Specifications, Service and Repair of Farm and Lawn Tractors

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Kubota L5040, L5740, MX5100, L4200 - Engine Service

Kubota L5040, L5740, MX5100 tractors fitted with V2403 diesel engine. V2203 engine used in L4200 model.

Kubota L4200, L5040, L5740, MX5100 - Fuel System

Cleaning the fuel filter pot

Every 100 hours of operation, clean the fuel filter in a clean place to prevent dust intrusion. Close the fuel filter lever. Remove the top cap, and rinse the inside with diesel fuel. Take out the element, and rinse it with diesel fuel. After cleaning, reinstall the fuel filter, keeping out of dust and dirt. Air-bleed the injection pump. Entrance of dust and dirt can cause a malfunction of the fuel injection pump and the injection nozzle. Wash the fuel filter cup periodically.

Fuel filter cartridge replacement

Replace the fuel filter cartridge with a new one every 400 operating hours. Apply fuel oil thinly over the gasket and tighten the cartridge into position by hand-tightening only. Finally, vent the air. Replace the fuel filter cartridge periodically to prevent wear of the fuel injection pump plunger or the injection nozzle, due to dirt in the fuel.

Air bleeding the fuel system

Air bleeding of the fuel system is required if: After the fuel filter and pipes have been detached and refitted; after the fuel tank has become empty; or before the engine is to be used after a long storage. Fill the fuel tank to the fullest extent. Open the fuel filter lever. Open the air vent cock on top of the fuel injection pump. Turn the engine, continue it for about 10 seconds, then stop it, or move the fuel feed pump lever by hand (optional). Close the air vent cock on top of the fuel injection pump. Always keep the air vent cock on the fuel injection pump closed except when air is vented, or it may cause the engine to stop. For fuel tanks that are lower than the injection pump. The fuel system must be pressurized by the fuel system electric fuel pump. If an electric fuel pump is not used, you must manually actuate the pump by lever to bleed. The primary fuel filter must be on the pressure side of the pump if the fuel tank is lower than the injection pump. To bleed, follow through above. Tighten air vent plug of the fuel injection pump except when bleeding, or it may stop the engine suddenly.

Checking the fuel pipes

Check the fuel pipes every 50 hours of operation. If the clamp band is loose, apply oil to the screw of the band, and tighten the band securely. If the fuel pipes, made of rubber, become worn out, replace them and clamp bands every 2 years. If the fuel pipes and clamp bands are found worn or damaged before 2 years pass, replace or repair them at once. After replacement of the pipes and bands, air-bleed the fuel system. When the fuel pipes are not installed, plug them at both ends with clean cloth or paper to prevent dirt from entering. Dirt in the pipes can cause fuel injection pump malfunction.

Air cleaner



Since the air cleaner employed on Kubota V2403 engine is a dry type, never apply oil to it. Open the evacuator valve once a week under ordinary conditions - or daily when used in a dusty place. This will get rid of large particles of dust and dirt. Wipe the inside air cleaner clean with cloth if it is dirty or wet. Avoid touching the element except when cleaning. When dry dust adheres to the element, blow compressed air from the inside turning the element. Pressure of compressed air must be under 205 kPa (2.1 kgf/cm2, 30 psi). Replace the element every year or every 6 cleanings. Make sure the wing bolt for the element is tight enough. If it is loose, dust and dirt may be sucked in, wearing down the cylinder liner and piston ring earlier and thereby resulting in poor power output. Do not over service the air cleaner element. Over servicing may cause dirt to enter the engine causing premature wear. Use the dust indicator as a guide on when to service. Evacuator valve - Open the evacuator valve once a week under ordinary conditions - or daily when used in a dusty place - to get rid of large particles of dust and dirt. For the air cleaner with a dust cup (optional) - Remove and clean out the dust cup before it becomes half full with dust; usually once a week, or even every day if the working surroundings are dusty. Install the air cleaner dust cup with "top" indicated on the rear of the cup in the up position. (However, it may be installed in either direction when the cover is placed at the lower part.). If the dust cup is mounted incorrectly, dust or dirt does not collect in the cup, and direct attachments of the dust to the element will cause its lifetime to shorten to a great extent.

