Kubota D1503-DI

Kubota D1503-DIThe Kubota D1503-M-DI is a 1.5 L (1,499 cc, 91.44 cu·in) straight-three, water-cooled naturally aspirated vertical diesel engine manufactured by Kubota.

The Kubota D1503-M-DI engine has a Troiddal type сombustion сhamber (Direct Injection), the Bosch “K”-type mini mini fuel injection pump and Bosch “P”-type hole fuel injection nozzle. The cylinder bore and the piston stroke are 83.0 mm (3.27) in and 92.4 mm (3.64 in), respectively. The compression ratio rating is 20.0:1.

The D1503-M-DI diesel engine produced 32.0 PS (23.5 KW; 31.5 HP) at 2,800 rpm of net horsepower.

The breakdown of the engine code is as follows:

  • D – 3-cylinders
  • 15 – Approximate displacement 1500 cc
  • DI – Direct Injection

General information

Engine Specifications
Engine code D1503-M-DI
Layout Straight-3, vertical diesel engine
Fuel type Diesel fuel No.2-D
Production –
Displacement 1.5 L, 1,499 cm3 (91.44 cu in)
Fuel injection pump Bosch “K”-type mini injection pump
Fuel nozzle Bosch “P”-type hole
Starting system Electric starting with 12V (1.4 kW) starter
Starting support device Glow plug
Governor Centrifugal mechanical governor
Power adder None
Max. Horsepower Net (intermittent): 32.0 PS (23.5 KW; 31.5 HP) at 2,800 rpm
Gross (intermittent): 33.7 PS (24.8 KW; 33.3 HP) at 2,800 rpm
Torque output –
Firing order 1-2-3
Dimensions (L x W x H): 599 x 514 x 643 mm (23.6 x 20.2 x 25.3 in)
Weight 148.0 kg (326.0 lbs)

Cylinder block

Cylinder block
Compression ratio: 20.0:1
Cylinder bore: 83.0 mm (3.27 in)
Piston stroke: 92.4 mm (3.64 in)
Number of piston rings (compression / oil): 2 / 1
Cylinder inner diameter: 83.000-83.022 mm (3.2677-3.2686 in)
Piston skirt diameter –
Piston ring side clearance: Second 0.093-0.128 mm (0.0037-0.0050 in)
Oil 0.020-0.060 mm (0.0008-0.0023 in)
Piston ring end gap: Top 0.200-0.350 mm (0.0080-0.0138 in)
Second 0.300-0.450 mm (0.0118-0.0177 in)
Oil 0.250-0.450 mm (0.0099-0.0177 in)
Piston pin outer diameter 23.002-23.011 mm (0.9056-0.9059 in)
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 diameter: 46.959-46.975 mm (1.8487-1.8494 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 7.960-7.975 mm (0.3134-0.3140 in)
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)
EXHAUST 41.7-42.2 mm (1.6417-1.6614 in)
Camshaft cam height: INTAKE 33.900 mm (1.3346 in)
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 screw: 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 clamp screw: 25.5-29.5 Nm (2.4-2.8 kgf-m, 17.4-20.3 lb-ft)
Connecting rod screw: 44.1-49.0 Nm (4.5-5.0 kgf-m, 32.5-36.2 lb-ft)
Flywheel bolts: 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)

Maintenance data

70-80 Ah or equivalent

Valve clearance
Intake valve 0.18-0.22 mm (0.0071-0.0087 in)
Exhaust valve 0.18-0.22 mm (0.0071-0.0087 in)
Compression pressure
Standard 30.0-33.0 kgf/cm2 (2.94-3.24 MPa, 427-469 psi)
Oil system
Recommended engine oil CD or CE
SAE Viscosity Number SAE 10W-30, 10W-40
Engine 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)
Fuel system
Injection timing: 10.5-12.5° B.T.D.C.
Fuel injection pressure 1st stage: 18.6 MPa (190 kgf/cm2, 2702 psi)
2st stage: 22.6 MPa (230 kgf/cm2, 3270 psi)
Cooling system
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, 60A (75D31R)
Alternator brush Length (std/min): 10.5 mm (0.4130 in) / 8.4 mm (0.3310 in)
Glow plug resistance: Approx 1.0 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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