The Kubota D722-E4 is a 0.7 L (719 cc, 43.9 cu·in) straight-three, water-cooled naturally aspirated diesel engine manufactured by Kubota.
The Kubota D722-E4 engine has a spherical type сombustion сhamber with glow plug, Bosch MD mini fuel injection pump, and Bosch throttle type injection nozzle.
The compression ratio rating is 23.5:1. Cylinder bore is 67.0 mm (2.64 in) and piston stroke is 68.0 mm (2.68 in).
The D722-E4 diesel engine produced 18.1 PS (13.3 KW; 17.8 HP) at 3,600 rpm of stand-by output power.
The breakdown of the engine code is as follows:
- D – 3-cylinders
- 72 – Approximate displacement 720 cc
- 2 – Super-Mini series
- E4 – EPA/CARB Tier 4 (NRTC/NTE test mode) + Stage V ready
General information
| Engine Specifications | |
| Engine code | D722-E4 |
| Layout | Straight-3, vertical diesel engine |
| Fuel type | Diesel fuel No.2-D |
| Production | – |
| Displacement | 0.7 L, 719 cm3 (43.9 cu in) |
| Max. Horsepower |
Net (intermittent): 19.0 PS (14.0 KW; 18.8 HP) at 3,600 rpm Stand-by: 18.1 PS (13.3 KW; 17.8 HP) at 3,600 rpm Continuous: 16.6 PS (12.2 KW; 16.4 HP) at 3,600 rpm |
| Torque output | – |
| Injection type | Indirect injection |
| Cooling system | Liquid-cooled |
| Fuel injection pump | Bosch MD type mini fuel injection pump |
| Fuel nozzle | Bosch throttle type |
| Starting system | Electric starting with 12V (0.8 kW) starter |
| Starting support device | Glow plug in combustion chamber |
| Governor | Centrifugal ball mechanical governor |
| Power adder | None |
| Firing order | 1-2-3 |
| Dimensions (L x W x H): | 485 x 386 x 564 mm (19.1 x 15.2 x 22.2 in) |
| Weight | 88.0 kg (194.0 lbs) |
Cylinder block
| Cylinder block | ||
| Compression ratio: | 23.5:1 | |
| Cylinder bore: | 67.0 mm (2.64 in) | |
| Piston stroke: | 68.0 mm (2.68 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Cylinder inner diameter: | 67.000-67.019 mm (2.6378-2.6385 in) | |
| Piston skirt diameter | – | |
| Piston ring side clearance: | Second | 0.090-0.120 mm (0.0035-0.0047 in) |
| Oil | 0.040-0.080 mm (0.0016-0.0031 in) | |
| Piston ring end gap: | Top | 0.150-0.300 mm (0.0059-0.0118 in) |
| Second | 0.300-0.450 mm (0.0118-0.0177 in) | |
| Oil | 0.150-0.350 mm (0.0059-0.0130 in) | |
| Piston pin outer diameter | 20.002-20.011 mm (0.7875-0.7878 in) | |
| Crankshaft main journal diameter: |
Flywheel side: 43.934-43.950 mm (1.72969-1.73032 in) Other: 39.934-39.950 mm (1.5722-1.5728 in) |
|
| Crankpin diameter: | 33.959-33.975 mm (1.337-1.3376 in) | |
Cylinder head
| Cylinder head | ||
| Valve Arrangement: | OHV, gear drive | |
| Valves: | 6 (2 valves per cylinder) | |
| Valve timing: | INTAKE | – |
| EXHAUST | – | |
| Valve seat width: | INTAKE | 2.120 mm (0.0835 in) |
| EXHAUST | 2.120 mm (0.0835 in) | |
| Valve stem diameter: | INTAKE | 5.968-5.980 mm (0.2349-0.2354 in) |