Kubota L4200, L5040, L5740, MX5100 - Lubricating System

Checking oil level and adding engine oil

Check the engine oil level before starting or more than 5 minutes after stopping the engine. Remove the oil level gauge, wipe it clean and reinstall it. Take the oil level gauge out again, and check the oil level. If the oil level is too low, remove the oil filler plug, and add new oil to the prescribed level. After adding oil, wait more than 5 minutes and check the oil level again. It takes some time for the oil to drain down to the oil pan. Engine oil capacity - 7.5-9.5 L.

Changing engine oil

Change oil after the initial 50 hours of operation and every 200 hours thereafter. Remove the drain plug at the bottom of the engine, and drain all the old oil. Drain oil will drain easier when the oil is warm. Add new engine oil up to the upper limit of the oil level gauge.

Replacing the oil filter cartridge

Replace the oil filter cartridge. Apply a film of oil to the gasket for the new cartridge. Screw in the cartridge by hand. When the gasket contacts the seal surface, tighten the cartridge enough by hand. Because, if you tighten the cartridge with a wrench, it will be tightened too much. After the new cartridge has been replaced, the engine oil level normally decreases a little. Thus, run the engine for a while and check for oil leaks through the seal before checking the engine oil level. Add oil if necessary.

Kubota L4200, L5040, L5740, MX5100 - Cooling System

Radiator Cooling water

If the coolant temperature warning lamp lights up or if steam or coolant does not stop squirting from the radiator overflow pipe, turn off the load and keep the engine idling (Cooling-Down) for at least 5 minutes to let it cool down gradually. Then stop Kubota V2403 engine and take the following inspection and servicing. Check to see if the coolant runs short or if there is any coolant leak. Check to see if there is any obstacle around the cooling air inlet or outlet. Check to see if there is any dirt or dust between radiator fins and tube. Check to see if the fan belt is too loose. Check to see if radiator water pipe is clogged.

Checking coolant level, adding coolant

Remove the radiator cap, after the engine has completely cooled, and check to see that coolant reaches the supply port. If the radiator is provided with a recovery tank, check the coolant level of the recovery tank. When it is between the "Full" and "Low" marks, the coolant will last for one day's work. When the coolant level drops due to evaporation, add water only up to the full level. Check to see that two drain cocks; one is at the crankcase side and the other is at the lower part of the radiator. If the radiator cap has to be removed, follow the caution and securely retighten the cap. If coolant should be leak, repair it or replace. Make sure that muddy or sea water does not enter the radiator. Use clean, fresh water and 50% anti-freeze to fill the recovery tank. Do not refill recovery tank with coolant over the "Full" level mark. Be sure to close the radiator cap securely. If the cap is loose or improperly closed, coolant may leak out and decrease quickly.

Checking radiator hoses and clamp bands



Check to see if radiator hoses are properly fixed every 200 hours of operation or 6 months, whichever comes first. If hose clamps are loose or water leaks, tighten hose clamp 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. If the coolant temperature warning lamp lights up or if steam or coolant does not stop squirting from the radiator overflow pipe, turn off the load and keep the engine idling (Cooling-Down) for at least 5 minutes to let it cool down gradually. Then stop the engine and take the following inspection and servicing. Check to see if the coolant runs short or if there is any coolant leak. Check to see if there is any obstacle around the cooling air inlet or outlet. Check to see if there is any dirt or dust between radiator fins and tube. Check to see if the fan belt is too loose. Check to see if radiator water pipe is clogged.

Adjusting Fan Belt Tension

Stop the engine and remove the key. Apply moderate thumb pressure to belt between the 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. If belt is loosen or damaged and the fan is damaged, it could result in overheats or insufficient charging. Correct or replace belt.

Kubota L4200, L5040, L5740, MX5100 - Engine Components

Compression Pressure

After warming-up the engine, remove the air cleaner, muffler, glow lead, and glow plugs. Set a compression tester with the adaptor to the glow plug hole. Crank the engine with the starter to operate the engine approx. 200 to 300 min-1 (rpm). Measure a maximum value of the compression pressure. Do the same steps twice for each cylinder.

Cylinder Head Cover and Glow Plug

Remove the glow lead and the glow plugs. Remove the cylinder head cover. Check to see that the cylinder head cover gasket is not detective. Tighten the head cover mounting screws to specified torque. Replace the gasket of cylinder head cover with a new one. Adjust the direction of the ditch to the terminal side when the seal is installed in the glow plug. After installing the glow plug, make sure that the seal was set to the specified position.

