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Kubota D850 Engine

General Technical Data

Kubota D850 Engine Specifications

Engine Model .......... Kubota D850
Engine Type .......... Vertical, water-cooled, 4-cycle diesel
Number of cylinders .......... 3
Bore, mm (in.) .......... 72.0 (2.83)
Stroke, mm (in.) .......... 70.0 (2.76)
Total displacement, cm3 (cu. in.) .......... 855 (52.2)
Gross power, kw (hp) .......... 14.9 (19.8)
Net power, kw (hp) .......... 13.4 (18.0)
Maximum speed, rpm .......... 3200
Idling speed, rpm .......... 800
Maximum torque, Nm (ft-lb) .......... 50.6 (37.3)
Torque speed, rpm .......... 1800
Combustion Chamber .......... Spherical type
Direction of rotation .......... Counter-clockwise
Compression ratio .......... 22:1
Firing order .......... 1-2-3

Fuel System

Fuel injection pump .......... Bosch K type mini pump
Injection nozzle .......... Bosch Throttle type
Injection timing, deg (rad) .......... 25 (0.44) before T.D.C.
Injection pressure, MPa (psi) .......... 13.7 (1990)
Governor .......... Centrifugal ball mechanical governor

Lubricating System

Lubricating system .......... Forced lubrication by pump
Oil pressure indicating .......... Electrical type switch
Oil filter .......... Full flow paper filter (cartridge type)

Electrical System

Starting system .......... Electric starting with starter
Starting Motor .......... 12V, 0.8 kW
Starting support device .......... By glow plug in combustion chamber
Battery .......... 12V, 65 AH
Dinamo for Charging .......... 12V, 150W

Dimensions

Length, mm (in.) .......... 475 (18.8)
Width, mm (in.) .......... 423 (16.7)
Height, mm (in.) .......... 566 (22.3)
Dry weight, kg (lbs.) .......... 82.6 (182.1)

Kubota D850 Maintenance Data

Fuel type .......... Diesel fuel No. 2-D
Engine oil type .......... SAE 10W-30
Engine oil capacity, L (qts) .......... 4.6 (4.9)
Coolant capacity, L (qts) .......... 4.6 (4.9)
Oil filter change interval .......... Every 100 hours
Oil change interval .......... Every 100 hours
Fuel filter change interval .......... Every 200 hours

Kubota D850 Service Specifications

Cylinder Block

Cylinder liner I.D., mm (in) ..........72.000-72.019 (2.8347-2.8354)
Oversized cylinder liner I.D., mm (in) ..........+ 0.5 (0.0197)
Clearance between tappet and guide, mm (in) ..........0.020-0.062 (0.0008-0.0024)
Tappet O.D., mm (in) ..........19.959-19.980 (0.7858-0.7866)
Tappet guide I.D., mm (in) ..........20.000-20.021 (0.7874-0.7882)
Clearance between rocker arm shaft and bearing, mm (in) ..........0.020-0.062 (0.0008-0.0024)
Rocker arm shaft O.D., mm (in) ..........10.973-10.984 (0.4320-0.4324)
Rocker arm bearing I.D., mm (in) ..........11.000-11.041 (0.4331-0.4347)
Camshaft side clearance, mm (in) ..........0.07-0.22 (0,0028-0.0087)
Camshaft alignment, mm (in) ..........0.01 (0.0004)
Cam height (Intake/Exhaust), mm (in) ..........26.88-26.83 (1.0583-1.0563)
Oil clearance of camshaft, mm (in) ..........0.050-0.091 (0.0020-0.0036)
Camshaft journal O.D., mm (in) ..........32.934-32.950 (1.2966-1.2972)
Camshaft bearing I.D., mm (in) ..........33.000-33.025 (1.2992-13002)
Connecting rod alignment, mm (in) ..........0.05 (0.0020)
Clearance between piston pin and small end bushing, mm (in) ..........0.014-0.038 (0.0006-0.0015)
Piston pin O.D., mm (in) ..........20.002-20.011 (0.7875-0.7878)
Small end bushing I.D., mm (in) ..........20.025-20.040 (0.7884-0.7890)

