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Kubota L3301, L3560, L3901 - Diesel Engine
Kubota D1803 3-cylinder diesel engine used in L3301, L3560, L3901
tractors.
Kubota L3301, L3560, L3901 - Cooling System
In addition to improving the cooling performance of the radiator by
utilizing a bottom bypass system, the mechanism uses a 3-stage
thermostat valve that reduces thermal shock considerably compared to
previous radiators. When the coolant inside a Kubota D1803 engine is
cool, the thermostat stays closed and coolant circulates inside the
engine via the bypass pipe. When the temperature of the coolant exceeds
the opening temperature of the thermostat, the thermostat opens in three
stages, sending the now hot coolant to the radiator. Further, when the
thermostat is fully open, it is structured so the hot coolant does not
flow into the engine via the bypass circuit, thus increasing the cooling
performance of the system.
Radiator Water Leakage
Fill a specified quantity of water into the radiator. Set a radiator
tester and an adaptor on the radiator. Increase the water pressure to
the specified pressure with the radiator tester and adaptor. Examine the
radiator for water leakage. For water leakages from the pinhole, replace
the radiator or repair with the radiator cement. When water leak is too
much, replace the radiator.
Opening-temperature of Thermostat Valve
Push down the thermostat valve and put the thread between the valve and
the valve seat. Put the thermostat and the thermometer in the container
and increase the temperature of the water gradually. Take the thread,
and float the thermostat in the water. As the water temperature rises,
the valve will open, and the thermostat will separate from the thread.
Measure the temperature at this moment. Continue to increase the
temperature and read the temperature when the valve opens approximately
8 mm (0.3 in.).
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.
Cleaning Grill, Radiator Screen and Oil Cooler
Before checking or cleaning the radiator screen, stop the engine and
wait long enough until it is cooled down. Check front grill and side
screens to be sure they are clean of debris. Detach the front skirt.
Detach the screen and remove all foreign materials. Grill and screen
must be clean from debris to prevent engine from overheating and to
allow good air intake for the air cleaner.
Kubota L3301, L3560, L3901 - Fuel System
Fuel cooler
The fuel cooler is set downstream of the separator and is used to cool
the fuel. When the pressure of fuel is increased, the temperature also
rises. The fuel in the common rail system is raised to high pressure so
the fuel temperature also rises. If the fuel temperature rises too much,
output and durability are reduced. A fuel cooler that suppresses fuel
temperature rise is provided to prevent this.
Feed pump
The feed pump is installed after the fuel cooler and has a function of
suctioning fuel from the fuel tank and pressure feeding it through a
filter and to the supply pump. Also, the feed pump is provided with a
priming pump. This is for air removal through the supply pump through
manual operation of the priming pump. Operating - During the up stroke,
the piston is pushed up by the fuel cam via the tappet and push rod. As
a result, the pressure in the inner chamber rises, the suction side
check valve closes and the discharge side check valve opens. On the
other hand, the pressure in the outer chamber is lowered so the suction
side check valve opens and discharge side check valve closes. During the
down stroke the piston is lowered by a piston spring and the pressure in
the inner chamber is lowered so the suction side check valve opens and
discharge side check valve closes. On the other hand, the pressure in
the outer chamber rises so the suction side check valve closes and
discharge side check valve opens.
Supply pump
The supply pump corresponds to conventional injection pumps but
pressurizes the fuel to more than 2 times that of conventional pumps for
delivery to the rail. The supply pump is made up of an intake adjustment
valve (SCV), pressurizing part, overflow valve, IO valve, and zero
delivery drain.
Cleaning Air Cleaner Primary Element
Remove the air cleaner cover and primary element. Clean the primary
element: 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). 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. Replace air cleaner primary element:
Once yearly or after every six times of cleaning, whichever comes first.
Cleaning Inner Air Filter (Cabin Type)
Press the inner air filter in the arrow-marked directions to unlock it
and remove the inner filter, and blow air from the direction opposite to
the filter's normal air flow. Pressure of compressed air must be under
205 kPa (2.1 kgf/cm2, 30 psi).