Overflow Pipe and Injectors

Remove the overflow pipe. Remove the injector clamp. Remove the injector and its gasket. Do not disassemble the injector. Do not get the injectors out of order. If the injectors get out of order, it is necessary to perform injector correction. Store the injectors so they do not get any dust in them. Attach the O-ring to the correct position on the injector. After attaching gasket to the injector, attach the injector to the cylinder head. Correctly set the clamp. Attach the injector with screws. Check that the injector is attached securely. Do not remove the injector dust protection cap until immediately before you attach the injection pipe. To prevent the injector inlet connector from turning when removing the injection pipe cap nut, use a counter wrench. When the inlet connector becomes loose, replace the injector. If you replace the injectors, it is necessary to perform injector correction.

Rocker Arm and Push Rods

Remove the screws of the rocker arm bracket. Remove the rocker arm assembly. Remove the push rods. When you put the push rods on the tappets, make sure that their ends are correctly engaged with the grooves.

Kubota L4200, L5040, L5740, MX5100 - Cylinder Head

Remove the cylinder head screw. Lift up the cylinder head to remove. Remove the cylinder head gasket. Replace the cylinder head gasket with a new one. Apply sufficient oil and tighten the cylinder head screws. Tighten the cylinder head screws in a diagonal sequence. Start from the center in the sequence. Tighten them equally, or the shape of the head changes after some time.

Tappets

Remove the tappets from the crankcase. Before you install the tappets, apply a thin layer of engine oil around them. Examine the contact between tappets and cams that it turns correctly. If it is damaged, replace the tappets.

Valves

Remove the valve caps. Push the valve spring retainer with the valve spring replacer and remove the valve spring collets. Remove the valve spring retainer and valve spring. Remove the valve. Clean the valve stem and the valve guide hole, and apply engine oil sufficiently. After you install the valve spring collets, lightly tap the stem tip to attach it correctly with the plastic hammer.

Fan Drive Pulley

Lock the flywheel with the flywheel stopper. Remove the mounting nut of the fan drive pulley with a 46 mm (1.8 in.) deep socket wrench. Remove the fan drive pulley with a gear puller. Remove the feather key. Apply grease to the splines of coupling.

Gear Case

Remove the hour meter gear case (if attached). Remove the gear case. Remove the O-rings. Replace the gear case gasket and O-rings. Replace the hour meter gear case gasket with a new one. Make sure that there are 4 O-rings in the gear case. Apply a thin layer of engine oil to the oil seal. Then install the oil seal not to come off the lip. Before you install the gear case gasket, apply an adhesive that does not become dry.



Crankshaft Oil Slinger

Remove the crankshaft collar. Remove the O-ring. Remove the crankshaft oil slinger. Attach the crankshaft collar after you install the gear case to the cylinder body.

Idle Gear

Remove the external snap ring. Remove the idle gear collar. Remove the idle gear.

Camshaft and Balancer Shaft

Remove the camshaft set bolts and draw out the camshaft. Remove the balancer shaft 1 set bolts and draw out the balancer shaft 1. Remove the balancer shaft 2 set bolts and draw out the balancer shaft 2. When install the balancer shaft 1 and 2, be sure to place the 4th cylinders piston at the top dead center in compression then, align all mating marks on each gear to assemble the timing gears, set the idle gear last.

Kubota L4200, L5040, L5740, MX5100 - Fuel Camshaft

Remove the fuel feed pump. Remove the fuel camshaft stopper. Pull out the fuel camshaft assembly. After attaching the fuel camshaft, store oil in the pump room. Recommended oil amount about 110 cc.

Oil Pump

Remove the nut. Pull out the oil pump drive gear with a gear puller. Remove the 4 mounting screws of the oil pump. Remove the oil pump.

Oil Pan and Oil Strainer

Remove the oil pan mounting screws and remove the oil pan. Remove the oil strainer mounting screw, and remove the oil strainer. When installing the oil strainer, be careful not to damage the O-ring. Apply liquid gasket to the oil pan. Make sure that the liquid gasket coating surface is free of water, dust and oil in order to keep sealing effect. Carefully apply the adhesive evenly. Make sure the surfaces align when mounting parts with a liquid gasket applied to them. Mount parts with a liquid gasket within 10 minutes of application. Tighten the mounting screws of the oil pan in diagonal sequence from the center to tighten equally. After cleaning the oil strainer, install it. Attach the oil pan with its central drain plug facing toward the air suction side.

