Kubota D640

Kubota D640The Kubota D640 is a 638 cc (38.9 cu·in) straight-tree, water-cooled naturally aspirated diesel engine manufactured by Kubota.

The Kubota D640 engine has a spherical type сombustion сhamber with a glow plug. The cylinder bore is 66.0 mm (2.60 in) and the piston stroke is 62.2 mm (2.45 in).

The Kubota D640 diesel engine produced 16.0 PS (11.8 KW; 15.8 HP) at 3,200 rpm of maximum horsepower.

The breakdown of the engine code is as follows:

  • D – 3-cylinders
  • 640 – Approximate displacement 640 cc

General information

Engine Specifications
Engine codeD640
LayoutStraight-3, vertical diesel engine
Fuel typeDiesel fuel No.2-D
Production
Displacement0.64 L, 638 cm3 (38.9 cu in)
Max. Horsepower16.0 PS (11.8 KW; 15.8 HP) at 3,200 rpm
Torque output
Injection typeIndirect injection
Cooling systemLiquid-cooled
Fuel systemFuel injection pump
Cooling systemWater with pressurized radiator
Starting systemElectric starting with 12V (0.7 kW) starter
Starting support deviceGlow plug in combustion chamber
GovernorCentrifugal ball mechanical governor
Power adderNone
Firing order1-2-3
Dimensions (L x W x H):
Weight

Cylinder block

Cylinder block
Compression ratio:
Cylinder bore:66.0 mm (2.60 in)
Piston stroke:62.2 mm (2.45 in)
Number of piston rings (compression / oil):2 / 1
Cylinder inner diameter:66.130-65.960 mm (2.6044-2.5984 in)
Piston skirt diameter65.906 mm (2.5957 in)
Piston ring side clearance:Second
Oil
Piston ring end gap:Top0.430-0.885 mm (0.0169-0.0348 in)
Second0.430-0.885 mm (0.0169-0.0348 in)
Oil
Piston pin outer diameter
Crankshaft main journal diameter: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:4 (2 valves per cylinder)
Valve timing:INTAKE
EXHAUST
Valve head diameter:INTAKE26.00 mm (1.0236 in)
EXHAUST22.50 mm (0.8858 in)
Valve stem diameter:INTAKE5.980 mm (0.2354 in)
EXHAUST5.980 mm (0.2354 in)
Valve seat angle:INTAKE45°
EXHAUST45°

Tightening torque

Tightening torque specs
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)
Connecting rod bolts (M7x1.0):26.0 Nm (2.6 kgf-m, 19.0 lb-ft)
Flywheel bolts (M10x1.25):59.0 Nm (6.0 kgf-m, 44.0 lb-ft)
Rocker arm bracket bolts (M6x1.0):11.5 Nm (1.15 kgf-m, 8.3 lb-ft)
Fan drive pulley bolt (M12x1.5):117.0 Nm (17.0 kgf-m, 86.0 lb-ft)
Oil pump mounting bolt (M8x1.25):20.0 Nm (2.0 kgf-m, 15.0 lb-ft)

Maintenance data

Valve clearance
Intake valve0.145-0.185 mm (0.0057-0.0073 in)
Exhaust valve0.145-0.185 mm (0.0057-0.0073 in)
Compression pressure
Standard2.24-3.10 MPa, 23-31 kgf/cm2, 325-450 psi
Oil system
Recommended engine oilCD or CE
SAE Viscosity NumberSAE 10W-30, 10W-40
Engine oil capacity3.0 liters (3.17 US.qts, 2.64 Imp. qts)
Oil filter typeFull-flow paper filter (cartridge)
Cooling system
TypeWater with pressurized radiator
Coolant capacity2.1 liters (2.22 US.qts, 1.85 Imp. qts)
Electrical system
Battery:12V, 35Ah or equivalent
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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