Cylinder Head

Cylinder head surface flatness, mm (in) ..........0.05 (0.0019)
Top clearance, mm (in) ..........0.6-0.8 (0.0237-0.0315)
Cylinder head gasket shim thickness, mm (in) ..........0.2 (0.0079)
Cylinder head gasket thickness (Free), mm (in) ..........1.15-1.30 (0.0453-0.0512)
Cylinder head gasket thickness (Tightened), mm (in) ..........1.05-1.15 (0.0413-0.0453)
Compression pressure, MPa (psi) ..........3.09-2.32 (448-337)
Valve clearance (Cold), mm (in) ..........0.145-0.185 (0.0057-0.0072)
Intake/exhaust valve seat width, mm (in) ..........2.12 (0.0835)
Intake/exhaust valve seat angle, deg (rad) ..........45 (0.785)
Intake/exhaust valve-face angle, deg (rad) ..........45.5 (0.794)
Valve recessing, mm (in) ..........0.9-1.1 (0.036-0.043)
Clearance between valve stem and valve guide, mm (in) ..........0.035-0.065 (0.0014-0.0025)
Valve stem O.D., mm (in) ..........6.960-6.975 (0.2741-0.2746)
Valve guide I.D., mm (in) ..........7.010-7.025 (0.2760-0.2765)
Intake valve (Open), deg (rad) ..........20 (0.35) before T.D.C
Intake valve (Close), deg (rad) ..........45 (0.79) after B.D.C
Exhaust valve (Open), deg (rad) ..........50 (0.87) before T.D.C
Exhaust valve (Close), deg (rad) ..........15 (0.26) after B.D.C
Valve spring free length, mm (in) ..........35.1-35.6 (1.382-1.401)
Valve spring tilt, mm (in) ..........1.3 (0.051)

Timing Gear

Timing gear backlash, mm (in) ..........0.042-0.115 (0.0017-0.0045)
Idle gear side clearance, mm (in) ..........0.20-0,51 (0.0079-0.0201)
Clearance between idle gear shaft and idle gear bushing, mm (in) ..........0.016-0.045 (0.0006-0.0018)
Idle gear shaft O.D., mm (in) ..........17.973-17.984 (0.7076-0.7080)
Idle gear bushing I.D., mm (in) ..........18.000-18.018 (0.7087-0.7054)

Piston and Piston Rings

Piston pin bore, mm (in) ..........20.000-20.013 (0.7874-0.7879)
Clearance between compression ring 2 and ring groove, mm (in) ..........0.085-0.112 (0.0033-0.0044)
Piston ring groove width, mm (in) ..........1.555-1.570 (0.0613-0.0618)
Compression ring 2 width, mm (in) ..........1.458-1.470 (0.0574-0.0579)
Clearance between oil ring and ring groove, mm (in) ..........0.020-0.055 (0.0008-0.0021)
Piston ring groove width, mm (in) ..........4.010-4.030 (0.1579-0.1587)
Oil ring width, mm (in) ..........3.975-3.990 (0.1565-0.1571)
Ring gap (Compression ring 1), mm (in) ..........0.25-0.40 (0.0098-0.0157)
Ring gap (Compression ring 2), mm (in) ..........0.25-0.40 (0.0098-0.0157)
Ring gap (Oil ring), mm (in) ..........0.25-0.40 (0.0098-0.0157)

