Kubota Z482-E4B

Kubota Z482-E4BThe Kubota Z482-E4B is a 0.48 L (479 cc, 29.2 cu·in) straight-two, water-cooled naturally aspirated vertical diesel engine from the Super-Mini series manufactured by Kubota.

The Kubota Z482-E4B engine has a spherical type сombustion сhamber with glow plug, Bosch MD mini fuel injection pump, and Bosch throttle type injection nozzle.

Cylinder bore is 67.0 mm (2.64 in) and the piston stroke is 68.0 mm (2.68 in). The compression ratio rating is 23.5:1.

The Z482-E4B diesel engine produced 13.5 PS (9.9 KW; 13.3 HP) at 3,600 rpm of gross (intermittent) horsepower and 29.7 Nm (3.03 kg·m; 21.92 ft·lb) at 2,600 rpm of torque.

The breakdown of the engine code is as follows:

  • Z – 2-cylinders
  • 48 – Approximate displacement 480 cc
  • 2 – Super-Mini series
  • E4B – EPA/CARB Tier 4 (NRTC/NTE test mode) + EU Stage V

General information

Engine Specifications
Engine codeZ482-E4B
LayoutStraight-2, vertical diesel engine
Fuel typeDiesel fuel No.2-D
Displacement0.48 L, 479 cm3 (29.2 cu in)
Max. Horsepower Gross (intermittent): 13.5 PS (9.9 KW; 13.3 HP) at 3,600 rpm
Net (intermittent): 12.6 PS (9.3 KW; 12.5 HP) at 3,600 rpm
Torque output29.7 Nm (3.03 kg·m; 21.92 ft·lb) at 2,600 rpm
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
Firing order1-2
Dimensions (L x W x H):338 x 386 x 564 mm (13.3 x 15.2 x 22.2 in)
Weight53.0 kg (117.0 lbs)

Cylinder block

The Kubota Z482-E4B diesel engine has a high durability tunnel-type cylinder block in which the crank bearing component is a constructed body.

The crankshaft is made of tough special alloy steel, and the journals, pins and oil seal sliding portions are induction hardened. The front journal is supported by a solid type bearing, the intermediate journal by a split type, and the rear journal by a split type with thrust bearings. The crankshaft is provided with an oil gallery, through which engine oil is fed to the crankpin portion, and lubricate it.

The piston is made of aluminum alloy. Three rings are installed in grooves in the piston. The top ring is a keystone type, which can stand against heavy loads, and the barrel face on the ring fits well to the cylinder wall. The second ring is an undercut type, which effectively prevents the oil from being carried up. The oil ring has chamfered contact faces and anexpander ring, which increase the pressure of the oil ring against the cylinder wall.

Cylinder block
Compression ratio:23.5:1
Cylinder bore:67.0 mm (2.64 in)
Piston stroke:68.0 mm (2.68 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 groove clearance:Second0.090-0.120 mm (0.0035-0.0047 in)
Oil0.040-0.080 mm (0.0016-0.0031 in)
Piston ring end gap:Top0.120-0.270 mm (0.0047-0.0100 in)
Second0.300-0.450 mm (0.0118-0.0177 in)
Oil0.150-0.350 mm (0.0059-0.0130 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

The cross-flow type intake and exhaust ports in the Kubota Z482-E4B engine have their openings at both sides of the cylinder head. Because overlaps of intake and exhaust ports are smaller than in ports of other types which have openings on one side, the suction air can be protected from being heated and expanded by heated exhaust air.

Cylinder head
Valve Arrangement:OHV, gear drive
Valves:4 (2 valves per cylinder)
Valve timing:INTAKE Open: 25.5° B.T.D.C.
Close: 50.5° A.B.D.C.
EXHAUST Open: 55.5° B.B.D.C.
Close: 11.5° A.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:INTAKE31.300-31.800 mm (1.232-1.252 in)
EXHAUST31.300-31.800 mm (1.232-1.252 in)
Camshaft cam height:INTAKE26.880 mm (1.0583 in)
EXHAUST25.880 mm (1.0190 in)
Camshaft journal diameter:32.934-32.950 mm (1.2966-1.2972 in)

Tightening torque

Tightening torque specs
Cylinder head cover screw (M6x1.0):9.81-11.2 Nm (1.0-1.15 kgf-m, 7.24-8.31 ft-lbs)
Injection pipe retaining nut (M12x1.5):24.5-34.3 Nm (2.5-3.5 kgf-m, 18.1-25.3 ft-lbs)
Overflow pipe retaining nut (M12x1.5):19.6-24.5 Nm (2.0-2.5 kgf-m, 14.5-18.1 ft-lbs)
Nozzle holder assembly (M20x1.5):49.0-68.6 Nm (5.0-7.0 kgf-m, 36.2-50.6 ft-lbs)
Glow plugs (M8x1.0):7.8-14.7 Nm (0.8-1.5 kgf-m, 5.8-10.8 ft-lbs)
Rocker arm bracket nuts (M6x1.0):9.81-11.28 Nm (1.0-1.15 kgf-m, 7.23-8.32 ft-lbs)
Cylinder head screw (M8x1.25):37.3-42.2 Nm (3.8-4.3 kgf-m, 27.5-31.1 ft-lbs)
Fan drive pulley screw (M12x1.5):117.7-127.5 Nm (12.0-13.0 kgf-m, 86.8-94.0 ft-lbs)
Idle gear shaft mounting screw (M6x1.0):9.8-11.3 Nm (1.00-1.15 kgf-m, 7.2-8.3 ft-lbs)
Oil pump mounting screw (M8 x 1.25):17.7-21.6 Nm (1.80-2.20 kgf-m, 13.0-15.9 ft-lbs)
Connecting rod screw (M7x0.75):26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 ft-lbs)
Flywheel screw (M10x1.25):53.9-58.8 Nm (5.5-6.0 kgf-m, 39.8-43.4 ft-lbs)
Main bearing case screw 1 (M6x1.0):12.7-15.7 Nm (1.3-1.6 kgf-m, 9.4-11.6 ft-lbs)
Main bearing case screw 2 (M7x1.0):26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 ft-lbs)
Nozzle holder:34.3-39.2 Nm (3.5-4.0 kgf-m, 25.3-28.9 ft-lbs)

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
Standard2.85-3.23 MPa, 29-33 kgf/cm2, 413-469 psi
Allowable limit2.26 MPa, 23.0 kgf/cm2, 327 psi
Oil system
Recommended engine oilCF or CD,CE
SAE Viscosity NumberSAE 10W-30, 10W-40
Engine oil capacity Oil pan depth 101 mm (3.98 in): 2.1 L (2.2 US. qt, 1.85 Imp. qt.)
Oil pan depth 121 mm (4.76 in): 2.5 L (2.6 US. qt, 2.21 Imp. qt.)
Fuel system
Injection timing:18.25-19.75°B.T.D.C.
Injection nozzle pressure13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi)
Cooling system
Coolant capacity:2.8 liters (3.0 US.qts, 2.5 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)
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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