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Kubota B1700, BX2200, B8200 Engine - Check and Maintenance
Kubota D905 3-cylinder diesel engine used in B1700, BX2200, B8200
tractors.
Kubota B1700, BX2200, B8200 - Cooling System
Water Pump
The water pump is driven by the crankshaft via a V-belt. Water cooled in
the radiator is sucked into the water pump from its lower portion and is
sent from the center of the water pump impeller radially outward into
the water jacket in the crankcase. Remove the fan and fan pulley. Remove
the water pump from gear case cover. Remove the water pump flange. Press
out the water pump shaft with the impeller on it. Remove the impeller
from the water pump shaft. Remove the mechanical seal. Replace the
mechanical seal with new one.
Thermostat
The thermostat maintains the cooling water at correct temperature.
Kubota D905 engine uses a wax pellet type thermostat. Wax is enclosed in
the pellet. The wax is solid at low temperatures, but turns liquid at
high temperatures, expands and opens the valve. At low temperatures
(lower than 82C). As the thermostat is closed, cool ing water circulates
in the engine through the water return pipe without running to the
radiator. Air in the water jacket escapes to the radiator side through
leak hole of the thermostat. At high temperatures (higher than 82C).
When the temperature of cooling water exceeds 82C (180F), wax in the
pellet turns liquid and expands. Because the spindle is fixed, the
pellet is lowered, the valve is separated from the seat, and then
cooling water is sent to the radiator. Remove the thermostat cover.
Remove the thermostat. Apply a liquid gasket only at the thermostat
cover side of the gasket.
Checking Fan Belt Tension
Stop the engine and remove the key. Apply moderate thumb pressure to
belt between pulleys. If tension is incorrect, loosen the dynamo
mounting bolts (or alternator mounting bolts) and, using a lever placed
between the dynamo (or alternator) and the engine block, pull the dynamo
(or alternator) out until the deflection of the belt falls within
acceptable limits. Replace fan belt if it is damaged. Fan belt tension -
A 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.
Flush Cooling System and Changing Coolant
Stop the engine and let cool down. To drain the coolant, open the
radiator drain cock, and remove radiator cap. The radiator cap must be
removed to completely drain the coolant. After all coolant is drained,
close the drain plug. Fill with clean water and cooling system cleaner.
Follow directions of the cleaner instruction. After flushing, fill with
clean water and anti-freeze until the coolant level is just below the
port. Start and operate the engine for few minutes. Stop the engine.
Check coolant level and add coolant if necessary. Install the radiator
cap securely.
Kubota B1700, BX2200, B8200 - Fuel System
Fuel from the fuel tank passes through the fuel filter, and then enters
the injection pump after impurities such as dirt, water, etc. are
removed. The fuel pressurized by the injection pump to the opening
pressure (13.73 to 14.71 MPa, 140 to 150 kgf/cm2, 1991 to 2062 psi), of
the injection nozzle is injected into the combustion chamber. Part of
the fuel fed to the injection nozzle lubricates the moving parts of the
plunger inside the nozzle, then returns to the fuel tank through the
fuel overflow pipe from the upper part of the nozzle holder.
Fuel Filter
The fuel filter is installed between the fuel tank and fuel lift pump,
and serves to remove dirt and impurities from the fuel. Fuel from the
fuel tank enters the outside of the filter element and passes through
the filter element under its own pressure. As it passes through, the
dirt and impurities in the fuel are filtered out, allowing only clean
fuel to enter the interior of the filter element. The fuel exits from
the outlet of the cock body and is sent to the fuel lift pump. Cleaning
Fuel Filter - When operation period reaches approx. 100 hours, clean the
fuel filter. This job should not be done in the field, but in a clean
place so as to prevent dust from entering fuel system. Close the fuel
filter cock. Unscrew and remove the screw ring, and remove the filter
bowl, and rinse the inside with kerosene. Take out the element and dip
it in the kerosene to rinse. After cleaning reassembling the fuel
filter, keeping out dust and dirt. Bleed the fuel system. If dust and
dirt enter the fuel, the fuel pump and injection nozzle are subject to
wear. To prevent this, be sure to clean the fuel filter bowl
periodically.
