Kubota D782

Kubota D782The Kubota D782 is a 0.78 L (778 cc, 47.5 cu·in) straight-three, water-cooled naturally aspirated diesel engine manufactured by Kubota.

The Kubota D782 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 24.0:1. Cylinder bore is 67.0 mm (2.64 in) and the piston stroke is 73.6 mm (2.9 in). The D782 diesel engine produced 19.2 PS (14.1 kW; 18.9 HP) at 3,200 rpm of gross (intermittent) horsepower.

The breakdown of the engine code is as follows:

  • D – 3-cylinders
  • 78 – Approximate displacement 780 cc

General information

Engine Specifications
Engine codeD782-E, -E2B, -E3B
LayoutStraight-3, vertical diesel engine
Fuel typeDiesel fuel No.2-D
Production
Displacement0.78 L, 778 cm3 (47.5 cu in)
Fuel injection pumpBosch MD type mini fuel injection pump
Fuel nozzleBosch throttle type
Starting systemElectric starting with 12V (0.8 kW) starter
Starting support deviceGlow plug in combustion chamber
GovernorCentrifugal ball mechanical governor
Power adderNone
Max. Horsepower19.2 PS (14.1 kW; 18.9 HP) at 3,200 rpm
Torque output
Firing order1-2-3
Dimensions (L x W x H):426 x 398 x 519 mm (16.8 x 15.7 x 20.4 in)
Weight63.7 kg (140.4 lbs)

Cylinder block

Cylinder block
Compression ratio:24.0:1
Cylinder bore:67.0 mm (2.64 in)
Piston stroke:73.6 mm (2.9 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:Second0.085-0.112 mm (0.0033-0.0044 in)
Oil0.020-0.060 mm (0.0008-0.0024 in)
Piston ring end gap:Top0.150-0.300 mm (0.0059-0.0118 in)
Second0.300-0.450 mm (0.0118-0.0177 in)
Oil0.150-0.300 mm (0.0059-0.0118 in)
Piston pin outer diameter20.002-20.011 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 Open: 20° B.T.D.C.
Close: 45° B.T.D.C.
EXHAUST Open: 50° B.T.D.C.
Close: 15° B.T.D.C.
Valve seat width:INTAKE2.120 mm (0.0835 in)
EXHAUST2.120 mm (0.0835 in)
Valve stem diameter:INTAKE5.968-5.980 mm (0.2349-0.2354 in)
EXHAUST5.968-5.980 mm (0.2349-0.2354 in)
Valve spring free length:INTAKE31.6 mm (1.2441 in)
EXHAUST31.6 mm (1.2441 in)
Camshaft lobe height:INTAKE26.88 mm (1.0583 in)
EXHAUST26.88 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 valve0.145-0.185 mm (0.0057-0.0073 in)
Exhaust valve0.145-0.185 mm (0.0057-0.0073 in)
Compression pressure
Standard2.84-3.24 MPa, 29-33 kgf/cm2, 412-469 psi
Oil system
Recommended engine oilCD or CE
SAE Viscosity NumberSAE 10W-30, 10W-40
Engine oil capacity3.6 L (3.8 US. qt, 3.17 Imp. qt.)
Fuel system
Injection timing: 16-18° B.T.D.C. for D778-E2B
16.25-17.75° B.T.D.C. for D778-E3B
Fuel injection pressure13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi)
Cooling system
Coolant capacity3.1 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)
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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2 Comments

  1. Kubota rates this engine at 17 hp sometimes and 21hp at other times …. So what is true ?? IN there GR2120 lawn tractor ???

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