________________________________________________________________________________

Kubota L4701, L47, L6060 - Engine Components

Kubota V2403 4-cylinder diesel engine used in L4701, L47, L6060 tractors.

Kubota L4701, L47, L6060 - Fuel System

The common rail system is an electronically controlled fuel injection device, with a supply pump that pressurizes the fuel, a rail that stores the high-pressure fuel, injectors that inject the fuel under high-pressure based on solenoid operation into each cylinder and an engine ECU that controls all of these components. The injection amount and injection timing by the injectors and pressure of fuel stored in the rail are controlled by the engine ECU based on signals from each sensor and instructions sent by CAN communication from the main ECU on the tractor. Therefore, fuel is injected under optimal conditions at all times enabling suppressing of that which is a characteristic of Kubota V2403 diesel engines, generation of black smoke on start up and under acceleration achieving reduction in exhaust gas and higher output power.

Separator

The separator has a function of separating fuel and water through difference in specific gravity. There is a read float with a specific weight of 0.9 made of a polypropylene material inside that has properties in that it is heavier than diesel and lighter than water. When fuel containing water enters the separator, water with a high specific weight pools in the bottom of a cup and causes the float to float. The state of mixing in of water can be recognized by the state of the float and can be visually inspected externally. Fuel with a low specific weight flows over the top of the cup but passes through the element provided inside enabling filth to be removed from the fuel.

SCV

The suction control valve (SCV) is a proportional control valve that adjusts the amount of fuel delivered from the fuel pump to achieve the fuel pressure requested by the engine, has a function of delivering to the pressurizing part, and is made up of a piston, cylinder, armature, and solenoid etc. The SCV is a linear solenoid type electromagnetic valve and the engine ECU controls the time the solenoid is electrified (duty ratio control). When current flows through the solenoid, the armature moves based on the duty ratio and pushes on the cylinder and fuel flow changes based on position of the cylinder enabling suitable fuel flow. Since the suction control valve (SCV) has not been adopted as a part, replace the supply pump when SCV is needed to replace. Linear solenoid type: when voltage is applied to the coil, the moveable core moves linearly in proportion to the voltage based on the magnetic force.

Rail

The rail stores fuel at the high pressure applied by the supply pump and the injectors of each cylinder. The rail incorporates control parts-a rail pressure sensor and a pressure limiter. The pressure of the fuel in the rail is detected by the rail pressure sensor, and optimal feedback control is provided for the engine RPM and load. This greatly improves the ability to raise the pressure at low RPMs and enables high-pressure injection from low speed ranges. The pressure limiter operates when the pressure inside the rail becomes excessively high (valve opens), and then once the pressure drops to a certain pressure, it acts to keep the pressure (valve closes). Fuel discharged by the pressure limiter returns to the fuel tank.

Rail Pressure Sensor

The rail pressure sensor is mounted on the rail, detects the fuel pressure inside the rail, converts this to an electronic signal and sends it to the ECU. The rail pressure sensor is made up of a metal diaphragm, distortion detection part (metal gauge), signal processing circuit, and housing etc. When the fuel pressure in the rail is applied to the metal diaphragm, the diaphragm is distorted. Metal gauges are positioned in the center and at the edge of the metal diaphragm and tensile or compression force is applied. A difference in resistance values is generated based on the force that is applied.

Kubota L4701, L47, L6060 - Injectors

The injectors inject high-pressure fuel sent from the rail into the combustion chamber of Kubota V2403 engine. The injections are controlled by the signal of engine's ECU to produce the ideal timing, amount of fuel, mixture and spray. The injector injects a finely turned spray in three pulses during the combustion stage. First a small amount is injected, mitigating the effect of the initial burn and reducing NOx (oxides of nitrogen) and noise. The main injection follows with the real burn, and in the last stage, a diffuse combustion is induced, thus reducing particulate matter (PM) generated by the main injection.

Common Rail and Injection Pipes

Do not remove the pressure limiter and rail pressure sensor from the common rail. When removing the common rail, do not hold it by the pressure limiter and rail pressure sensor. Remove the injection pipes. Remove the overflow pipe. Remove the common rail. Store the injection pipes so it does not get any dust in it. Store the common rail so it does not get any dust in it.

Supply Pump

Remove the intake throttle valve assembly. Remove the EGR valve assembly. Remove the rail. Remove the intake manifold. Remove the supply pump. Do not disassemble the supply pump. Store the supply pump so it does not get any dust in it. When attaching the supply crank case, do not put force on the MPRP and overflow sections of the part. Do not remove the dust protection cap until immediately before you attach the part.