Fuel Feed Pump
Filtered fuel is fed to the injection pump by the fuel lift pump. The
fuel lift pump operates as shown in the figure. Power is applied to the
tappet by an eccentric movement on the fuel camshaft. As the fuel
camshaft rotates, the eccentric movement causes the tappet to move up
and down. The tappet is linked to a flexible diaphragm via the pull rod.
When the diaphragm is pulled down, a low vacuum or low pressure area is
created above the diaphragm. This causes atmospheric pressure in the
fuel tank to force fuel into the fuel lift pump. The inlet valve opens
to admit fuel into the chamber. When the diaphragm is pushed up,
pressure is created in the area above the diaphragm. This pressure
closes the inlet valve and opens the outlet valve, forcing fuel from the
pump through the fuel pipe to the injection pump.
Governor
This mechanism maintains engine speed at a constant level even under
fluctuating loads, provides stable idling and regulates maximum engine
speed by controlling the fuel injection rate. Kubota D905 engine uses a
mechanical governor that controls the fuel injection rate at all speed
ranges (from idling to maximum speed) by utilizing the balance between
the flyweight's centrifugal force and spring tension. A governor shaft
for monitoring engine speed is independent of the injection pump shaft
and rotates at twice the speed of conventional types, providing better
response to load fluctuation and delivering greater engine output. At
start - As no centrifugal force is applied to flyweight, low tension of
start spring permits control rack to move to the starting position,
supplying the amount of fuel required to start the engine. At idling -
Setting speed control lever to the idling position during engine
rotation permits the low tension of governor spring, start spring and
idle limit spring to balance the centrifugal force of flyweight without
activating high tension governor spring. In this way, the fuel injection
rate can be controlled to ensure stable idling.
At high speed running with overload - Governor spring 1 and 2 control
the fuel injection rate. To maintain the required engine speed, fuel is
supplied according to the speed control lever setting and load by
balancing the tension of governor springs 1 and 2 with the centrifugal
force of flyweight. In addition, idle limit spring provides stable
engine rotation. During overload - At load increases, the engine speed
decreases, reducing the flyweight's centrifugal force. Governor springs
1 and 2, therefore, pull fork levers 1 and 2, increasing the fuel
injection rate and maintaining engine speed. If engine speed decreases
due to a further increase in load, fork lever 2 will come in contact
with the fuel limit bolt, stopping a further increase in the fuel
injection rate. Torque spring incorporated in fork lever 1 moves the
lever in the direction of fuel injection rate increase, thereby boosting
torque and providing greater engine output.
Checking Fuel Line
Stop the engine when attempting the check and change prescribed below.
Remember to check the fuel line periodically. The fuel line is subject
to wear and aging, fuel may leak out onto the running engine, causing a
fire. Check to see that all line and hose clamps are tight and not
damaged. If hoses and clamps are found worn or damaged, replace or
repair them at once. The fuel line is made of rubber and ages regardless
of period of service. Replace the fuel pipe together with the clamp
every two years and securely tighten. However if the fuel pipe and clamp
are found damaged or deteriorated earlier than two years, then change or
remedy. After the fuel line and clamp have been changed, bleed the fuel
system. When the fuel line is disconnected for change, close both ends
of the fuel line with a piece of clean cloth or paper to prevent dust
and dirt from entering. Entrance of dust and dirt causes malfunction of
the fuel injection pump. In addition, particular care must be taken not
to admit dust and dirt into the fuel pump.
Kubota B1700, BX2200, B8200 - Lubricating System
The lubricating system within this engine consists of an oil strainer,
oil pump, relief valve, oil filter cartridge and oil switch. The oil
pump draws in lubricating oil from the oil pan through the oil strainer.