Pistons

Fully clean the carbon in the cylinders. Remove the connecting rod cap. Turn the flywheel and move the piston to top dead center. Lightly tap the piston from the bottom of the crankcase with the grip of a hammer to pull the piston out. Pull out the other piston in the same procedure as above. Before you install the piston into the cylinder, apply sufficient engine oil to the piston. When you install the piston into the cylinder, point the mark on the connecting rod to the fuel supply pump side. Do not change the combination of cylinder and piston. Align the position of each piston by its mark. For example, mark "1" on the No. 1 piston. Set the top ring with its gap (A) at 1.6 rad (90°) from the direction of the piston pin. Then set the second ring and the oil ring with their gaps (B), (C) at 2.09 rad (120°) from the top ring gap (A). Install the pistons with a piston ring compressor carefully. When you install the piston in position, do not give a damage to the layer of molybdenum disulfide on the piston skirt. This layer can decrease the clearance with the cylinder liner. Immediately after you press-fit the piston pin, the piston is hot and the layer comes off easily. Only put in the piston after its temperature decreases. When you replace the piston, look at the code number on top of the piston. Use a replacement piston with the same code number.

Piston Ring and Connecting Rod

Remove the piston rings with a piston ring tool. Remove the piston pin to disconnect the connecting rod from the piston. When you install the rings to the piston, set the manufacturer mark upward. When you install the oil ring on the piston, set the expander joint on the opposite side of the oil ring gap. When you install the piston pin, put the piston fully in 80C (176F) oil for 10 to 15 minutes. Apply engine oil to the piston pin. When you connect the piston and connecting rod, set the FW mark on the piston head to the flywheel side. When you install the piston into the cylinder, point the mark on the connecting rod to the fuel supply pump.

Kubota L4200, L5040, L5740, MX5100 - Flywheel

Attach the stopper to the flywheel. Remove 2 flywheel screws. Put the 2 flywheel guide screws in the holes. Remove all the flywheel screws. Remove the flywheel slowly along the flywheel guide screws. Do not use an impact wrench. Serious damage will occur. The flywheel is very heavy, so securely hold the flywheel when removing. Put in 2 flywheel guide screws. Check that there are no metal particles that remain on the flywheel mounting surfaces. Apply engine oil to the threads and the flange seat face of the flywheel screw. Then attach the screw.

Confirmation of Top Dead Center

Remove the rocker arm. Align the 4 piston with top dead center and remove the valve spring of the 4 cylinder. Insert an O-ring to prevent the exhaust valve from falling into the cylinder and position the dial gauge at the tip of the valve. While turning the flywheel to the left, the largest deflection of the needle on the gauge indicates top dead center so stop the flywheel in this position and set a tri-square as indicated in the diagram and place a top dead center mark on the reference line and flywheel on the engine body side. Note, in the case the flywheel is turned too far, return it by turning to the right and start over.

Confirmation of Crank Position Sensor Top Dead Center Detection Position

Align the reference (20th for 4 cylinder models) pulser hole from the area where there is no pulser hole on the outer circumference of the flywheel with the crank position sensor mounting hole on the flywheel housing. Insert a special tooling injection top correction jig into the crank position sensor mounting hole and align the center of handle and pulser. This position is the crank position sensor top dead center detection position so position the tri-square on the reference line set in the previous item and make a crank position sensor top dead center detection position mark on the flywheel.

Bearing Case Cover

Remove the mounting screws of the bearing case cover. First, remove inner screws and then external screws. Remove the bearing case cover. The length of inner screws and external screws are different. Make sure that you use the correct one at the correct position. Attach the bearing case gasket and the bearing case cover gasket in the correct directions. Put the casting mark UP of the bearing case cover upward, then install the bearing case cover. Apply a thin layer of engine oil to the oil seal. Then install the oil seal not to come off the lip. Tighten the mounting screws of the bearing case cover with an equal force on the diagonal line.

