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Kubota B3030, B3350, B3150, B7800 - Engine Maintenance

B3030, B3350, B3150, B7800 tractors are equipped with a Kubota V1505 4-cylinder diesel engine.

Kubota B3030, B3350, B3150, B7800 - Separating Engine

Bonnet, Front Grille, Side Covers and ROPS

Open the bonnet. Remove the pin and the plain washer. Remove the wiring harness from the bonnet. Remove the hood. Remove the front grille and the side covers. Remove the ROPS. Install the bush to the bonnet securely. Install the hood. Don't damage the bonnet when installing it.

Battery

Disconnect the battery negative cable first. Disconnect the battery positive cable second. Remove the battery. Remove the front hitch.

Hydraulic Hoses from Power Steering Cylinder

Disconnect the hydraulic hoses from the power steering cylinder. Removing the snap pin and disconnect the bi-speed rod.

Steering Wheel, Meter Panel, Shuttle Lever and Panel Lower Cover

Remove the steering wheel cap. Remove the steering wheel mounting nut. Remove the steering wheel with a steering wheel puller. Remove the accelerator lever grip and the steering boot. Disconnect the hour meter cable and wiring harness connectors. Remove the meter panel not to damage with the steering shaft. Remove the shuttle lever. Remove the panel lower cover. Tighten the steering wheel mounting nut securely.

Fuel Tank

Disconnect the leads from the fuel tank. Disconnect the overflow hoses from the fuel tank. Remove the shutter plate and the fuel tank.

Key Stop Solenoid and Hydraulic Delivery Pipe

Remove the key stop solenoid connector. Remove the engine stop solenoid using a small size ratchet handle, the extension joint, the universal joint and the thinner socket (10 mm). Remove the hydraulic delivery pipe mounting nuts. Slide the hydraulic delivery pipe. Loosen the hose band. Disconnect the suction hose from the hydraulic pump. Apply the liquid gasket to the joint face of the key stop solenoid and the engine.

Final Separating Engine

Reinstall the rear tires. Support the transmission with a disassembling stand. Hook the engine with a hoist. Place the disassembling stand under the main frame. Disconnect the power steering hoses. Loose the hydraulic inlet hose band. Disconnect the hydraulic inlet hose from the hydraulic pump. Disconnect the hydraulic delivery pipe from the hydraulic pump. Disconnect the wiring leads from the alternator, the engine oil pressure switch and the starter motor. Disconnect the wiring harness and the power steering hoses from the engine body. Remove the docking bolts between the engine and the front case. Align the spline between the front wheel drive shaft and the universal joint securely. Tighten the docking bolts between the engine and the front case securely. Remove the exhaust pipe. Disconnect the radiator hoses. Remove the front axle frame mounting bolts. Separate the front axle from the engine.

Kubota B3030, B3350, B3150, B7800 - Engine Components

Compression Pressure

Run the engine until it is warmed up. Stop the engine and disconnect the 2P connector from the engine stop solenoid. Remove the air cleaner, the muffler and all injection nozzles. Set a compression tester with the adaptor to the nozzle hole. While cranking the engine with the starter, measure the compression pressure. Repeat steps 4 through 6 for each cylinder. If the measurement is below the allowable limit, apply a small amount of oil to the cylinder wall through the nozzle hole and measure the compression pressure again. If the compression pressure is still less than the allowable limit, check the top clearance, valve and cylinder head. If the compression pressure increases after applying oil, check the cylinder wall and piston rings. Check the compression pressure with the specified valve clearance. Always use a fully charged battery for performing this test. Variances in cylinder compression values should be under 10 0/0. Compression pressure - 2.84 to 3.24 MPa (412 to 469 psi). Allowable limit - 2.26 MPa (327 psi).

Top Clearance

Remove the cylinder head. (Do not attempt to remove the cylinder head gasket.). Move the piston up, and stick a strip of fuse (1.5 mm dia./ 0.059 in. dia.), 5 to 7 mm long / 0.197 to 0.276 in. long) on the piston head at three positions with grease so as to avoid the intake and exhaust valves and the combustion chamber ports. Lower the piston, and install the cylinder head and tighten the cylinder head screws to the specified torque. Turn the crankshaft until the piston exceeds its top dead center. Remove the cylinder head, and measure the thickness of the squeezed fuses. If the measurement is not within the factory specifications, check the oil clearance between the crankpin and crankpin bearing and between the piston pin and small end bushing. After checking the top clearance, be sure to assemble the cylinder head with a new cylinder head gasket. Top clearance - 0.55 to 0.70 mm (0.0217 to 0.0276 in).

