Specifications, Service and Repair of Farm and Lawn Tractors

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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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