Kubota L3301, L3560, L3901 - 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.
Bleeding Fuel System
Air must be removed: When the fuel filter or lines are removed. When
water is drained from water separator. When tank is completely empty.
After the tractor has not been used for a long period of time. Fill the
fuel tank with fuel, and open the fuel valve. Loosen the air vent plug
on the fuel filter turns or so. Turn on the key switch and wait for
about 1 minute. Then tighten up the air vent plug. Set the hand throttle
lever at the minimum speed position and turn the key to START position.
If the engine does not start, try it several times at 30 second
intervals. Do not hold key switch at engine start position for more than
10 seconds continuously. If more engine cranking is needed, try again
after 30 seconds. Accelerate the engine to remove the small portion of
air left in the fuel system. If air still remains and the engine stops,
repeat the above steps.
Cleaning Fresh Air Filter (Cabin Type)
Remove the knob bolts and pull out the fresh air filter. Attach the
filter and cover. Normal use - Blow air from the opposite direction to
the filter's normal air flow. Pressure of compressed air must be under
205 kPa (2.1 kgf/cm2, 30 psi). If the filter is very dirty: Dip the
filter in lukewarm water with mild dish washing detergent. Move it up
and down as well as left and right to loosen dirt. Rinse the filter with
clean water and let it air-dry.
Kubota L3301, L3560, L3901 - EGR System
The EGR (Exhaust Gas Recirculation) system is a device that captures a
part of the exhaust gas and returns it to the intake side reducing the
amount of oxygen entering the engine and lowers combustion temperature
suppressing generation of nitrogen oxides (NOx). The EGR being used on
this engine is electronic and is made up of an EGR cooler, EGR lift
sensor, EGR valve motor, and reed valve. The exhaust gas that is
returned to the intake side (hereafter EGR gas) is cooled in the EGR
cooler, adjusted to a suitable flow by an EGR valve motor that is
controlled by the engine ECU, and is sent to the intake manifold. The
reed valve prevents reverse flow of air from the air cleaner to the EGR
valve motor.
EGR cooler
The EGR (Exhaust Gas Recirculation) cooler is used to lower combustion
temperature and efficiently cool EGR gas, with the aim of reducing the
NOx that is in the exhaust gas of Kubota D1803 diesel engine. The EGR
cooler is set between the cylinder head and the EGR valve and returns
the cooled exhaust gases to the engine suction side. The EGR cooler has
resistant to clogging up, compact and efficient tubes internally.
Reed valve
The reed valves are set at the point where exhaust gases that have
passed through the EGR valve mix with intake air and they prevent air on
the air cleaner side from flowing to the EGR cooler side. These thin
plate springs (reed valves) mounted at the bottom of the EGR valve motor
open and close the EGR gas passage (during intake: reed valve is closed;
during exhaust: open) and prevent the intake air from back flowing to
the exhaust side.
Kubota L3301, L3560, L3901 - EGR Valve
Water Cooled EGR Valve - This is a device that regulates EGR gas flow.
The degree the valve is open is detected using a lift sensor and a motor
is used to set this to the degree of open calculated using signals
including the engine speed. Also, passing engine coolant through the
housing enables controlling temperature rise of the EGR valve.
EGR Cooler (Exhaust gas passage)
Block the EGR cooler exhaust gas outlet. Attach an air hose to the EGR
cooler exhaust gas inlet and then submerge it in a water tank. Check
that the coolant passage is full of water. Apply the specified amount of
air pressure (290 kPa, 3.0 kgf/cm2, 43 psi) to the air hose side, and
check that there are no air leaks in any of the EGR cooler parts. If
there are air leaks, replace the EGR cooler. Block the EGR cooler
exhaust gas inlet, EGR cooler exhaust gas outlet, and the coolant
outlet. Attach an air hose to the EGR cooler coolant inlet, and then
submerge it in a water tank. Apply the specified amount of air pressure
(250 kPa, 2.5 kgf/cm2, 36 psi) to the air hose side, and check that
there are no air leaks in any of the EGR cooler parts. If there are air
leaks, replace the EGR cooler.