The oil flows down to the filter cartridge, where it is further
filtered. Then the oil is force-fed to the crankshaft, connecting rods,
idle gear, camshaft and rocker arm shaft and lubricates each part. Some
part of oil, splashed by the crankshaft or leaking and dropping from
gaps of each part, lubricates these parts: pistons, cylinders, small
ends of connecting rods, tappets, push rods, inlet and exhaust valves.
Oil Filter Cartridge
Impurities in engine oil can cause to wear and seize components as well
as impairing the physical and chemical properties of the oil itself.
Impurities contained in force-fed engine oil are absorbed on the filter
paper for removal as they pass through the filter element. When the
filter element is clogged and the oil pressure in inlet line builds up
by 98 kPa (1.0 kgf/cm2, 14 psi) more than the outlet line, the bypass
valve opens and the oil flows from inlet to outlet bypassing the filter
element. Replacing Engine Oil Filter Cartridge - Be sure to stop a
Kubota D905 engine before changing 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. To prevent serious damage to the engine,
replacement element must be highly efficient.
Oil Pressure Switch
The oil pressure switch is mounted on the cylinder block, to warn the
operator that the lubricating oil pressure is poor. If the oil pressure
falls below 49kPa (0.5 kgf/cm 2,7 psi), the oil warning lamp will light
up, warning the operator. In this case, stop the engine immediately and
check the cause of pressure drop.
Engine Oil Pressure
Remove the oil switch and set a pressure tester. Start the engine. After
warming up, measure the oil pressure of both idling and rated speeds. If
the oil pressure is less than the allowable limit, check the following:
Engine oil insufficient, Oil pump defective, Oil strainer clogged, Oil
gallery clogged, Excessive oil clearance of bearing. Foreign matter in
the relief valve. At idle speed - More than 49 kPa (7 psi). At rated
speed - 196 to 441 kPa (36 to 64 psi).
Changing Engine Oil
Before changing oil, be sure to stop the engine. 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 bottom of the engine and
drain the oil completely. Screw in the drain plug. Fill new oil up to
upper notch on the dipstick. When using an oil of different manufacturer
or viscosity from the previous one, remove all of the old oil. Never mix
two different type of oil. Use the proper SAE Engine Oil according to
ambient temperatures. Engine oil capacity - 3 L.
Kubota B1700, BX2200, B8200 Engine - Basic Components
Cylinder Head
The cross-flow type intake/exhaust ports in this engine have their
openings at both sides of the cylinder head. Because overlaps of
intake/exhaust ports are smaller than in ports of other types which have
openings on one side, the suction air can be protected from being heated
and expanded by heated exhaust air. The cool, high density suction air
has high volume efficiency and raises the power of the engine.
Furthermore, distortion of the cylinder head by heated exhaust gas is
reduced because intake ports are arranged alternately. The combustion
chamber is exclusive E-TVCS combustion chamber type. Suction air is
whirled to be mixed effectively with fuel, prompting combustion and
reducing fuel consumption. In the combustion chamber are installed
throttle type injection nozzle and rapid heating sheathed type glow
plug. This glow plug assures easier than ever engine starts even at -15C
(5F).
Piston and Piston Rings
The piston has a slightly oval shape when cold (in consideration of
thermal expansion) and a concave head. Three rings are installed in
grooves in the piston. The top ring is a keystone type, which can stand
against heavy loads, and the barrel face on the ring fits well to the
cylinder wall. The second ring is an undercut type, which effectively
prevents the oil from being carried up. The oil ring has chamfered
contact faces and an expander ring, which increase the pressure of the
oil ring against the cylinder wall. Several grooves are cut on the top
land to help heat dissipate and to prevent scuffing.
Connecting Rod
Connecting rod is used to connect the piston with the crankshaft. The
big end of the connecting rod has a crank pin bearing (split type) and
the small end has a small end bushing (solid type).
Camshaft and Fuel Camshaft
The camshaft is made of special cast iron and the journal and cam
sections are chilled to resist wear. The journal sections are
force-lubricated. The fuel camshaft controls the reciprocating movement
of the injection pump. The fuel camshaft is made of carbon steel and the
cam sections are quenched and tempered to provide greater wear
resistance.
