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Kubota B2650, B2920 - Engine Service

B2650, B2920 tractors are equipped with a Kubota D1305 3-Cylinder Diesel Engine.

Kubota B2650, B2920 - Engine Separating

Hood, Side Cover and Battery Cord

Open the hood and remove the front grille. Disconnect the battery grounding cord. Disconnect the head light connectors and remove the hood and side covers.

Steering Wheel

Remove the steering wheel cap. Remove the steering wheel mounting nut and remove the steering wheel with a steering wheel puller. Steering wheel mounting - 29.4 to 49.0 Nm. Tightening torque nut - 3.0 to 5.0 kgfm.

Meter Panel and Panel Under Cover

Open the meter panel and disconnect the meter panel connector and hour-meter cable. Then remove the meter panel. Disconnect the combination switch connector, main switch connector and hazard switch connector. Tap out the spring pin and remove the hand accelerator lever. Remove the panel under cover.

Fuel Tank

Disconnect the fuel hose at the fuel filter side, then drain fuel completely. Remove the fuel tank frame stay. Disconnect the hazard unit, starter relay and regulator connectors and remove the lead wire for fuel gauge. Remove the fuse box. Disconnect the overflow hoses of fuel line. Remove the tank frame with fuel tank. Disconnect the hydraulic pipes and remove the battery stay with oil cooler. Disconnect the 2P connector and remove the engine stop solenoid.

Propeller Shaft Cover and Coupling

Loosen the clamp and slide the propeller shaft cover to the rear. Tap out the spring pin and then slide the coupling to the rear. Apply grease to the splines of the propeller shaft and coupling.

Universal Joint and Bearing Holder

Loosen the Clamp and slide the universal joint cover to the rear. Tap out the spring pins and then slide the universal joint to the rear. Remove the bearing holder with propeller shaft and universal joint. Apply grease to the splines of the propeller shaft and universal joint. When inserting the spring pins, face their splits in the direction parallel to the universal joint.

Drag Link

Remove the cotter pin and loosen the slotted nut. Disconnect the drag link with a pitman arm puller from the knuckle arm. Do not loosen the slotted nut to align the hole.

Separating the Kubota D1305 Engine from Clutch Housing

Disconnect the three point hitch delivery pipe and suction hose. Disconnect the glow plug lead wire and thermo sensor lead wire. And then disconnect the connector for dynamo and starter motor lead wire. Place the jack under the center frame. Hoist the engine by the chain at the engine hook. Remove the engine mounting screws and separate the engine from the clutch housing. Apply liquid gasket to joint face of the engine and clutch housing.

Separating Front Axle Assembly

Disconnect the radiator hoses. Remove the muffler pipe. Hoist the engine by the chain at the engine hook. Remove the front axle frame mounting screws and separate the front axle assembly from the engine. Clutch cover mounting - 23.5 to 27.5 Nm. Tightening torque screw - 2.4 to 2.8 kgfm.

Outer Parts

Remove the hydraulic pump. Remove the clutch assembly. Direct the shorter end of the clutch disc boss toward the flywheel. Apply molybdenum disulphide to the splines of clutch disc boss. Insert the pressure plate noting the position of straight pins. Be sure to align the center of disc and flywheel by inserting the clutch center tool. Do not allow grease and oil on the clutch disc facing.

Kubota B2650, B2920 - Engine Maintenance

Changing Engine Oil

Start and warm up the engine for approx. 5 minutes. Place an oil pan underneath the engine. To drain the used oil, remove the drain plug at the bottom of the engine and drain the oil completely. Screw in the drain plug. Fill new oil up to upper line on the dipstick. When using an oil of different manufacture or viscosity from the previous one, remove all of the old oil. Never mix two different types of oil.

Replacing Engine Oil Filter Cartridge

Remove the oil filter cartridge with the filter wrench. Apply a slight coat of oil onto the cartridge gasket. To install the new cartridge, screw it in by hand. Over tightening may cause deformation of rubber gasket. After the new cartridge has been replaced, the engine oil normally decrease a little. Thus see that the engine oil does not leak through the seal and be sure to read the oil level on the dipstick. Then, replenish the engine oil up to the specified level.