| EXHAUST | 5.968-5.980 mm (0.2349-0.2354 in) | |
| Valve spring free length: | INTAKE | 31.6 mm (1.2441 in) |
| EXHAUST | 31.6 mm (1.2441 in) | |
| Camshaft lobe height: | INTAKE | 26.88 mm (1.0583 in) |
| EXHAUST | 25.88 mm (1.0583 in) | |
| Camshaft journal diameter: | 32.934-32.950 mm (1.2966-1.2972 in) | |
Tightening torque
| Tightening torque specs | |
| Head cover cap nuts (M6x1.0): | 3.9-5.3 Nm (0.4-0.6 kgf-m, 2.9-4.3 lb-ft) |
| Head bolts (M8x1.25): | 39.2-44.1 Nm (4.0-4.5 kgf-m, 28.9-32.5 lb-ft) |
| Main bearing case bolts 1 (M6x1.0): | 12.7-15.7 Nm (1.3-1.6 kgf-m, 9.4-11.6 lb-ft) |
| Main bearing case screw 2 (M7x1.0): | 26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 lb-ft) |
| Flywheel bolts (M10x1.25): | 53.9-58.8 Nm (5.5-6.0 kgf-m, 39.8-43.4 lb-ft) |
| Connecting rod bolts (M7x0.75): | 26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 lb-ft) |
| Rocker arm bracket nuts (M6x1.0): | 9.81-11.28 Nm (1.0-1.15 kgf-m, 7.23-8.32 lb-ft) |
| Idle gear shaft bolts (M6x1.0): | 9.8-11.3 Nm (1.00-1.15 kgf-m, 7.2-8.3 lb-ft) |
| Idle gear shaft screws (M6x1.0): | 9.8-11.3 Nm (1.00-1.15 kgf-m, 7.2-8.3 lb-ft) |
| Glow plugs (M8x1.0): | 7.8-14.7 Nm (0.8-1.5 kgf-m, 5.8-10.8 lb-ft) |
| Nozzle holder assembly (M20x1.5): | 49.0-68.6 Nm (5.0-7.0 kgf-m, 36.2-50.6 lb-ft) |
| Nozzle holder and nozzle retaining nut: | 58.8-78.5 Nm (6.0-8.0 kgf-m, 43.4-57.9 lb-ft) |
| Injection pipe retaining nuts: | 24.5-34.3 Nm (2.5-3.5 kgf-m, 18.1-25.3 lb-ft) |
Maintenance data
| Valve clearance | |
| Intake valve | 0.145-0.185 mm (0.0057-0.0073 in) |
| Exhaust valve | 0.145-0.185 mm (0.0057-0.0073 in) |
| Compression pressure | |
| Standard | 2.84-3.24 MPa, 29-33 kgf/cm2, 412-469 psi |
| Oil system | |
| Recommended engine oil | CD or CE |
| SAE Viscosity Number | SAE 10W-30, 10W-40 |
| Engine oil capacity |
Oil pan depth 101 mm (3.98 in): 3.2 L (3.38 US. qt, 2.82 Imp. qt.) Oil pan depth 121 mm (4.76 in): 3.8 L (4.00 US. qt, 3.31 Imp. qt.) |
| Fuel system | |
| Injection timing: | – |
| Fuel injection pressure | 13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi) |
| Cooling system | |
| Coolant capacity | 3.1 liters (3.3 US.qts, 2.7 Imp. qts) |
| Thermostat’s valve opening temperature: | 69.5-72.5°C (157.1-162.5°F) |
| Temperature at which thermostat completely opens: | 85°C (185°F) |
| Electrical system | |
| Battery: | 12V, 35Ah or equivalent |
| Starter mica undercut: | 0.5-0.8 mm (0.0197-0.0315 in) |
| Starter brush length: | 16.0 mm (0.6299 in) |
| Alternator (no-load voltage): | AC 20V at 5,200 rpm |
| Glow plug resistance: | Approx 0.9 Ω |
| Alternator stator resistance: | Less than 1.0 Ω |
| Alternator rotor resistance: | Less than 2.9 Ω |
| Alternator slip ring: | 14.4 mm (0.567 in) |
| Alternator brush Length: | 10.5 mm (0.413 in) |
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