolts: 20 Nm (15 lb-ft).
Pushrod cover nuts: 8 Nm (71 lb-in).
Valve cover nuts: 8 Nm (71 lb-in).
Oil pan bolts: 12 Nm (9 lb-ft).
Water pump mounting bolts (TS70C): 14 Nm (10 lb-ft).
Cooling fan mounting bolts (TS70C): 10 Nm (89 lb-in).
Starter bracket bolts (if electric start option fitted): 20 Nm (15
lb-ft).
Governor lever pinch bolt: 6 Nm (53 lb-in).
Engine mounting bolts to frame: 30 Nm (22 lb-ft).
Flywheel guard bolts: 20 Nm (15 lb-ft).
The Yanmar TS70 serves as a stationary power unit for agricultural and
industrial implements rather than mobile on-road vehicles. Primary
applications include water pumps for field irrigation, flood mitigation,
and livestock watering. The engine mates directly to centrifugal pump
frames through a flexible coupling or V-belt drive, with pump capacities
typically of 200 to 500 Liters per minute (53 to 132 U.S. Gal per
minute) at 20 meter head. Small-scale rice milling machines utilize the
TS70 to drive hulling rollers and separating fans for post-harvest
processing in Asian farming villages.
Power tillers for soil preparation in wet rice paddies and dry field
cultivation are equipped with the TS70, transmitting power through a
transmission to two steel cage wheels. The engine appears in stationary
threshing machines for grains. Small generators of 3 kVA to 4 kVA output
at 220 V 50 Hz or 110 V 60 Hz are powered by the TS70 for rural
electrification, welding power, or battery charging stations. Additional
applications include oilseed expellers, small feed grinders, and coconut
dehusking machines.
The TS70H hopper version is preferred for applications with available
water supply and minimal maintenance support, such as remote village
water pumping or temporary irrigation. The TS70C radiator version is
selected for mobile applications like power tillers or for installations
requiring unattended operation without daily water refilling.
Classification society and industrial certifications are not applicable
to this engine, as it serves in unregulated agricultural and light
industrial sectors.
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