Kubota D1305 - Cleaning Air Cleaner Element

Remove the air cleaner cover and primary element. Clean the primary element if: When dry dust adheres to the element, blow compressed air from the inside turning the element. Pressure of compressed air must be under 686 kPa (7 kgf/cm2, 99 psi). When carbon or oil adheres to the element, soak the element in detergent for 15 minutes then wash it several times in water, rinse with clean water and dry it naturally. After element is fully dried, inspect inside of the element with a light and check if it is damaged or not. When replacing the air cleaner primary element, replace the secondary element as well: Once a year or after every six times of cleaning, whichever comes first.

Cleaning Fuel Filter

This job should not be done in the field, but in a clean place. Loosen and remove the fuel filter bowl, and rinse the inside with kerosene. Take out the filter element and dip it in the kerosene to rinse. After cleaning, reassemble the fuel filter, keeping out dust and dirt. Bleed the fuel system. When the fuel filter bowl has been removed, fuel stops flowing from the fuel tank. If the fuel tank is almost full, however, the fuel will flow back from the fuel return pipe to the fuel filter. Before the above checking, make sure the fuel tank is less than half-full.

Kubota B2650, B2920 Engine - Cylinder Head and Valves

Dynamo, Fan Belt and Muffler

Remove the dynamo and fan belt. Remove the cooling fan and fan pulley. Remove the air cleaner assembly and stay. Remove the muffler. Check to see that there are no cracks on the belt surface. After reassembling the fan belt, be sure to adjust the fan belt tension.

Cylinder Head Cover and Injection Pipes

Remove the head cover cap nuts. Remove the cylinder head cover. Loosen the screws on the pipe clamps. Detach the injection pipes. Check to see if the cylinder head cover gasket is not defective. Sent compressed air into the pipes to blowout dust. Then, reassemble the pipes in the reverse order.

Kubota B2650, B2920 - Nozzle Holder Assembly and Glow Plug

Remove the overflow pipe assembly. Remove the nozzle holder assemblies. Remove the copper gasket and heat seal. Remove the lead from the glow plugs. Remove the glow plugs. Replace the copper gasket and heat seal with new one.

Nozzle Heat Seal Service Removal Procedure

Use a plus (phillips head) screw driver that has a Dia. which is bigger than the heat seal hole (Approx. 6 mm) 1/4 in. Drive screw driver lightly into the heat seal hole. Turn screw driver three or four times each way. While turning the screw driver, slowly pull the heat seal out together with the copper gasket. If the heat seal drops, repeat the above procedure. Heat seal and copper gasket must be changed when the injection nozzle is removed for cleaning or for service.

Rocker Arm and Push Rod

Remove the rocker arm bracket nuts. Detach the rocker arm assembly. Remove the push rods. When putting the push rods onto the tappets, check to see if their ends are properly engaged with the grooves. After installing the rocker arm, be sure to adjust the valve clearance. Rocker arm bracket nut tightening torque - 21.6 to 26.5 Nm (15.9 to 19.5 ft-Ibs).

Kubota D1305 Cylinder Head

Loosen the pipe clamp, and remove the water return pipe. Remove the cylinder head screw in the order. Lift up the cylinder head to detach. Remove the cylinder head gasket and O-ring. Replace the cylinder head gasket with a new one. Securely fit the O-ring to the pipe pin. Tighten the cylinder head screws after applying sufficient oil. Tighten the cylinder head screws gradually screw in the order. Tighten them uniformly, or the head may deform in the long run. Retighten the cylinder head screws after running the engine for 30 minutes. Cylinder head screw tightening torque - 63.7 to 68.6 Nm (47.0 to 50.6 ft-Ibs).

Tappets

Remove the tappets from the crankcase. Visually check the contact between tappets and cams for proper rotation. If defect is found, replace tappets. Before installing the tappets, apply engine oil thinly around them. Do not change the combination of tappet and tappet guide.

