________________________________________________________________________________

Kubota F2503 Engine

General Technical Data

Kubota F2503 Engine Specifications

Engine model ................ Kubota F2503
Engine type ................ 4-Stroke five-cylinder water-cooled diesel
Number of cylinders ................ 5
Total displacement ................ 2.49 L (152.7 cu.in)
Engine bore ................ 83.0 mm (3.27 in)
Engine stroke ................ 92.4 mm (3.64 in)
Gross power ................ 56.5 kW (75.6 Hp)
Net power ................ 52.2 kW (70.0 Hp)
Maximum speed ................ 2800 rpm
Idle speed ................ 750-850 rpm
Firing order ................ 1-3-5-4-2
Compression ratio ................ 22:1
Direction of rotation ................ Counterclockwise
Lubrication system ................ Forced lubrication by trochoid pump
Oil filter type ................ Full flow paper filter (cartridge)
Cooling system ................ Pressurized radiator, forced circulation with water pump
Electrical system rating ................ 12V
Starting system ................ Electric starter

Fuel System

Injection pump ................ Bosch type mini pump
Injection nozzle ................ Bosch throttle type
Injection pressure ................ 13.73 MPa (1991 psi)
Injection timing (Before TDC) ................ 0.333 rad (19 deg)
Governor type ................ Mechanical

Dimensions and Weight

Overall length ................ 779 mm (30.7 in)
Overall width ................ 520 mm (20.5 in)
Overall height ................ 739 mm (29.1 in)
Net weight ................ 227 kg (501 lbs)

Kubota F2503 Maintenance Data

Cylinder Block and Valves

Cylinder bore inside diameter (maximum) ................ 83.150 mm (3.2736 in.)
Cylinder compression ................ 3.53-3.72 MPa (512-540 psi)
Cylinder head (max. out of flatness) ................ 0.05 mm (0.002 in)
Intake valve clearance (Cold) ................ 0.18-0.22 mm (0.007-0.009 in.)
Exhaust valve clearance (Cold) ................ 0.18-0.22 mm (0.007-0.009 in.)

Engine Oil and Filters

Engine oil type ................ SAE 10W-30, 10W-40
API service classification ................ CD, CF or CE
Engine oil capacity ................ 7.9 L (8.3 qts)
Oil filter part number ................ 16414-32434
Fuel filter part number ................ 1C011-43014
Air filter part number ................ TA040-93230/TA040-93220

Service Intervals

Check Air Filters ................ Every 100 hours
Change Engine Oil ................ Every 200 hours
Change Engine Oil Filter ................ Every 200 hours
Replace Fuel Filter ................ Every 400 hours
Clean Air Filters ................ Every 400 hours
Replace Fan Belt ................ Every 500 hours
Check and Adjust Valve Clearance ................ Every 800 hours
Replace Air Filters ................ Annually

Kubota F2503 Service Specifications

Cylinder Block

Cylinder Bore I.D. (Std) ................ 83.000-83.022 mm (3.26772-3.26858 in.)
Cylinder Bore I.D. (Oversize) ................ 83.500-83.522 mm (3.28740-3.28827 in.)
Crankshaft Alignment – 0.02 mm (0.00079 in.)
Crankshaft Journal to Bearing 1 Oil Clearance ................ 0.040-0.118 mm (0.00157-0.00465 in.)
Crankshaft Journal to Bearing 2 Oil Clearance ................ 0.040-0.104 mm (0.00157-0.00409 in.)
Crankshaft Journal O.D ................ 59.921-59.940 mm (2.35910-2.35984 in.)
Crankshaft Bearing 1 I.D ................ 59.980-60.039 mm (2.36142-2.36374 in.)
Crankshaft Bearing 2 I.D ................ 59.980-60.025 mm (2.36142-2.36319 in.)
Crankpin to Crankpin Bearing Oil Clearance ................ 0.025-0.087 mm (0.00098-0.00343 in.)
Crankpin O.D ................ 46.959-46.975 mm (1.84878-1.84941 in.)
Crankpin Bearing I.D ................ 47.000-47.046 mm (1.85039-1.85221 in.)
Crankshaft Side Clearance (Std) ................ 0.15-0.31 mm (0.0059-0.0122 in.)
Crankshaft Side Clearance (Wear Limit) ................ 0.50 mm (0.0197 in.)
Camshaft Side Clearance ................ 0.07-0.22 mm (0.0028-0.0087 in.)
Camshaft Alignment ................ 0.01 mm (0.0004 in.)
Camshaft Journal to Cylinder Block Bore Oil Clearance ........ 0.050-0.091 mm (0.00197-0.00358 in.)