Valve Clearance

Valve clearance must be checked and adjusted when engine is cold. Remove the head cover, the glow plugs and the timing window cover on the clutch housing. Align the "1TC" mark line on the flywheel and center of timing window so that the No. 1 piston comes to the compression or overlap top dead center. Check the following valve clearance marked using a feeler gauge. If the clearance is not within the factory specifications, adjust with the adjusting screw. Valve Clearance - 0.145 to 0.185 mm (0.0057 to 0.0073 in).

Kubota V1505 - Timing Gear

Set a dial indicator (lever type) with its tip on the gear tooth. Move the gear to measure the backlash, holding its mating gear. If the backlash exceeds the allowable limit, check the oil clearance of the shafts and the gear. If the oil clearance is proper, replace the gear.

Backlash between idle gear 1 and crank gear 0.032 to 0.115 mm / 0.00120 to 0.00453 in.
Backlash between idle gear 1 and cam gear 0.036 to 0.114 mm / 0.00142 to 0.00449 in.
Backlash between idle gear 1 and injection pump gear 0.034 to 0.116 mm / 0.00134 to 0.00457 in.
Backlash between idle gear 1 and idle gear 2 0.033 to 0.117 mm / 0.0013 to 0.0046 in.
Backlash between idle gear 2 and governor gear 0.030 to 0.117 mm / 0.00118 to 0.00461 in.

Idle Gear Side Clearance - Set a dial indicator with its tip on the idle gear. Measure the side clearance by moving the idle gear to the front and rear. If the measurement exceeds the allowable limit, replace the idle gear collar. Idle gear side clearance - 0.050 to 0.150 mm (0.0020 to 0.0059 in). Idle Gear 2 Side Clearance - Set a dial indicator with its tip on the idle gear. Measure the side clearance by moving the idle gear to the front and rear. If the measurement exceeds the allowable limit, replace the idle gear collar. Idle gear 2 side clearance - 0.20 to 0.51 mm (0.0079 to 0.0201 in).

Cylinder Wear

Measure the I.D. of the cylinder at the six positions with a cylinder gauge to find the maximum and minimum I.D.'s. Get the difference (Maximum wear) between the maximum and the minimum I.D.'s. If the wear exceeds the allowable limit, bore and hone to the oversize dimension. Visually check the cylinder wall for scratches. If deep scratches are found, the cylinder should be bored. Cylinder liner I.D. - 78.000 to 78.019 mm / 3.01086 to 3.07161 in.

Kubota B3030, B3350, B3150, B7800 - Lubricating System

Changing Engine Oil

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 the bottom of the engine and drain the oil completely. Screw in the drain plug. Fill new oil up to upper line on the dipstick. When using an oil of different manufacture or viscosity from the previous one, remove all of the old oil. Never mix two different types of oil.

Replacing Engine 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.

Engine Oil Pressure

Remove the engine oil pressure switch, and set a oil pressure tester. Start the engine. After warming up, measure the oil pressure of both idling and rated speeds.

Oil Pump

Rotor Lobe Clearance - Measure the clearance between lobes of the inner rotor and the outer rotor with a feeler gauge. If the clearance exceeds the factory specifications, replace the oil pump rotor assembly. Clearance between Outer Rotor and Pump Body - Measure the clearance between the outer rotor and the pump body with a feeler gauge. If the clearance exceeds the factory specifications, replace the oil pump rotor assembly. Clearance between Rotor and Cover - Put a strip of plastigage onto the rotor face with grease. Install the cover and tighten the screws. Remove the cover carefully, and measure the amount of the flattening with the scale and get the clearance. If the clearance exceeds the factory specifications, replace oil pump rotor assembly.

Kubota B3030, B3350, B3150, B7800 - Cooling System

Fan Belt

Fan Belt Tension - Measure the deflection, depressing the belt halfway between the fan drive pulley and alternator pulley at specified force (98 N, 10 kgf, 22 Ibs). If the measurement is not within the factory specifications, loosen the alternator mounting screws and relocate the alternator to adjust. Deflection - 7 to 9 mm / 0.28 to 0.35 in. Fan Belt Damage and Wear - Check the fan belt for damage. If the fan belt is damaged, replace it. Check if the fan belt is worn and sunk in the pulley groove. If the fan belt is nearly worn out and deeply sunk in the pulley groove, replace it.