Valves

Remove the valve caps. Remove the valve spring collet, pushing the valve spring retainer by valve spring replacer. Remove the valve spring retainer, valve spring and valve stem seal. Remove the valve. Wash the valve stem and valve guide hole, and apply engine oil sufficiently. After installing the valve spring collets, lightly tap the stem to assure proper fit with a plastic hammer.

Kubota B2650, B2920 - Timing Gears, Camshaft and Fuel Camshaft

Fan Drive Pulley

Set the stopper to the flywheel. Remove the fan drive pulley screw. Draw out the fan drive pulley with a puller. Fan drive pulley retaining tightening torque 235.4 to 245.2 Nm (173.6 to 180.8 ft-Ibs).

Fuel Pump, Hour Meter Gear Case and Water Pump

Remove the fuel pump. Remove the hour meter gear case. Remove the water pump flange. Before installing the hour meter gear case gasket, apply liquid gasket to the both side.

Gear Case

Remove the gear case. Remove the crankshaft collar and O-rings. Replace the gear case gasket with a new one. Be sure to set four O-rings inside the gear case and the O-ring on the crankshaft. Apply a thin film of engine oil to the oil seal, and install it, noting the lip come off. Length of the gear case mounting screws.

Speed Control Plate

Remove the speed control plate and governor lever from the governor springs 1 and 2. Securely catch the governor springs 1 and 2 on the governor lever. Apply a liquid gasket to both sides of the speed control plate gasket.

Injection Pump

Remove the injection pump mounting screws and nuts. Align the control rack pin with the notch on the crankcase, then remove the injection pump. Remove the injection pump timing shims. In principle, the injection pump should not be disassembled. Securely fit the control rack pin to the grooves of the fork lever and thrust lever. The sealant is applied to both sides of the shim (soft metal gasket shim). The liquid gasket is not required for assembling. Addition or reduction of shims (0.05 mm, 0.0020 in.) delays or advances the injection timing by approx. 0.0087 rad. (0.5°). In disassembling and replacing, be sure to use the same number of new shims with the same thickness.

Kubota B2650, B2920 - Fuel Camshaft

Remove the fuel camshaft stopper. Draw out the fuel camshaft and injection pump gear. Remove the fuel feed pump cam from the injection pump gear. Apply engine oil thinly to the fuel camshaft before installation. Check to see each aligning marks of cam and gear are aligned.

Governor Shaft

Remove the external snap ring from the governor shaft. Pull out the governor shaft. Make sure assembling the external snap ring of the governor shaft. Check the governor shaft for smooth rotation. When replacing the ball bearing of governor shaft, securely fit the ball bearing to the crankcase, apply an adhesive to the set screw, and fasten the screw until its tapered part contacts the circumferential end of the ball bearing.

Fork Lever

Remove the start spring. Remove the fork lever shaft cover. Pull out the fork lever shaft, and remove the spacer, bearing, fork levers 1 and 2. Apply a liquid gasket to the both sides of the fork lever shaft cover, and fit the fork lever shaft cover with the "UP" mark facing upwards. Securely fit the start spring.

Camshaft and Idle Gear 1

Remove the external snap ring, and then remove the idle gear 1. Remove the camshaft stopper mounting screw, and pull out the camshaft. When installing the idle gear 1, be sure to align the alignment marks on the gears. Securely fit the external snap ring and stopper.

Kubota B2650, B2920 - Piston and Connecting Rod

Oil Pan and Oil Strainer

Remove the oil pan mounting screws. Remove the oil pan by lightly tapping the rim of the pan with a wooden hammer. Remove the oil strainer. After cleaning the oil strainer, check to see that the filter mesh in clean, and install it. Visually check the O-ring, apply engine oil, and install it. Securely fit the O-ring to the oil strainer. Apply a liquid gasket to the oil pan. To avoid uneven tightening, tighten oil pan mounting screws in diagonal order from the center. Scrape off the old adhesive completely. Wipe the sealing surface clean using waste cloth soaked with gasoline. Now apply new adhesive 3 to 5 mm (0.12 to 0.20 in.) thick all over the contact surface. Apply the adhesive also on the center of the flange as well as on the inner wall of each bolt hole. Cut the nozzle of the "liquid gasket" container at its second notch. Apply "liquid gasket" about 5 mm (0.20 in.) thick. Within 20 minutes after the application of fluid sealant, reassemble the components. Wait then for about 30 minutes, and pour oil in the crankcase.

