Yanmar TF70 Specifications
| Engine Model: Yanmar TF70 |
| 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: Direct injection |
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The Yanmar TF70 is a compact, horizontal,
single-cylinder, water-cooled diesel engine from the TF series, renowned
for its direct injection system and robust construction for light
agricultural and industrial applications.
The Yanmar TF70 is distinguished by its horizontal, single-cylinder
layout, which provides a low profile for easy installation in
space-constrained equipment like power tillers and water pumps. A
defining feature is its direct injection (DI) combustion system, which
atomizes fuel directly into the cylinder for higher thermal efficiency
and lower fuel consumption compared to older indirect injection (IDI)
models.
The engine operates as a 4-stroke cycle and relies on forced lubrication
via a trochoid pump to ensure reliability. It is available in manual
start (hand-crank) or optional electric start configurations. The Yanmar
TF70 is recognized for its heavy-duty cast iron construction and a
dual-shaft balancer system that significantly reduces operational
vibration, a major contributor to operator fatigue in hand-held or
walk-behind machinery.
Engine Type: Horizontal, single-cylinder, 4-stroke diesel
Displacement: 382 cc (23.3 cu.in)
Bore: 78.0 mm (3.07 in)
Stroke: 80.0 mm (3.15 in)
Compression Ratio: 18.1:1
Combustion System: Direct injection (Toroidal piston type)
Aspiration: Naturally aspirated
Firing Order: Single cylinder (fires once every 2 revolutions)
Direction of Rotation: Counter-clockwise (viewed from flywheel side)
Max Output: 5.2 kW (7.0 hp) @ 2,400 rpm
Continuous Rating: 4.5 kW (6.0 hp) @ 2,400 rpm
Max Torque: 24.3 Nm (17.9 lb-ft) @ 1,800 rpm
Fuel Injection Timing: 17° Before Top Dead Center (bTDC)
Injection Pressure: 19.6 MPa (200 kgf/cm2; 2,845 psi)
The cylinder block is manufactured from high-strength cast iron with a
horizontal orientation. It features an integral crankcase. The cylinder
bore is machined directly into the parent cast iron material.
A dual-shaft balancer system is integrated into the crankcase assembly
to cancel out primary vibrations. Lubrication oil level is checked via a
dipstick, with a filler port located on the valve cover or block.0
The cylinder head is a separate casting made of cast iron. It houses the
valves and the direct injection nozzle. The valvetrain is of the
overhead valve (OHV) type, operated by pushrods and rocker arms driven
by a camshaft located in the cylinder block. The engine utilizes 2
valves per cylinder (1 intake, 1 exhaust).
Valves: 2 total (1 intake, 1 exhaust)
Intake Valve Diameter: 34.0 mm (1.34 in)
Exhaust Valve Diameter: 30.0 mm (1.18 in)
Valve Seat Material: High-strength alloy steel inserts
The fuel system is a mechanical direct injection system utilizing a
Bosch-type in-line injection pump. The injection pump pressurizes fuel
and delivers it through a high-pressure pipe to the injection nozzle
installed in the cylinder head.
The system includes a fuel filter and a dedicated fuel tank with a
capacity of 7.1 to 9.0 liters. A centrifugal governor is integrated into
the injection pump assembly to maintain stable engine speed under
varying loads.
The lubrication system is a forced-feed design utilizing a trochoid-type
oil pump. The pump draws oil from the sump through a strainer,
pressurizes it, and passes it through a screen type filter (or optional
spin-on type). The pressurized oil is circulated to the crankshaft
bearings, connecting rod bearings, camshaft, and valve mechanism.
Oil Capacity (Total): 1.8 L (1.9 US qt)
Oil Capacity (Effective Sump): 0.6 L (0.63 US qt)
Recommended Oil Viscosity: SAE 30, 40, or 10W-30, API Class CC or CD
The cooling system is a liquid-cooled design, available either as a
Radiator type (M) or a Hopper tank type (H). A belt-driven centrifugal
water pump circulates coolant through the cylinder block and cylinder
head.
Coolant Capacity: 1.25 L (1.32 US qt)
Water Pump Type: Belt-driven centrifugal
Thermostat: Wax pellet type
| Intake and Exhaust Systems |
Intake System: Air is drawn through a cyclone-type, dual-stage air
cleaner with a replaceable paper element. A pre-cleaner removes large
debris before the main filter.
Exhaust System: The engine is equipped with a large-capacity muffler to
reduce operational noise levels.
0Overall Length: 607.5 mm (23.9 in)
Overall Width: 311.5 mm (12.3 in)
Overall Height: 469.0 mm (18.5 in)
Dry Weight (Manual Start): 67.5 kg (149 lb)
Dry Weight (Electric Start): 78.0 kg (172 lb)
Valve Clearance (Cold, Intake): 0.20 mm (0.008 in)
Valve Clearance (Cold, Exhaust): 0.20 mm (0.008 in)
Valve Inspection Interval: Every 500 operating hours
Engine Oil Change Interval: Every 100-150 operating hours
Oil Filter Cleaning: Every 200 hours (screen type)
Fuel Filter Cleaning: Every 200 hours
Coolant Change Interval: Every 1,000 hours (using anti-freeze)
Air Filter Element Cleaning: Every 50 hours (daily in dusty conditions)
Fuel Injection Nozzle Inspection: Every 1,000 hours
Cylinder Head Bolts: 49.0 - 54.0 Nm (36 - 40 lb-ft)
Connecting Rod Cap Bolts: 18.0 - 22.0 Nm (13 - 16 lb-ft)
Flywheel Bolts: 45.0 - 50.0 Nm (33 - 37 lb-ft)
Injection Nozzle Holder: 49.0 - 59.0 Nm (36 - 44 lb-ft)
Injection Pump Mounting Nuts: 10.0 - 12.0 Nm (89 - 106 in-lb)
The Yanmar TF70 engine was utilized across a wide range of light
industrial and agricultural machinery globally.
Hand Tractors / Power Tillers: Primary power source for two-wheel
tractors (e.g., Yanmar AG series).
Water Pumps: Centrifugal and diaphragm pump drives for irrigation and
dewatering.
Small Marine Propulsion: Used as an auxiliary engine for fishing boats.
Rice Transplanters: Power source for automatic seedling planting
machines.
Ground Monitoring Radar: Used as a battery charging engine in
GroundProbe slope stability radar systems for mining, frequently logging
over 15,000 hours of operation.
Threshers / Harvesters: Powering small-scale stationary agricultural
processing machinery.
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