Radiator

Radiator Water Leakage - Pour a specified amount of water into the radiator. Set a radiator tester and raise the water pressure to the specified pressure. Check the radiator for water leaks. For water leak from the pinhole, replace the radiator or repair with the radiator cement. When water leak is excessive, replace the radiator. Radiator Cap Air Leakage - Set a radiator tester on the radiator cap. Apply the specified pressure (88 kPa, 0.9 kgf/cm2, 13 psi), and measure the time for the pressure to fall to 59 kPa (0.6 kgf/cm2, 9 psi). If the measurement is less than the factory specification, replace the radiator cap. 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.

Thermostat Assembly

Remove the thermostat cover mounting screws, and remove the thermostat cover. Remove the thermostat assembly. Apply a liquid gasket only at the thermostat cover side of the gasket.

Water Pump Assembly

Loosen the alternator mounting bolts, and remove the fan belt. Remove the fan and fan pulley. Remove the water pump assembly from the 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. Apply a liquid gasket to the both sides of gasket. Replace the mechanical seal with new one.

Kubota B3030, B3350, B3150, B7800 - Fuel System

Cleaning Air Cleaner Element

Remove the air cleaner cover and primary element. Clean the primary element if: When dry dust adheres to the element, blow compressed air from the inside turning the element. Pressure of compressed air must be under 686 kPa (7 kgf/cm2, 99 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. When replacing the air cleaner primary element, replace the secondary element as well: Once a year or after every six times of cleaning, whichever comes first.

Cleaning Fuel Filter

This job should not be done in the field, but in a clean place. Loosen and remove the fuel filter bowl, and rinse the inside with kerosene. Take out the filter element and dip it in the kerosene to rinse. After cleaning, reassemble the fuel filter, keeping out dust and dirt. Bleed the fuel system. When the fuel filter bowl has been removed, fuel stops flowing from the fuel tank. If the fuel tank is almost full, however, the fuel will flow back from the fuel return pipe to the fuel filter. Before the above checking, make sure the fuel tank is less than half-full.

Checking Fuel Line

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.

Checking Intake Air Line

Check to see that hoses and hose clamps are tight and not damaged. If hoses and clamps are found worn or damaged, replace or repair them at once.

Kubota V1505 - Bleeding Fuel System

Air must removed: When the fuel filter or lines are removed. When tank is completely empty. After the tractor has not been used for a long period of time. Bleeding procedure is as follows: Fill the fuel tank with fuel. Start the engine and run for about 30 seconds, and then stop the engine.

Injection Timing

Remove the injection pipes. Remove the engine stop solenoid, push in the control rack of the injection pump by 5 mm (0.2 in.) and hold it at that position. Turn the flywheel counterclockwise (facing the flywheel) until fuel flows from the delivery valve holder. Continue to turn the flywheel slowly, and stop it as soon as the fuel level at the tip of the delivery valve holder begins to increase. Check to see if the timing angle lines on the flywheel is aligned with the alignment mark. If the injection timing is out of adjustment, readjust the timing with shims.

Fuel Tightness of Pump Element

Remove the engine stop solenoid. Remove the injection pipes and glow plugs. Install the injection pump pressure tester to the injection pump. Set the speed control lever to the maximum speed position. Turn the flywheel ten times or more to increase the pressure. If the pressure can not reach the allowable limit, replace the pump element or injection pump assembly. Fuel tightness of pump element - 14.7 MPa (2133 psi).

Fuel Valve

Fuel Tightness of Delivery Valve - Remove the engine stop solenoid. Remove the injection pipes and glow plugs. Set a pressure tester to the fuel injection pump. Turn the flywheel and raise the pressure to approx. 14.7 MPa (150 kgf/cm2, 2133 psi). Now turn the flywheel back about half a turn (to keep the plunger free). Maintain the flywheel at this position and clock the time taken for the pressure to drop from 14.7 to 13.7 MPa (from 150 to 140 kgf/cm2, from 2133 to 1990 psi). Measure the time needed to decrease the pressure from 14.7 to 13.7 MPa (from 150 to 140 kgflcm2 , from 2133 to 1990 psi). If the measurement is less than allowable limit, replace the delivery valve. Valve Seat Tightness - Set the injection nozzle to a nozzle tester. Raise the fuel pressure, and keep at 12.75 MPa (130 kgflcm2, 1849 psi) for 10 seconds. If any fuel leak is found, replace the nozzle piece.