Crankshaft

Crankshaft alignment, mm (in) ..........0.02 (0.0008)
Oil clearance between crankshaft and crankshaft bearing 1, mm (in) ..........0.034-0.106 (0.0013-0.0042)
Crankshaft O.D., mm (in) ..........43.934-43.950 (1.7297-1.7303)
Crankshaft bearing 1 I.D., mm (in) ..........43.984-44.040 (1.7317-1.7339)
Oil clearance between crankshaft and crankshaft bearing 2, mm (in) ..........0.034-0.092 (0.0013-0.0036)
Crankshaft O.D., mm (in) ..........43.934-43.950 (1.7297-1.7303)
Crankshaft bearing 2 I.D., mm (in) ..........43.984-44.026 (1.7317-1.7333)
Oil clearance between crank pin and crank pin bearing, mm (in) ..........0.029-0.087 (0.0011-0.0034)
Crank pin O.D., mm (in) ..........36.959-36.975 (1.4551-1.4557)
Crank pin bearing I.D., mm (in) ..........37.004-37.046 (1.4569-1.4585)
Crankshaft side clearance, mm (in) ..........0.15-0.31 (0.0059-0.0122)
Crankshaft sleeve wear, mm (in) ..........0.1 (0.0039)

Lubricating System

Engine oil pressure at idle speed, kPa (psi) ..........68 (10)
Engine oil pressure at rated speed, kPa (psi) ..........196-441 (29-64)
Clearance between inner rotor and outer rotor, mm (in) ..........0.11-0.15 (0.0043-0.0059)
Clearance between outer rotor and pump body, mm (in) ..........0,07-0.15 (0.0028-0.0059)
End clearance between inner rotor and cover, mm (in) ..........0.08-0.13 (0.0031-0.0051)

Fuel System

Injection timing, deg (rad) ..........23-25 (0.402-0.436) before T.D.C.
Fuel tightness of pump element, MPa (psi) ..........14.7 (2133)
Fuel tightness of delivery valve, MPa (psi) ..........14.7-13.7 (2133-1990)
Fuel injection pressure ..........13.73-14.71 (1991-2133)

Tightening Torque Specs

Head cover cap nuts (M7x1.0), Nm (ft-lb) .......... 6.9-8.8 (5.1-6.5)
Head screws and nuts (M9x1.25), Nm (ft-lb) .......... 64.7-69.6 (47.7-51.4)
Bearing case screws 1 (M7x1.0), Nm (ft-lb) .......... 26.5-30.4 (19.5-22.4)
Bearing case screws 2 (M8x1.25), Nm (ft-lb) .......... 29.4-34.3 (21.7-25.3)
Flywheel screws (M10x1.25), Nm (ft-lb) .......... 53.9-58.8 (39.8-43.4)
Connecting rod screws (M7x0.75), Nm (ft-lb) .......... 26.5-30.4 (19.5-22.4)
Rocker arm bracket nuts (M7x1.0), Nm (ft-lb) .......... 16.7-20.6 (12.3-5.2)
Idle gear shaft screws (M6x1.0), Nm (ft-lb) .......... 9.8-11.3 (7.2-8.3)
Glow plugs (M10x1.25), Nm (ft-lb) .......... 19.6-24.5 (14.5-18.1)
Drain plug (M12x1.25), Nm (ft-lb) .......... 39.2-49.0 (28.9-36.2)
Nozzle holder assembly (M24x2.0), Nm (ft-lb) .......... 29.4-49.0 (21.7-36.2)
Oil switch taper screw (PT-1/8), Nm (ft-lb) .......... 14.7-19.6 (10.8-14.5)
Fuel limit lock nut (M12x1.0), Nm (ft-lb) .......... 27.5-34.3 (20.3-25.3)
Fuel limit cap nut (M12x1.0), Nm (ft-lb) .......... 24.5-29.4 (18.1-21.7)
Injection pipe retaining nuts (M12x1.5), Nm (ft-lb) .......... 14.7-24.5 (10.8-8.1)
Nozzle holder and nozzle retaining nut, Nm (ft-lb) .......... 58.8-78.5 (43.4-57.9)
Nozzle holder mounting screw (M24x2.0), Nm (ft-lb) .......... 39.2-49.0 (28.9-36.2)
Crankshaft nut (M20x1.5), Nm (ft-lb) .......... 137.3-156.9 (101.3-115.7)

KUBOTA TRACTORS TROUBLESHOOTING
L235	L2501	L2550	L275	L3110
L3301	L35	L3710	L3901	L4310
L5030	M4700	M5700	M6040	M6800
M8200	M8540	M9000	MX5100	MX5200