Connecting Rod Cap

Remove the connecting rod caps. Align the marks (a) with each other. (Face the marks toward the injection pump.). Apply engine oil to the connecting rod screws and lightly screw it in by hand, then tighten it to the specified torque. If the connecting rod screw won't be screwed in smoothly, clean the threads. If the connecting rod screw is still hard to screw in, replace it. Connecting rod screw tightening torque - 41.2 to 46.1 Nm (30.3 to 33.9 ft-Ibs).

Pistons

Turn the flywheel and bring the piston to top dead center. Draw out the piston upward by lightly tapping it from the bottom of the crankcase with the grip of a hammer. Draw out the other piston in the same method as above. Before inserting the piston into the cylinder, apply enough engine oil to the piston. When inserting the piston into the cylinder, face the mark on the connecting rod to the injection pump.

Piston Ring and Connecting Rod

Remove the piston rings using a piston ring tool. Remove the piston pin, and separate the connecting rod from the piston. When installing the ring, assemble the rings so that the manufacturer's mark near the gap faces the top of the piston. When installing the oil ring onto the piston, place the expander joint on the opposite side of the oil ring gap. Apply engine oil to the piston pin. When installing the connecting rod to the piston, immerse the piston in 80C oil for 10 to 15 minutes and insert the piston pin to the piston. When installing the connecting rod to the piston, align the mark on the connecting rod to the arrow's direction of casting mark on the piston. Mark the same number on the connecting rod and the piston so as not to change the combination.

Kubota B2650, B2920 - Engine Crankshaft

Flywheel

Fit the stopper to the flywheel. Remove the flywheel screws and then remove the flywheel. Fit the flywheel giving care to the position of the knock pin. Apply engine oil to the threads and the undercut surface of the flywheel bolt and fit the bolt. Flywheel screw tightening torque 53.9 to 58.8 Nm (39.8 to 43.4 ft-Ibs).

Bearing Case Cover

Remove the bearing case cover mounting screws. First, remove inside screws and then outside screws. Screw two removed screws into the screw hole of bearing case cover to remove it. Fit the bearing case gasket and the bearing case cover gasket with correct directions. Install the bearing case cover to position the casting mark "UP" on it upward. Apply engine oil to the oil seal lip and take care that it is not rolled when installing. Tighten the bearing case cover mounting screws with even force on the diagonal line.

Kubota D1305 - Crankshaft Assembly

Remove the main bearing case screw. Pull out the crankshaft assembly. Take care to protect crankshaft bearing from scratches caused by the crank gear, etc. (Wrap the gear in vinyl tape, etc.). Clean the oil passage of the crankshaft with compressed air. Apply oil to the main bearing case screw. Install the crankshaft assembly, aligning the screw hole of main bearing case with the screw hole of crankcase. Clean the oil passage of the crankshaft with compressed air. Main bearing case screw tightening torque - 49.0 to 53.9 Nm (36.2 to 39.8 ft-Ibs).

Main Bearing Case Assembly

Remove the two main bearing case screws 1, and remove the main bearing case assembly, being careful with the thrust bearing and crankshaft bearing 2. Remove the main bearing case assembly 1, 2 and 3 as above. Clean the oil passage in the main bearing case. Apply clean engine oil on the bearings. Install the main bearing case assemblies in the original positions. Since diameters of main bearing case vary, install them in order of makings from the gear case side. Match the alignment numbers on the main bearing case. When installing the main bearing case 1, 2, and 3, face the mark "FLYWHEEL" to the flywheel. Install the thrust bearing with its oil groove facing outward. Confirm that the main bearing case moves smoothly after tightening the main bearing case screw 1 to 29.4 to 34.3 Nm.