Cylinder Head and Valves

Cylinder Head Surface Flatness ................ 0.05 mm / 500 mm (0.002 in. / 19.7 in.)
Valve Clearance (Cold) ................ 0.18-0.22 mm (0.0071-0.0086 in.)
Top Clearance ................ 0.55-0.70 mm (0.0217-0.0276 in.)
Valve Stem to Valve Guide Clearance ................ 0.040-0.070 mm (0.0016-0.0027 in.)
Valve Stem O.D ................ 7.960-7.975 mm (0.31339-0.31398 in.)
Valve Guide I.D ................ 8.015-8.030 mm (0.31555-0.31614 in.)
Valve Seat Width (Intake/Exhaust) ................ 2.12 mm (0.0835 in.)
Valve Seat Angle (Intake) ................ 1.05 rad (60 deg)
Valve Seat Angle (Exhaust) ................ 0.79 rad (45 deg)
Valve Spring Free Length ................ 41.7-42.2 mm (1.6417-1.6614 in.)
Cam Height (Intake) ................ 33.890-33.910 mm (1.3343-1.3350 in.)
Cam Height (Exhaust) ................ 33.463-33.483 mm (1.3174-1.3182 in.)

Piston and Piston Rings

Piston Pin Bore I.D (Std) ................ 25.000-25.013 mm (0.98425-0.98476 in.)
Piston Pin Bore I.D (Wear Limit) ................ 25.05 mm (0.9862 in.)
Piston Pin O.D ................ 25.002-25.011 mm (0.98433-0.98469 in.)
Piston Pin to Small End Bushing Oil Clearance ................ 0.014-0.038 mm (0.00056-0.00150 in.)
Piston Pin Small End Bushing I.D ................ 25.025-25.040 mm (0.98524-0.98583 in.)
Second Ring Groove Clearance (Std) ................ 0.093-0.123 mm (0.0037-0.0048 in.)
Second Ring Groove Clearance (Wear Limit) ................ 0.20 mm (0.0079 in.)
Oil Ring Groove Clearance (Std) ................ 0.020-0.052 mm (0.0008-0.0020 in.)
Oil Ring Groove Clearance (Wear Limit) ................ 0.15 mm (0.0059 in.)
Top Ring End Gap (Std) ................ 0.30-0.45 mm (0.0118-0.0177 in.)
Second Ring End Gap (Std) ................ 0.30-0.45 mm (0.0118-0.0177 in.)
Oil Ring End Gap (Std) ................ 0.25-0.45 mm (0.0098-0.0177 in.)
Ring End Gap (Wear Limit) ................ 1.25 mm (0.0492 in.)

Timing Gear

Crank Gear to Idle Gear Backlash ................ 0.0415-0.1122 mm (0.00163-0.00442 in.)
Idle Gear to Cam Gear Backlash ................ 0.0415-0.1154 mm (0.00163-0.00454 in.)
Idle Gear to Injection Pump Gear Backlash ................ 0.0415-0.1154 mm (0.00163-0.00454 in.)
Crank Gear to Oil Pump Gear Backlash ................ 0.0415-0.1090 mm (0.00163-0.00429 in.)
Idle Gear Side Clearance ................ 0.12-0.48 mm (0.0047-0.0189 in.)
Idle Gear Shaft to Idle Gear Bushing Oil Clearance ................ 0.025-0.066 mm (0.00098-0.00260 in.)
Idle Gear Shaft O.D ................ 37.959-37.975 mm (1.49445-1.49508 in.)
Idle Gear Bushing I.D ................ 38.000-38.025 mm (1.49606-1.49705 in.)

Kubota F2503 Tightening Torque Specs

Cylinder head cover screw (M6x1.0), Nm (lb-ft) ................ 6.9-11.3 (5.1-8.32)
Cylinder head cover cap nut (M8x1.25), Nm (lb-ft) ................ 6.9-8.8 (5.1-6.5)
Cylinder head screw (M11x1.25), Nm (lb-ft) ................ 93.2-98.1 (68.7-72.3)
Injection pipe retaining nut (M12x1.5), Nm (lb-ft) ................ 24.5-34.3 (18.1-25.3)
Nozzle holder assembly (M20x1.5), Nm (lb-ft) ................ 49.0-68.6 (36.2-50.6)
Overflow pipe assembly retaining nut (M12x1.5), Nm (lb-ft) ................ 19.6-24.5 (14.5-18.1)
Glow plug (M10x1.25), Nm (lb-ft) ................ 19.6-24.5 (14.5-18.1)
Rocker arm bracket nut (M8x1.25), Nm (lb-ft) ................ 23.5-27.5 (17.4-20.3)
Fan drive pulley mounting nut (M30x1.5), Nm (lb-ft) ................ 137.3-156.9 (101.3-115.7)
Fan drive pulley screw (M16x1.5), Nm (lb-ft) ................ 313.8-333.4 (231.5-245.9)
Camshaft set screw (M8x1.25), Nm (lb-ft) ................ 23.5-27.5 (17.4-20.3)
Connecting rod screw (M8x1.0), Nm (lb-ft) ................ 44.1-49.0 (32.5-36.2)
Flywheel screw (M12x1.25), Nm (lb-ft) ................ 98.1-107.9 (72.3-79.6)
Bearing case cover screw (M8x1.25), Nm (lb-ft) ................ 23.5-27.5 (17.4-20.3)
Main bearing case screw 2 (M10x1.25), Nm (lb-ft) ................ 68.6-73.5 (50.6-54.2)
Main bearing case screw 1 (M9x1.25), Nm (lb-ft) ................ 46.1-51.0 (34.0-37.6)
Alternator’s pulley nut, Nm (lb-ft) ................ 58.3-78.9 (43.0-58.2)

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