Replacing Fuel Filter

Remove the fuel filter. Put a film of clean fuel on rubber seal of new filter. Tighten the filter quickly until it contacts the mounting surface. Tighten filter by hand an additional 1/2 turn only. Bleed the fuel system.

Cleaning Water Separator

Close the fuel valve. Unscrew the retainer ring and remove the cup, and rinse the inside with kerosene. Take out the element and dip it in the kerosene to rinse. After cleaning, reassemble the water separator, keeping out dust and dirt. Bleed the fuel system.

Checking Fuel Line

Check to see that all line and hose clamp are tight and not damaged. If hoses and clamps are found worn or damaged, replace or repair them at once. If the fuel line is removed, be sure to properly bleed the fuel system.

Kubota L4701, L47, L6060 - Cooling System

Thermostat Assembly

Remove the thermostat cover mounting screws, and remove the thermostat cover. Remove the thermostat assembly. Replace the thermostat cover gasket with a new one. Apply a liquid gasket to the water flange 1 and flange 2.

Water Pump

Remove the water pump assembly from the gear case. Replace the gasket with a new one. Remove the pipe band and the water pipe (water pump side). Remove the water pump. When mounting the water pump, be careful not to forget mounting the O-ring and not to let it out of position.

Checking Coolant Level

Check to see that the coolant level is between the FULL and LOW marks of recovery tank. When the coolant level drops due to evaporation, add water only up to the full level. In case of leakage, add anti-freeze and water in the specified mixing ratio up to the full level. If the radiator cap has to be removed, follow the caution above and securely retighten the cap. Use clean, fresh water and anti-freeze to fill the recovery tank.

Adjusting Fan Belt Tension

Stop Kubota V2403 engine and remove the key. Apply moderate thumb pressure to belt between pulleys. If tension is incorrect, loosen the alternator mounting bolts and using a lever placed between the alternator and the engine block, pull the alternator out until the deflection of the belt falls within acceptable limits. Replace fan belt if it is damaged. Fan belt tension - Deflection of between 7 to 9 mm (0.28 to 0.34 in.) when the belt is pressed in the middle of the span.

Checking Radiator Hose and Hose Clamp

Check to see if radiator hoses are properly fixed every 200 hours of operation or six months, whichever comes first. If hose clamps are loose or water leaks, tighten bands securely. Replace hoses and tighten hose clamps securely, if radiator hoses are swollen, hardened or cracked. Replace hoses and hose clamps every 2 years or earlier if checked and found that hoses are swollen, hardened or cracked.

Flushing Cooling System and Changing Coolant

Stop the engine, remove the key and let it cool down. To drain the coolant, open the radiator drain plug and remove radiator cap. The radiator cap must be removed to completely drain the coolant. After all coolant is drained, reinstall the drain plug. Fill with clean soft water and cooling system cleaner. Follow directions of the cleaner instruction. After flushing, fill with clean soft water and anti-freeze until the coolant level is just below the radiator cap. Install the radiator cap securely. Fill with coolant up to the FULL mark of recovery tank. Start and operate the engine for few minutes. Stop the engine, remove the key and let cool. Check coolant level of recovery tank and add coolant if necessary. Properly dispose of used coolant.

Kubota L4701, L47, L6060 - Engine Control System

Engine ECU

The engine ECU controls the amount, timing, mixture and pressure of fuel that is injected. The engine ECU operates each kind of control based on the signals from each type of sensor. The actuator for controlling the amount, timing and mixture of fuel injection is the injector, while the actuator for controlling fuel pressure is the supply pump. Fuel Quantity Control - The amount of fuel to be injected is determined using a basic injection amount, which is calculated based on the state of the engine and driving conditions, with corrections added for parameters such as water temperature, intake air temperature, intake pressure, etc. Injection Timing Control - The ECU controls the timing for starting to energize the injectors, first determining the timing for the main injection and then setting the timing of other injections, such as pilot injections. Fuel Mixture Control - By conducting a pilot injection, the initial fuel mixture is kept to a minimum, mitigating the explosive initial combustion and reducing NOx and noise. Fuel Pressure Control - The ECU calculates the set fuel injection pressure based on the engine load (last injection amount and engine RPM) and controls the amount the supply pump supplies and the fuel pressure inside the rail.

Sensor

Crankshaft Position Sensor - The crank position sensor is mounted on the flywheel housing and the sensor body uses a hall element type. When pulse holes provided on the outer edge of the flywheel pass through the sensor, the internal magnetic field changes and this is output to the engine ECU. Also, a no hole part is provided in a part and this detects the crank position each rotation and outputs this to the engine ECU. The engine ECU uses the signals to calculate the crank angle and engine speed.