Checking and Cleaning EGR System
Perform an EGR actuation test. Based on test results, check that the EGR
valve gas passage and coolant passage are not clogged. Clean any soot
from the gas passage so that it does not damage the EGR valve. Clean the
coolant passage by running it with water.
Checking Exhaust Manifold
Examine the exhaust manifold for crack, exhaust gas leakage and loose
mounting screw. If you find a crack, change the exhaust manifold. If you
find a gas leakage, tighten the mounting screw again or replace the
gasket with a new one. If you find a loose mounting screw, tighten the
mounting screw again.
Kubota L3301, L3560, L3901 - Lubricating
System
Checking Engine Oil Level
Park the machine on a flat surface. Check engine oil before starting the
engine or 5 minutes or more after the engine has stopped. To check the
oil level, draw out the dipstick, wipe it clean, replace it, and draw it
out again. Check to see that the oil level lies between the two notches.
If the level is too low, add new oil to the prescribed level at the oil
inlet.
Changing Engine Oil
To drain the used oil, remove the drain plug at the bottom of the engine
and drain the oil completely into the oil pan. All the used oil can be
drained out easily when the engine is still warm. After draining
reinstall the drain plug. Fill with the new oil up to the upper notch on
the dipstick. Use DPF-compatible oil (CJ-4) for Kubota D1803 engine.
Replacing Engine Oil Filter
Remove the oil filter. Put a film of clean engine oil on the rubber seal
of the new filter. Tighten the filter quickly until it contacts the
mounting surface. Tighten filter by hand an additional 1/2 turn only.
After the new filter has been replaced, the engine oil normally
decreases a little. Make sure that the engine oil does not leak through
the seal and be sure to check the oil level on the dipstick. Then,
replenish the engine oil up to the prescribed level.
Lubricating Grease Fitting
Apply a small amount of multipurpose grease to the following points
every 50 hours. If you operated the machine in extremely wet and muddy
conditions, lubricate grease fittings more often. When apply a grease to
forward front axle support, remove the breather plug and apply a grease
until grease overflows from breather plug port. After greasing reinstall
the breather plug.
Replacing Oil Separator Element
Remove the cover and take out the element. Wipe off oil and the carbon
in the case with a clean rag. Fit a new oil separator element. Tighten
the cover.
Kubota L3301, L3560, L3901 - Electrical System
Starter
Motor Test - Disconnect the battery negative cable from the battery.
Disconnect the battery positive cable and the leads from the starter B
terminal. Remove the starter from the engine. Disconnect the connecting
lead from the starter C terminal. Connect a jumper lead from the
connecting lead to the battery positive terminal post. Connect a jumper
lead momentarily between the starter motor housing and the battery
negative terminal post. If the motor dose not run, check the motor.
Magnetic Switch Test - Disconnect the battery negative cable from the
battery. Disconnect the battery positive cable and the leads from the
starter B terminal. Remove the starter from the engine. Disconnect the
connecting lead from the starter C terminal. Connect a jumper lead from
the starter S terminal to the battery positive terminal post. Connect a
jumper lead momentarily between the starter C terminal and the battery
negative terminal post. If the pinion gear dose not pop out, check the
magnetic switch.
Glow Plug
Lead Terminal Voltage - Disconnect the wiring lead from the glow plug
after turning the main switch off. Turn the main switch key to the
PREHEAT position, and measure the voltage between the lead terminal and
the chassis. Turn the main switch key to the START position, and measure
the voltage with a voltmeter between the lead terminal and the chassis.