Inlet and Exhaust Valves
The inlet and exhaust valves and their guides are different from each
other. Other parts, such as valve springs, valve spring retainers, valve
spring collets, valve stem seals, and valve caps are the same for both
the inlet and exhaust valves. All contact or sliding parts are quenched
and tempered to resist wear.
Valve Timing
The valve opening and closing timing is extremely important for
effectively intaking air into the cylinder and sufficiently exhaust gas.
An appropriate timing can be obtained by aligning the alignment marks on
the crank gear and cam gear. Inlet valve open - 0.24 rad. (14°) before
T.D.C. Inlet valve close - 0.52 rad. (30°) after B.D.C. Exhaust valve
open - 0.96 rad. (55°) before B.D.C. Exhaust valve close - 0.24 rad.
(14°) after T.D.C.
Kubota B1700, BX2200, B8200 - Cylinder Head and Valve
Remove the dynamo (or alternator) and fan belt. Remove the cooling fan
and fan pulley. Check to see that there are no cracks on the belt
surface. Remove the head cover. Check to see if the head cover gasket is
not defective. Loosen the screws on the pipe clamps. Detach the
injection pipes. Send compressed air into the pipes to blowout dust.
Then, reassemble the pipes in the reverse order. Remove the overflow
pipe assembly. Detach the nozzle holders using a 21 mm deep socket
wrench. Remove the copper gasket and heat seal. Remove the glow plug
cock and glow plugs. Remove the set nuts for the rocker arm brackets.
Detach the whole rocker arm. Remove the push rods. Remove the external
snap ring, and detach the rocker arm, spring and rocker arm bracket from
the rocker arm shaft. Before detaching the rocker arm bracket of gear
case side from the rocker arm shaft, be sure to remove the set screws.
Before inserting the push rods into the tappets, check to see if their
ends are properly engaged with the grooves. Remove the push rods.
When putting the push rods onto the tappets, check to see if their ends
are properly engaged with the grooves. Remove the cylinder head. Reverse
the fastening procedure to loosen the head bolts. Remove the head
gasket. Completely remove gaskets left in the cylinder head and crank
case. Replace the head gasket by a new one and fit it with the grommets
for the combustion chambers on the side of the cylinder heads. Tighten
the cylinder head screws after applying sufficient oil. Tighten the
cylinder head screws in diagonal sequence starting from the center.
Tighten them uniformly, or the head may deform in the long run. Remove
the O-ring from the periphery of the oil pipe on the crankcase. Remove
the six tappets from the crankcase. 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.
Timing Gears and Camshaft
Set the stopper to the flywheel. Remove the screw and detach the fan
drive pulley. Check to see the fan drive pulley is aligned with its
aligning mark. Remove the fuel pump. Remove the hour meter gear case.
Before installing the hour meter gear case gasket, apply liquid gasket
to the both side. Remove the water pump flange. Before installing the
water pump flange gasket, apply liquid gasket to the both side. Remove
the gear case. Remove the crankshaft collar and O-rings. 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 comes off. Remove the engine stop solenoid. Apply a thin coat of
liquid-type gasket to both surfaces of the solenoid's cover packing.
Confirm the convex part of the flange of the engine stop solenoid has
fit into the hole, and then fasten the bolts.
Remove the speed-regulating plate, and governor lever from the governor springs 1 and 2. Securely catch governor springs 1 and 2 on the governor lever. Apply a thin coat of liquid-type gasket to both surfaces of the packing of the speed regulating plate. Set the control rack pin to the notch of the pump fitting surface of the crank case to remove the injection pump. Remove the shims for adjusting injection timing. At this time confirm the number of shims removed. Remove the stopper and then the fuel camshaft. Securely fix the fuel camshaft with the stopper. Remove the fuel feed pump cam from the injection pump gear. Check to see each aligning mark is aligned. Remove the hydraulic pump. Remove the external snap ring from the governor shaft. Pull out the governor shaft. Securely fit the external snap ring of the governor shaft and idle gear shaft. Confirm the governor shaft rotates smoothly. Remove the start spring. Remove fork lever shaft cover.
