Kubota D1503

Kubota D1503The Kubota D1503 is a 1.5 L (1,499 cc, 91.44 cu·in) natural aspirated three-cylinders four-stroke liquid-cooled internal combustion vertical diesel engine, manufactured by Kubota for general-purpose applications.

An 83.0 mm (3.27 in) cylinder bore and an 92.4 mm (3.64 in) piston stroke give the D1503 engine a total of 1,499 cc of displacement. The compression ratio rating is 23.0:1.

The D1503-M-E engine produced 31.0 PS (22.8 KW; 30.5 HP) at 2,800 rpm of the net (intermittent) horsepower and 27.0 PS (19.8 KW; 26.5 HP) at 2,800 rpm of net (continuous) horsepower.

The Kubota D1503-M-E features:

  • Spherical type combustion chamber (E-TVCS)
  • Bosch mini type fuel injection pump
  • Centrifugal mechanical governor
  • Forced lubrication by trochoid pump
  • Liquid cooling system forced circulation with water pump
  • Electric starter (12V, 1.4 kW)
  • Charing generator (12V, 480 W)

General information

Engine Specifications
Engine modelD1503-M-E
Engine type4-stroke, vertical, three-cylinders
Displacement1.5 L, 1,499 cm3, (91.44 cu·in)
Max. horsepower Net (intermittent): 31.0 PS (22.8 KW; 30.5 HP) at 2,800 rpm
Net (continuous): 27.0 PS (19.8 KW; 26.5 HP) at 2,800 rpm
Max. torque
Cooling systemLiquid-cooled
Lubricating systemForced lubrication by pump
Combustion chamberSpherical type
Fuel injection pumpBosch mini type
Injection nozzle
Fuel usedDiesel fuel No.2-D
Starting systemElectric starter (12V, 1.4 kW)
Starting support deviceGlow plug in combustion chamber
GovernorCentrifugal mechanical governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)572 x 507 x 643 mm (22.5 x 20.0 x 25.3 in)
Dry weight148.0 kg (326.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:23.0:1
Cylinder bore:83.0 mm (3.27 in)
Piston stroke:92.4 mm (3.64 in)
Cylinder internal diameter (standard):83.000-83.022 mm (3.2677-3.2686 in)
Number of piston rings (compression / oil):2/1
Connecting rod small end diameter (standard):25.025-25.040 mm (0.9852-0.9858 in)
Piston pin diameter:25.002-25.011 mm (0.9843-0.9847 in)
Side clearance (Second):0.093-0.120 mm (0.0037-0.0047 in)
Side clearance (Oil):0.020-0.060 mm (0.0008-0.0023 in)
Ring end gap (Top):0.200-0.350 mm (0.0080-0.0138 in)
Ring end gap (Second):0.300-0.450 mm (0.0118-0.0177 in)
Ring end gap (Oil):0.250-0.450 mm (0.0099-0.0177 in)
Number of main bearings:4
Crankshaft main journal diameter: S/n below 3R9999: 51.921-51.940 mm (2.0441-2.0449 in)
S/n above 3S0001: 59.921-59.940 mm (2.3590-2.3598 in)
Crankpin journal diameter:46.959-46.975 mm (1.8487-1.8494 in)
Cylinder head
Valves:2 (6 valves in total)
Valve seat width (INTAKE):2.120 mm (0.0835 in)
Valve seat width (EXHAUST):2.120 mm (0.0835 in)
Value seat angle (INTAKE):60°
Value seat angle (EXHAUST):45°
Value face angle (INTAKE):60°
Value face angle (EXHAUST):45°
Valve steam diameter (INTAKE):7.960-7.975 mm (0.3134-0.3140 in)
Valve steam diameter (EXHAUST):7.960-7.975 mm (0.3134-0.3140 in)
Valve spring free length (INTAKE):41.7-42.2 mm (1.6417-1.6614 in)
Valve spring free length (EXHAUST):41.7-42.2 mm (1.6417-1.6614 in)
Camshaft cam height (INTAKE):33.900 mm (1.3346 in)
Camshaft cam height (EXHAUST):33.900 mm (1.3346 in)
Camshaft journal diameter :39.934-39.950 mm (1.5722-1.5728 in)

Tightening torque

Tightening torque specs
Rocker arm bracket nuts:23.5-27.5 Nm (2.4-2.8 kgf-m, 17.4-20.3 lb-ft)
Cylinder head:93.1-98.0 Nm (9.5-10.0 kgf-m, 68.7-72.3 lb-ft)
Nozzle holder assembly:49.0-68.6 Nm (5.0-7.0 kgf-m, 36.2-50.6 lb-ft)
Connecting rod screw:44.1-49.0 Nm (4.5-5.0 kgf-m, 32.5-36.2 lb-ft)
Flywheel:98.1-107.9 Nm (10.0-11.0 kgf-m, 72.3-79.6 lb-ft)
Main bearing case screw 1:46.1-50.9 Nm (4.7-5.2 kgf-m, 34.0-37.6 lb-ft)
Main bearing case screw 2:68.6-73.5 Nm (7.0-7.5 kgf-m, 50.6-54.2 lb-ft)

Service Data

Maximum speed:3,000 rpm
Idle speed:700-750 rpm
Cylinder compression:36.0-41.0 kgf/cm2 (3.53-4.02 MPa, 512-583 psi)
Compression differential limit between cylinders:10% or less
Valve clearance
Intake valve clearance:0.18-0.22 mm (0.0071-0.0087 in)
Exhaust valve clearance:0.18-0.22 mm (0.0071-0.0087 in)
Oil system
Lubrication system:Forced lubrication by trochoid pump
Oil type:API CD or better
Oil capacity: Oil pan depth 90.0 mm (3.54 in): 5.6 L (1.5 US gal, 1.2 Imp. gal)
Oil pan depth 124.0 mm (4.88 in): 7.0 L (1.8 US gal, 1.5 Imp. gal)
Oil filter:Full flow paper filter (cartrige type)
Fuel system
Fuel injection pumpBosch mini pump
Injection timing:17-19° B.T.D.C.
Fuel injection pressure13.73-14.7 MPa (140-150 kgf/cm2, 1991-2133 psi)
Cooling system
Type:Pressurized radiator (not included in the basic engine), forced circulation with water pump
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)
Coolant capacity:5.5 liters (1.5 US gal, 1.2 Imp. gal)
Electrical system
Battery:12V, 70-80 Ah or equivalent
Alternator brush Length (std/min):10.5 mm (0.4130 in) / 8.4 mm (0.3310 in)
Glow plug resistance:Approx 0.9 Ω
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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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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