Kubota D1803

Kubota D1803-MThe Kubota D1803-M is a 1.8 L (1,826 cc, 111.4 cu·in) straight-three, water-cooled naturally aspirated vertical diesel engine manufactured by Kubota.

The Kubota D1803-M-E engine has a spherical type сombustion сhamber (E-TVCS), the Bosch mini fuel injection pump. The cylinder bore and the piston stroke are 87.0 mm (3.43) in and 102.4 mm (4.04 in), respectively. The compression ratio rating is 23.8:1.

The D1803-M diesel engine produced 36.6 PS (26.9 KW; 36.1 HP) at 2,800 rpm of net horsepower.

The breakdown of the engine code is as follows:

  • D – 3-cylinders
  • 18 – Approximate displacement 1800 cc

General information

Engine Specifications
Engine codeD1803-M-E
LayoutStraight-3, vertical diesel engine
Fuel typeDiesel fuel No.2-D
Displacement1.8 L, 1,826 cm3 (111.4 cu in)
Fuel injection pumpBosch mini fuel injection pump
Fuel nozzle
Starting systemElectric starting with 12V (2.0 kW) starter
Starting support deviceGlow plug
GovernorCentrifugal mechanical governor
Power adderNone
Max. Horsepower Net (intermittent): 36.6 PS (26.9 KW; 36.1 HP) at 2,800 rpm
Net (continuous): 31.7 PS (23.3 KW; 31.2 HP) at 2,800 rpm
Torque output
Firing order1-2-3
Dimensions (L x W x H):576 x 499 x 685 mm (22.7 x 19.8 x 27.0 in)
Weight151.0 kg (330.0 lbs)

Cylinder block

Cylinder block
Compression ratio:23.8:1
Cylinder bore:87.0 mm (3.43 in)
Piston stroke:102.4 mm (4.04 in)
Number of piston rings (compression / oil):2 / 1
Cylinder inner diameter:87.000-87.022 mm (3.26772-3.26858 in)
Piston skirt diameter
Piston ring side clearance:Second0.093-0.128 mm (0.0037-0.0050 in)
Oil0.020-0.060 mm (0.0008-0.0023 in)
Piston ring end gap:Top0.200-0.400 mm (0.0080-0.0157 in)
Second0.300-0.450 mm (0.0118-0.0177 in)
Oil0.250-0.450 mm (0.0099-0.0177 in)
Piston pin outer diameter23.002-23.011 mm (0.9056-0.9059 in)
Crankshaft main journal diameter: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
Valve seat width:INTAKE2.120 mm (0.0835 in)
EXHAUST2.120 mm (0.0835 in)
Valve stem diameter:INTAKE7.960-7.975 mm (0.3134-0.3140 in)
EXHAUST7.960-7.975 mm (0.3134-0.3140 in)
Valve spring free length:INTAKE41.7-42.2 mm (1.6417-1.6614 in)
EXHAUST41.7-42.2 mm (1.6417-1.6614 in)
Camshaft cam height:INTAKE33.900 mm (1.3346 in)
EXHAUST33.900 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 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 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

Valve clearance
Intake valve0.18-0.22 mm (0.0071-0.0087 in)
Exhaust valve0.18-0.22 mm (0.0071-0.0087 in)
Compression pressure
Standard36.0-41.0 kgf/cm2 (3.53-4.02 MPa, 512-583 psi)
Oil system
Recommended engine oilCD or CE
SAE Viscosity NumberSAE 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:17-19° B.T.D.C.
Fuel injection pressure13.73-14.7 MPa (140-150 kgf/cm2, 1991-2133 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:5.8 liters (1.5 US gal, 1.3 Imp. gal)
Electrical system
Battery:12V, 100 or 120 Ah
Alternator brush Length (std/min):10.5 mm (0.4130 in) / 8.4 mm (0.3310 in)
Glow plug resistance:Approx 0.8 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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