If the voltage at either position differs from the battery voltage, the
wiring harness or main switch is faulty. Glow Plug Continuity -
Disconnect the lead from the glow plugs. Measure the resistance with an
ohmmeter between the glow plug terminal and the engine body. If 0 ohm is
indicated, the screw at the tip of the glow plug and the housing are
short-circuited. If the factory specification is not indicated, the glow
plug is faulty.
Engine Stop Solenoid
Connector Voltage - Disconnect the 2P connector from engine stop
solenoid. Turn the main switch key to the ON position. Measure the
voltage with voltmeter between the terminal (Black / White), terminal
(White / Black) and Body. If the voltage differs from the battery
voltage, the wiring harness or main switch is faulty. Stop Solenoid Coil
- Disconnect the 2P connector from engine stop solenoid. Measure the
resistance with an ohmmeter between the terminal 1, terminal 2 and body.
If resistance differs from the factory specification, the coil is
faulty.
Kubota L3301, L3560, L3901 - Separating Clutch
Housing and engine
Steering Joint Shaft
Remove the steering joint screw. Remove the steering joint cover and the
steering joint support. Remove the steering joint shaft.
Fuel Tanks
Remove the left step. Remove the fuel hose cover. Remove the brake rod
L.H. Place the disassembling stands under the right and left fuel tanks.
Remove the front and rear support mounting screws of the right and left
fuel tanks. Lower the fuel tanks together with the disassembling stands.
Disconnect the fuel hoses, overflow hose and fuel level sensor connector
from the fuel tank L.H. Disconnect the fuel hose from the fuel tank R.H.
Wiring Harness
Remove the harness clamps and harness cover. Disconnect the battery
positive cable and battery. Remove the slow blow fuse box. Disconnect
the alternator terminal B and terminal IG. Disconnect the oil pressure
switch connector, starter terminal B and terminal ST. Disconnect the DPF
temperature sensor connectors and differential pressure connector.
Disconnect the injector connectors and glow plug connector. Disconnect
CCV GND wiring harness, CCV relay, CCV heater fuse, CCV SB fuse and CCV
heater.
Sensor Connectors
Disconnect the air flow sensor connector, intake throttle sensor
connector, electromagnetic pump connector and EGR valve connector.
Disconnect the common rail sensor connector, suction control valve
connector and camshaft position sensor connector. Disconnect the
crankshaft position sensor connector. Set aside the main harness to the
rear.
Steering and Panel Cover
Remove the steering wheel. Remove the mat. Remove the steering post
cover 2 and steering post cover 1. Remove the meter panel cover.
Propeller Shaft
Slide the propeller shaft cover after removing the screws. Tap out the
spring pins and slide the couplings and then remove the propeller shaft
with covers. Apply grease to the splines of propeller shaft.
Separating Kubota D1803 Engine from Clutch
Housing
Place the disassembling stands under the engine and clutch housing.
Remove the engine and clutch housing mounting screws and nuts. Separate
the engine and clutch housing. Apply grease to the spline of clutch
shaft. Apply liquid gasket to joint face of the flywheel housing and
clutch housing.
Radiator Assembly and DPF Muffler
Remove the air cleaner together with air cleaner hoses and bracket.
Remove the muffler pipe, muffler flange mounting screws and DPF muffler
together with DPF muffler bracket. Remove the oil separator. Disconnect
the radiator hoses. Disconnect the fuel cooler hoses. Remove the
radiator together with front support.
Fuel Hoses and Pillar
Disconnect the overflow hose and fuel hoses, then remove the bracket
together with fuel sub tank. Disconnect the overflow hose, fuel hose,
then remove the fuel filter. Disconnect the power steering return hose
and fuel hose. Remove the power steering delivery pipe. Remove the
dipstick stay. Remove the pillar.
Turbocharger
Disconnect the air intake hose. Remove the fan belt and alternator.
Remove the EGR cooler hose and cooler pipe. Disconnect the oil pipe and
return hose. Remove the exhaust manifold together with turbocharger. Be
sure to adjust the fan belt tension.
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