Camshaft Position Sensor - The cam position sensor is mounted near the supply pump gear of the gear case and the sensor functions in the same way as the crank position sensor. This sensor detects the teeth of the pulsar gear and the engine ECU uses this signal to calculate the cam angle.

Coolant Sensor - The temperature sensor is mounted to the water flange and uses a thermistor in the sensor part to detect temperature. A characteristic of thermistors is that their electrical resistance varies with temperature, and this characteristic is used by the different sensors to detect temperature via voltage.

Kubota L4701, L47, L6060 - DPF Regeneration System

Diesel Particulate Filter (DPF)

The Diesel Particulate Filter (DPF) is a device that captures and combusts PM in the exhaust gas. Physically captures the PM using a filter which spontaneously combusts when exhaust gas temperature is high. However, while exhaust gas temperature is low PM does not spontaneously combust the pressure differential between the inlet and outlet of the DPF is detected and the PM is combusted using a heat source generated using DOC to regenerate the filter. The Diesel Particulate Filter (DPF) is a filter to capture fine particles (soot and ash) contained in the exhaust gas of a Kubota V2403 diesel engine. The ash content is mainly metallic additives contained in burnt lubricating oil. The filter has a honeycomb structure with adjacent cell holes alternately closed. In addition, by alternately closing the inlet side and the outlet side of the exhaust gas, the thin ceramics wall is used as a filter. Fine particles in the exhaust gas are captured when they pass through this thin wall, and the exhaust gas is discharged as clean gas.

Intake Throttle Valve

The amount of air intake is regulated by the angle of the throttle valve and the exhaust temperature is controlled when regenerating the DPF muffler.

Air Flow Sensor

The amount of air intake required for control of the EGR valve used to reduce NOx is measured.

Temperature Sensor

This is mounted on the DPF muffler and the DPF muffler DOC intake, DPF intake, and DPF discharge exhaust temperature, needed for the post processing system, are measured.

Kubota L4701, L47, L6060 - Differential Pressure Sensor

The differential pressure sensor is a sensor that detects the pressure differential between the inlet and the outlet of the DPF. The engine ECU calculates the amount of accumulated PM in the DPF using this signal.

Oil Separator

Removes oil in the blow by gases that pass through the element and the oil is returned to the oil pan. Blow by gases that pass through the element are mixed into the intake upstream from the turbocharger.

Checking DPF Differential Pressure Sensor Pipes and Hoses

Be sure to loosen the differential pressure pipe tightening nut with crowfoot wrench to prevent the damage of the sensor or pipe. If it is still hard to loosen, apply the lubricant spray to threaded portion and soak it with lubricant. Tighten bolts and nuts to their specified torque. Also tighten the differential pressure pipe tightening nut to the specified torque with crowfoot wrench. Check the DPF differential pressure sensor pipe for crack, gas leakage and loose mounting nut. If you find a crack, change the DPF differential pressure sensor pipe. If you find a gas leakage, remove the DPF differential pressure sensor pipe and wipe off the anti-seize and lubricating compound. Apply the anti-seize and lubricating compound again, then tighten the DPF differential pressure sensor pipe to the specified torque. Check the DPF differential pressure sensor hose for crack, gas leakage. If you find a crack or gas leakage, change the DPF differential pressure sensor hose.

Kubota L4701, L47, L6060 - Electrical System

Starter Disassembling

Disassembling Motor - Disconnect the connecting lead from the magnet switch. Remove the screws, and then separate the end frame, yoke and armature. Remove the two screws, and then take out the brush holder from the end frame. Disassembling Magnet Switch - Remove the drive end frame mounting screws. Take out the overrunning clutch, ball, spring, gear, rollers and retainer. Apply grease to the gear teeth of the gear and overrunning clutch, and ball. Plunger - Remove the end cover. Take out the plunger.

Starter Service

Overrunning Clutch - Inspect the pinion for wear or damage. If there is any defect, replace the overrunning clutch assembly. Check that the pinion turns freely and smoothly in the overrunning direction and dose not slip in the cranking directions. If the pinion slips or dose not rotate in the both directions, replace the overrunning clutch assembly. Armature Bearing - Check the bearing for smooth rotation. If it dose not smooth rotation, replace it. Brush Wear - If the connect face of the brush is dirty or dusty, clean it with emery paper. Measure the brush length with vernier caliper. If the length is than the allowable limit, replace the yoke assembly and brush holder. Brush Holder - Check the continuity across the brush holder and the holder support with an ohmmeter. If it conducts, replace the brush holder. Field Coil - Check the continuity across the lead and brush with an ohmmeter. If it dose not conduct, replace the yoke assembly. Check the continuity across the brush and yoke with an ohmmeter. If it conducts, replace the yoke assembly.

