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Kubota B7400 Troubleshooting
The
Kubota B7400 is a 4-wheel drive compact utility tractor. This model was
manufactured between 2000 and 2003. The Kubota B7400 tractor is powered by 43.9
cubic inches (0.7 L) Kubota D722-E 3-cylinder indirect injection naturally
aspirated liquid cooled diesel engine with a maximum power of 16 Hp (11.9 kW)
and 44.7 Nm (33 lb-ft) of peak torque at 2600 rpm.
The Kubota B7400 is fitted with 2 transmission options: gear shift
transmission with 6 forward and 2 reverse gears, or 2-range hydrostatic
transmission with infinite forward and reverse gears.
Max. travel speed (forward and reverse): 11.7 mph (18.8 km/h) / 7.3 mph
(11.7 km/h). The open center hydraulic system used a single gear pump
with a flow rate of 3.9 gpm (14.8 lpm). The tractor was equipped with a
manual steering system, multi-plate wet disc brakes, 6.00x12 front
tires, and 8.3x16 rear tires. The wheel base is 59 in (1490 mm).
Compatible attachments for the Kubota B7400 tractor: 54", 60" mid-mount
3-blade side discharge rotary mower decks with cutting height of 1.5-4.0
in (30-100 mm), and Kubota LA272 loader with lift capacity to max height
of 685 lbs (310 kg).
| Engine Troubleshooting |
| Diesel will not start or hard to start |
| Fuel filter is dirty - Change filter element |
| Fuel supply valve is closed - Open fuel supply valve |
| Fuel lines leaking air - Tighten clamps, change faulty pipes |
| Dirty or damaged injectors - Clean or replace fuel injectors |
| Faulty fuel injection pump - Replace or repair injection pump |
| Low compression - Check and replace worn parts |
| Engine stops unexpectedly while running |
| Engine is not warmed up to the required temperature - Warmed up the engine as required |
| Air in fuel system - Air-bleed fuel system |
| Fuel injection failed - Use correct settings |
| Fuel filter is clogged - Replace filter element |
| Clogged fuel injectors - Clean or replace fuel injectors |
| Diesel starts and immediately stops |
| Fuel injection pump timing is incorrect - Fuel injection pump timing adjustment needs to be corrected |
| Fuel filter clogging - Replace filter element |
| Fuel injector nozzles are clogged or faulty - Service or replace injector nozzles |
| Fuel injection pump malfunction - Install a new fuel pump or repair |
| Dirty air cleaner - Change or replace air cleaner element |
| Too low idle RPM - Need to adjust idle speed |
| Fuel injection pump is not operating properly - Change pump or rebuild it |
| Fuel injector nozzles are defective or dirty - Check and change nozzles as required |
| Valve clearance is not correct - Need to adjust valve clearance |
| Lack of engine coolant - Top up coolant fluid. Inspect the system for leaks |
| Cooling system components are failed or system is dirty - Service the cooling system or replace faulty components |
| Engine oil level low - Fill the crankcase with engine oil |
| Fan belt is defective or belt tension is not adjusted - Adjust correctly or replace the belt |
| Defective thermostat - Check and replace if required |
| Fuel injectors are defective or dirty - Clean or replace fuel injectors |
| Incorrect fuel injection pressure - Check the fuel injection pressure and adjust if necessary |
| Air filter clogging - Service or change air filter |
| Oil filter element clogged - Clean or change engine oil filter |
| Diesel engine overloaded - Reduce engine load |
| The valve clearance is not adjusted - Need to adjust valve clearance |
| Wrong adjustment of low idle speed - Correct low idle adjustment |
| Fuel hoses or pipes clogging - Clean fuel pipes and hoses |
| Low engine compression: Intake or exhaust valves are damaged - Replace the valves as required |
| Fuel injection pump out of timing - Check and correct settings |
| Fuel injector nozzles are defective or dirty - Check and change nozzles as required |
| Engine oil level is low - Fill up the oil to required level |
| Low coolant temperature - Engine is not warmed up to the required temperature |
| Crankshaft or main bearings are worn out - Replace crankshaft or bearings |
| Broken or worn piston rings - Have piston rings replaced |
| Flywheel screws are loose - Tighten the screws firmly |
| Oil leaks: Gaskets or seals can be faulty - Change to repair leaks |
| Crankcase oil too light - Fill up with the correct oil viscosity |
| Piston rings are stuck or broken - Change piston rings |
| Valve stems or guides are damaged - Need to replace the valves |
| Scored pistons or cylinder liners - Inspect pistons and liners, replace as required |
| Electrical System Troubleshooting |
| Battery is not charging |
| Faulty cell in battery - Battery replacement required |
| Battery wiring harness damage - Inspect battery wiring for damage, replace or repair |
| Corroded or loose terminals and cables - Service or tighten battery cables and terminals |
| Belt damage or incorrect belt tension adjustment - Adjust belt tension correctly or change belt |
| Battery power is low - Recharge the battery |
| Battery won’t hold charge - Battery needs service or replacement |
| Bad battery electrical wire harness - Check wires for malfunctions, repair or replace |
| Battery cables and terminals are loose or corroded - Cables and terminals must be tightened or cleaned |