Crankshaft

Before you disassemble, measure the side clearance of crankshaft. Measure it when you assemble again. Remove the screw 2 of the main bearing case. Turn the crankshaft to set the crankpin of the third cylinder to the bottom dead center. Pull out the crankshaft until the crankpin of the second cylinder comes to the center of the third cylinder. Turn the crankshaft by 2.09 rad (120°) counterclockwise to set the crankpin of the second cylinder to the bottom dead center. Pull out the crankshaft until the crankpin of the first cylinder comes to the center of the third cylinder. Do the above steps again to pull out the crankshaft completely.

Main Bearing Case Assembly

Remove the screws 1 of the main bearing case. Then remove the main bearing case. Remove other main bearing cases as above. Clean the oil channel in the main bearing case. Apply clean engine oil on the bearings. Align the numbers on the main bearing case. When you install the main bearing case, point the mark FLYWHEEL to the flywheel. When you install the thrust bearing, point the oil groove externally. Install the main bearing case assemblies in the initial positions. Since the diameters of the main bearing cases are different, install them in the sequence of their marks (A, B for 3 cylinders and A, B, C for 4 cylinders) from the gear case side. After you tighten the screw 1 of the main bearing case to the specified torque, make sure that the main bearing case moves smoothly.

Kubota L4200, L5040, L5740, MX5100 - Engine Troubleshooting

Engine cranks slowly

Battery faulty or low charge - Charge or replace battery.
Faulty starter motor - Repair or replace starter motor.
Incorrect engine oil viscosity - Replace with proper engine oil.

Kubota V2203 engine will not crank

Discharged battery - Charge or replace battery.
Corroded battery terminals - Clean terminals.
Loose connection in starting circuit - Clean and tighten all connections.
Defective starting switch - Replace switch.
Starting motor brushes dirty - Clean or replace brushes.
Jammed starter drive gear - Loosen starter motor to free gear.
Faulty starter motor - Replace motor.
Seized engine - Inspect and repair.

Engine will not start

Empty fuel tank - Fill tank with proper fuel.
Dirty or plugged fuel filter - Clean fuel filters.
Air in injection lines - Bleed air in injection lines.
Faulty fuel feed pump - Repair fuel feed pump.
Faulty fuel injection pump - Repair fuel injection pump.
Faulty governor - Repair governor.
Misadjusted controls - Adjust speed and stop controls.
Improper fuel injection timing - Adjust fuel injection timing.
Poor valve seating - Check for broken or weak valve springs, warped stems, carbon and gum deposits and insufficient tappet clearance.
Damaged cylinder head gasket - Check for leaks around gasket when engine is cranked; if a leak is found, replace gasket.
Worn or broken piston rings - Replace worn or broken rings; check cylinders for out-of-round and taper.

Engine stops suddenly

Empty fuel tank - Fill fuel tank.
Air in fuel lines - Bleed fuel lines.
Governor malfunction - Repair governor.
Engine seized - Inspect and repair.

Engine slows unexpectedly

Overload - Locate cause for overload and rectify.
Fuel filter or fuel lines clogged - Inspect and unclog or replace.
Air in fuel system - Bleed air in fuel system.
Water in fuel - Remove water.
Misadjusted governor - Adjust governor.
Piston or bearing seizure - Repair damaged components; determine cause.

Engine will not run under full load

Clogged fuel filter - Clean fuel filter.
Faulty fuel feed pump - Repair fuel feed pump.
Worn fuel injection pump - Repair or replace fuel Injection pump.

Kubota V2203 engine knocks

Excessive bearing clearance - Inspect and repair.
Loose rod bolt - Inspect and repair.
Loose flywheel or coupling bolt - Tighten bolt.
Incorrect injection timing - Adjust timing.
Excessive fuel injected into cylinder - Inspect fuel injection pump and injectors.

Low oil pressure

Oil leaks - Inspect and repair.
Excessive bearing clearance - Inspect and repair.
Clogged oil filter element - Clean or replace filter element.
Faulty oil pressure regulator valve - Repair oil pressure regulator valve.
Low oil viscosity - Replace oil; check for dilution due to fuel leaking into crankcase.

Overheating

Dirty cooling system - Flush cooling system.
Faulty thermostat - Replace thermostat.
Insufficient coolant flow - Check water pump; check for blockage in system.
Insufficient coolant in closed system - Fill with proper coolant.
Air entering system - Check for loose clamps and damaged hoses.

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