Pull out the fork lever shaft, and remove the spacer, bearing, fork
levers 1 and 2, etc. Be careful in handling the thrust lever since the
sintered part will be broken if it's dropped on the floor (or the
ground). Apply a thin coat of liquid-type gasket to both surfaces of the
packing of the fork lever shaft cover, and fit the fork lever shaft
cover with the UP mark facing upwards. Securely fit the start spring.
Remove the external snap ring and then remove the idle gear 1. Remove
the stopper bolt and pull out the camshaft. Fit them with the marks of
each gear set to each other. Fit the camshaft. Fit idle gear 1 with its
mark set to the marks of the crank gear and cam gear. Fit the injection
pump gear with its mark set to the mark of idle gear 1. Fit the
injection pump gear and governor shaft. Securely fit the external snap
ring and the stopper.
Connecting Rod and Piston
Remove the oil pan. Remove the oil strainer. After cleaning the oil
strainer, check to see that the filter mesh is 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 liquid-type gasket to the oil
pan side of the oil pan packing. Remove the connecti ng rod bolt and the
connecti ng rod cap. Rotate the flywheel to position the piston at the
top dead center, and then push out the piston and connecting rod to the
side of the cylinder head with a hammer's grip, etc. Put a number tag to
the pistons and connecting rods for their right combinations with the
cylinders. Apply engine oil to the crank pin bearing and the cylinder.
Apply engine oil to the crank pin bearing, and fit it with the marks of
the connecting rod and the connecting rod cap set to each other.
Apply engine oil to the connecting rod bolt and lightly screw it in by
hand, then fasten it up with a prescribed torque. If the bolt won't be
screwed in smoothly, clean the threads. If the bolt is still hard to
screw in, replace it. Remove the piston ring with a piston ring tool.
Pull out the piston pin and remove the connecting rod. Properly arrange
the pistons and the connecting rods for their right combinations. Fit
the piston to the connecting rod with mark 1 on the piston head set
opposite to the mark of the connecting rod. When driving in the piston
pin; clean the small end bushing, piston pin and piston pin hole, warm
the piston to 80-100C, and apply oil to the pin. Securely fit the
internal snap ring to the groove of the piston. Fit the oil ring with
the expander gap set opposite to the ring gap. Fit the piston ring with
its gap at 45° from the piston pin's direction. Fit the piston rings
with their marks facing upwards.
Crankshaft
Fit the stopper to the flywheel. Remove the flywheel bolt and then 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. Remove the bolts fixing the main bearing case
cover. First, remove inner bolts and then outer bolts. Screw the newly
removed bolts into the outer bolt holes on the main bearing case cover
to remove the cover. Fit the cover giving care to the directions of the
bearing case packing and the bearing case cover packing. Check the oil
seal lip of the main bearing case cover for any scratches or dents, and
if none of them are found, apply engine oil to the lip and fit the cover
with the lip kept attached. Fit the main bearing case cover with the
"UP" mark facing upwards. Remove bearing case bolt 2.
Remove the crankshaft together with the main bearing case. Take care to protect crankshaft bearing 1 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. Set the bolt holes of the crank case to those of the main bearing case. Apply engine oil to the threads of bearing case bolt 2, and fit the crankshaft. Fit the main bearing case wheel with the "Up" mark facing upwards. Clean the main bearing case, apply oil, and fit it to the crank case. Remove bearing case bolt 1, and the main bearing case from the crankshaft. Properly arrange the main bearing cases and the bearings for their right combinations. Apply engine oil to the bearings and fit the case. Fit the main bearing case with the FLYWHEEL mark set on the side of the flywheel. Fit the main bearing case wheel with the bolt holes set on the side of the flywheel and the side metals with the oil groove facing outside.
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