| Low battery power - Recharge the battery |
| Drained or faulty battery - Recharge or replace battery |
| Starter motor is damaged - Starter needs to be changed |
| Disconnected or incorrectly connected wiring harness - Inspect wiring harness and reconnect it as required |
| Hydrostatic Transmission Troubleshooting |
| HST transmission makes noise |
| Oil level is insufficient or oil is contaminated - Top up to proper level or change oil |
| Damaged or not adjusted speed control rod linkage - Repair or adjust link rod linkage |
| Relief valve failure - Replace relief valve |
| Transmission is under excessive load - Reduce transmission load |
| Worn or damaged parts of the hydrostatic transmission - Change or repair damaged parts |
| Transmission fluid overheated |
| Oil level is low - Checking transmission oil level and add if necessary |
| Transmission fluid filter is dirty - Replace or clean transmission fluid filter |
| Cooling components are clogged or damaged - Inspect all cooling components and service or replace if necessary |
| Excessive loading - The load should be reduced |
| Oil level is low - Correct the transmission oil level |
| Low charge pressure - Test charge pressure |
| Relief valve is worn or defective - Install a new valve |
| Broken gaskets or seals - Install new gaskets or seal |
| High pressure inside the transmission case - Replace or repair defective components |
| Clogged oil return tube - Service or replace return tube |
| Hydraulics Troubleshooting |
| Hydraulic system overheats |
| The system pressure has not been corrected - Make the correct settings |
| Defective or misadjusted main relief valve - Replace or set up the relief valve |
| Dirty hydraulic fluid - The fluid must be changed |
| Hydraulic system sucks air - Inspect the suction line, pump seals, and fittings |
| Hydraulic fluid pressure is insufficient |
| Lack of hydraulic fluid - Fill the hydraulic system with oil |
| Hydraulic oil filter element is dirty - Replace filter element or clean if required |
| Hydraulic pump is defective - Test the pump performance and change pump if required |
| Defective or incorrect setting hydraulic control valve block - Set properly or replace |
| Hydraulic cylinder is defective - Inspect the hydraulic cylinder parts for damage or wear and replace if required |
| Leakage in hydraulic lines - Identify leaks in the system and repair it |
| Three-point hitch lifting is too slow or cannot be lifted |
| Not enough hydraulic fluid in the system - Add fluid to the hydraulic system |
| Hydraulic fluid is too cold - Allow fluid to warm |
| Hydraulic oil filter element is dirty - Change hydraulic filter element or clean if necessary |
| Hydraulic pump failure - Check pump flow and install new pump if necessary |
| Main relief valve incorrect adjustment or failure - Adjust or change relief valve |
| Damaged or incorrect adjusted hydraulic spool valve - Adjust correctly or change |
| Hydraulic cylinder failure - Check the hydraulic cylinder parts for damage or wear and replace if necessary |
| Suction pipe is broken or loose - Tighten the pipe or replace it |
| 3-point hitch fails to drop or drops slowly |
| Hydraulic spool valve is not set properly or defective - Adjust properly or change |
| Hydraulic cylinder is faulty - Check cylinder components for damage or wear and change if necessary |
| Lift arm shaft is damaged - Change the shaft |
| The hitch has internal mechanical malfunctions - Replace faulty or worn hitch parts |
| 3-point hitch lift or lower is jerky |
| Air in hydraulic system - Check the suction line, pump seals, and fittings |
| Hydraulic fluid is dirty - Hydraulic fluid change required |
| Hydraulic pump is defective - Flow-rate hydraulic pump and replace pump if necessary |
| Faulty or incorrect setting hydraulic control valve - Adjust correctly or replace |
| Hydraulic cylinder is broken - Inspect cylinder parts for wear or damage and replace if required |
| Steering System Troubleshooting |
| Hard Steering |
| Steering knuckle or steering column is stuck - Inspect steering column and knuckle, replace worn parts |
| Steering gearbox components are worn - Replace defective components of steering gearbox |
| Faulty drag link or tie rod - Replace or repair |
| Insufficient lubrication in steering box - Need to lubricate the gearbox |
| Not adjusted toe-in alignment - Check and adjust toe-in |
| Tires are not correctly inflated - Inflate tires as necessary |
| Excessive steering wheel free play |
| Steering column bearing or shaft is worn - Change faulty parts |
| Steering linkage assembly is worn or loose - Repair or replace steering linkage |
| Worn steering gearbox bearings - Replace the bearings |
| Front wheel hub bearings or steering knuckles are worn - Change hub bearings or knuckles |
| Damaged or worn steering tie-rod ends - Change faulty part |
| Tractor pulls to right or left |
| Worn or loose steering linkage assembly - Repair or replace steering linkage |
| Defective steering knuckle bushing - Replace knuckle bushing |
| Uneven tire pressure - Inflate the tires properly |
| Toe-in adjustment is incorrect - Adjust toe-in correctly |
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| Farm Tractors Technical Specifications |
