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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 |