Kubota B3030, B3350, B3150, B7800 - V1505 Engine Problems

Low compression

Low cylinder compression will result in insufficient heat being generated to ignite the fuel and cause hard starting. This is more of a problem with Kubota V1505 engines. A cold engine compression test should be performed. Compression should be between 20 to 35 bars, although it’s more important to have equal pressures, no more than ± 3 bar (50 psi) between cylinders. Anything below this will cause starting problems.

Low fuel pressure

Low fuel pressure could be either poor fuel supply to the injectors or the injectors are worn and not holding the fuel pressure. The best way to diagnose this is to look at the fuel supply in 3 areas. Low pressure supply from the tank to the fuel injection pump. The supply from the tank to the injection pump via the lift pump should be about 2 to 5 bar (30 to 70 psi). Fuel is delivered from the injection pump to the injectors at approx. 175 atmos. Once the fuel is delivered to the injectors at the relevant pressure it must lift the needle and spray finely atomized fuel into the cylinder.

Low cranking speed or Faulty battery

If the Kubota B3030, B3350, B3150, B7800 engine turns over too slowly, the injection pump can’t generate enough fuel pressure, and the piston speed will be too low to generate a high enough air temperature to initiate combustion, causing hard starting problems. This is usually in the colder months especially if the battery is run down, the tractor has been left sitting or if the battery terminals are corroded. The battery should be kept fully charged and all connections in good order.

Thermostart or Glow plugs faulty

The engine relies on the thermostart or glow plugs (If fitted), to heat the air in the combustion chamber while the engine is being cranked. Problems in this area will cause starting problems, uneven running and white smoke when the engine is cold.

Poor or low fuel supply

If there isn’t enough fuel in the tank or there’s a problem with the fuel pipes being split or kinked the fuel supply can be restricted. The fuel tank cap breather can sometimes be blocked causing a vacuum in the tank.

Contaminated fuel

Poor quality fuel and water in the fuel can cause injection pump and injector failure. Filters and sediment bowls must be changed and drained regularly. Diesel contaminated with other fuels is a fairly common problem. Most pump and injectors failures are due to fuel related issues.

Kubota B3030, B3350, B3150, B7800 - Air in fuel

Loose or faulty fuel pipe connections can allow air to be drawn into the system, but dirty fuel filters or a faulty filter head assembly may also cause fuel supply issues and hard starting. The bolt with the restriction hole must be in place between the leak off pipe and the filter head to build up back pressure in the injection pump, the leak off return pipe must go the bottom of the fuel tank.

Fuel filter or fuel pipes blocked

Dirty fuel containers/tanks/fuel can cause filters in the tank, lift pump and main filter to become blocked. They must be cleaned or changed on a regular basis.

Faulty injectors

The greatest cause of injector failure is due to the injectors having worn needles and nozzles or a build up of carbon. This can cause a poor spray pattern or fuel Dribble. This results in hard or poor starting. The injectors should be serviced or replaced at regular intervals. Diesel additives can help to clean injectors and fuel systems. Over time the injector springs can weaken.

Fuel pump faulty

Known faults in the pump are: Split diaphragms and leaking, loose or displaced non-return valves. If the pump is faulty there will be a Low fuel pressure problem, a split diaphragm will dilute the engine oil with diesel.

Blocked or Dirty air cleaner

A blocked or dirty air cleaner element can severely restrict air flow to the Kubota V1505 engine. Whether it’s an oil bath or dry element air cleaner it must be serviced at regular intervals.

Black Smoke

Faulty injectors. Faulty injector pump. Dirty or blocked air cleaner. Turbocharger faulty. Problems within the cylinder head or inlet valves not seating due to a build up of carbon. Over fueling.

White Smoke

Injection pump timing incorrect. Fuel starvation to the injection pump. Low engine compression. Water in the fuel. Water entering the combustion chamber. Faulty head gaskets and cracked cylinder liners and heads are a common cause of water entering the cylinder.

Blue Smoke

Worn cylinder liners or piston rings. Piston rings sticking. Faulty valves stem seals. Engine over full with engine oil. Dilution of the engine oil with fuel. Wrong Grade of oil, Too thin. The engine not being Worked hard enough, all diesel engines need hard work otherwise the cylinder bores can become Glazed.