Alternator Disassembling

Secure the hexagonal end of the pulley shaft with a double ended ratchet wrench, loosen the pulley nut with a socket wrench and remove it. Unscrew the three rear end cover screws and the B terminal nut, and remove the rear end cover. Unscrew the two screws holding the brush holder, and remove the brush holder. Unscrew the three screws holding the IC regulator, and remove the IC regulator. Remove the four screws holding the rectifier and the stator lead wires. Remove the rectifier. Unscrew the two nuts and two screws holding the drive end frame and the rear end frame. Remove the rear end frame. Press out the rotor from drive end frame. Unscrew the four screws holding the retainer plate, and remove the retainer plate. Press out the bearing from drive end frame with a press and jig. Lightly secure the rotor with a vise to prevent damage, and remove the bearing with a puller.

Alternator Service

Bearing - Check the bearing for smooth rotation. If it does not rotate smoothly, replace it. Stator - Check the continuity across each stator coil lead and core with an ohmmeter. If infinity is not indicated, replace it. Rotor - Measure the resistance across the slip rings with an ohmmeter. If the resistance is not the factory specification, replace it. Check the continuity across the slip ring and core with an ohmmeter. If infinity is not indicated, replace it. Slip Ring - Check the slip ring for score. If scored, correct with an emery paper or on a lathe. Measure the O.D. of slip ring with vernier calipers. If the measurement is less than the allowable limit, replace it. Slip ring O.D. - Allowable limit 14.0 mm (0.551 in). Brush Wear - Measure the brush length with vernier calipers. If the measurement is less than allowable limit, replace it. Make sure that the brush moves smoothly. If the brush is defective, replace it. Allowable limit 8.4 mm (0.331 in). Rectifier - Check the continuity across each diode of rectifier with an analog ohmmeter. Conduct the test in the (Rx1) setting. The rectifier is normal if the diode in the rectifier conducts in one direction and does not conduct in the reverse direction.

Separating DPF Muffler from Kubota L4701, L47, L6060 tractor

Front Grill, Skirts and Bonnet

Pull down the knob and open the bonnet. Disconnect the battery negative cable. Remove the front grill, left and right side skirts. Disconnect the head light connector. Remove the damper. Remove the pin, then the bonnet. When disconnecting the battery cables, disconnect the negative cable first. When connecting the battery cables, connect the positive cable first.

DPF Muffler

Remove the damper support. Disconnect the differential pressure connector and DPF temperature sensor connectors. Remove the muffler pipe mounting screws. Remove the DPF mounting screws R.H. Remove the exhaust flange mounting screws. Remove the DPF mounting screws L.H. Remove the DPF muffler using hoist. When mounting the DPF muffler to the bracket, make sure to follow the procedures below. Loosen the bracket mounting screws between the bracket and the exhaust flange. Loosen the bracket mounting screws until the bracket can move. Mount the DPF muffler to the bracket and temporarily tighten the screws. Tighten evenly and properly the exhaust flange mounting screws. Tighten evenly and properly the bracket mounting screws between the bracket and the exhaust flange. Tighten evenly and properly the bracket mounting screws. Tighten evenly and properly the DPF muffler mounting screws R.H and then the DPF muffler mounting screws L.H. Tighten evenly and properly the muffler pipe mounting screws.

Filter Comp (DPF)

Always work in the workshop equipped with a electric hoist (including mobile hoist). Put a tractor on a stable ground, and set the parking brake. As the DPF muffler is hot just after the engine shutdown, make sure to start operation after it gets cool. Make sure not to let any foreign substances enter the opening section during the operation. Make sure not to damage the DPF muffler full assembly by falling or impact as it contains a ceramic filter. Before removing the DPF for cleaning, keep the records of the engine serial number, DPF muffler full assembly part number, DPF muffler full assembly serial number, and engine operating time, which are required in preparing the DPF cleaning order from. Since the engine operating time is recorded in the ECU, check the operating time by connecting the service tool. When installing and removing the muffler full assembly (DPF), make sure that the temperature sensor, differential pressure sensor, and differential pressure pipe do not make contact with surrounding parts. Remove the hoses from the differential pressure pipes. Remove the differential pressure sensor. Remove the DPF mounting clamp band. Separate the Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), DPF outlet body respectively.