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Kubota L3901 Troubleshooting
The
Kubota L3901 is a compact utility tractor from Standard L series. This model was
manufactured between 2014 and 2021. The tractor was designed in 2 versions:
L3901F (2-wheel drive) or L3901DT (4-wheel drive).
The Kubota L3901 powerline system components: a 111.4 cu.in (1.8L)
Kubota D1803-CR-E4 3-cylinder direct injection liquid-cooled diesel
engine with a rated power of 37.5 hp (28.1 kW), and synchronized shuttle
transmission with 8 forward and 8 reverse gears. The maximum travel
speed (forward/reverse): 13.2 mph (21.2 km/h) and 13.1 mph (21.1 km/h).
The open center hydraulic system includes a gear pump with a flow rate
of 6.3 gal/min (23.9 l/min). The hydraulic pressure is 162 bar (2350
psi). The 2WD models are equipped with 5.00x15 front tires and 11.2x24
rear tires. The 7.2x16 or 27x8.50-15 front tires and 11.2x24 or 15x19.5
rear tires are used for 4WD tractors. The wheelbase is 63.3 inches (1610
mm). Compatible attachments for the tractor: a
Kubota LA525 front-end
loader with lift capacity to full height of 1131 lbs (513 kg), and
Kubota BH77 backhoe with 2-ft flat digging depth of 89.8 inches (2280
mm).
| Engine Troubleshooting |
| Engine won't start or starts hard |
| Fuel filter clogging - Service or replace the filter |
| Closed fuel supply valve - Open supply valve to inject fuel |
| Air in fuel system - Air-bleed fuel system |
| Dirty or faulty injectors - Inspect fuel injectors and replace if necessary |
| Fuel injection pump is not operating properly - Install a new pump or rebuild |
| Poor cylinder compression - Check and change damaged parts |
| Engine shuts off unexpectedly during operation |
| Engine is cold - Warm up the engine |
| Fuel lines leaking air - Tighten clamps, change faulty pipes |
| Uneven fuel injections - Repair or adjustment |
| Dirty fuel filter element - Change filter element |
| Clogged fuel injectors - Service or change fuel injectors |
| Diesel starts and then stalls |
| Fuel injection pump out of timing - Check the fuel injection pump timing setting |
| Dirty fuel filter element - Clean the filter or install new filter element |
| Fuel injector nozzles are damaged or dirty - Replace fuel injector nozzles |
| Fuel injection pump malfunction - Repair or install a new fuel pump |
| Air cleaner element is dirty - Change or replace air cleaner element |
| Engine stalls when idling |
| Low idle speed adjustment is incorrect - Adjust low idling as recommended |
| Fuel injection pump is faulty - Repair or replace injection pump |
| Damaged or clogged injector nozzles - Change or clean injector nozzles |
| The valve clearance is incorrect - Correct valve clearance |
| Low engine coolant - Top up coolant fluid. Any leaks must be repaired |
| Cooling system is clogged or cooling parts are defective - Service the cooling system or change faulty parts |
| Lack of engine oil - Fill up the oil to required level |
| Worn fan belt or incorrect belt tension - Adjust properly or replace the belt |
| Defective or wrong type of thermostat - Check thermostat, replace if necessary |
| Fuel injectors are clogged or faulty - Change fuel injectors |
| Improper fuel injection pressure - Adjust to correct pressure |
| Air filter element is dirty - Clean or replace the air filter element |
| Oil filter is dirty - Service or replace engine oil filter |
| Engine is running overloaded - Load reducing required |
| Valve clearance is out of adjustment - Adjust valve clearance according to specifications |
| Incorrect low idle speed adjustment - Correct low idle settings |
| Dirt in the hoses or pipes - Fuel pipes and hoses need to be cleaned |
| Insufficient engine compression: Leaking or faulty valves - Install new valves |
| Abnormal engine noise or knocking |
| Fuel injection pump out of timing - Adjust injection timing |
| Fuel injector nozzles are defective or dirty - Replace fuel injector nozzles |
| Engine oil level low - Add oil to the engine crankcase |
| Engine is cold - Warm up the engine to required temperature |
| Crankshaft or main bearings are worn out - Install new parts |
| Piston rings are worn or broken - Replace piston rings |
| Loose flywheel screws - Inspect the flywheel screws and tighten securely |
| High engine oil consumption |
| Oil leakage: Gaskets or seals are excessively worn - New components need to be installed |
| Oil viscosity is wrong - Use proper viscosity oil |
| Worn or broken piston rings - Have piston rings replaced |
| Valve guides or stems are damaged - Replace the valves |
| Cylinder liners or pistons are scuffed - Inspect liners and pistons, fit new parts as necessary |
| Electrical System Troubleshooting |
| Battery won’t charge |
| Defective battery - Install a new battery |
| Bad battery wiring harness - Inspect wiring for malfunctions, replace or repair |
| Loose or corroded terminals and cables - Terminals and cables need to be tightened or cleaned |
| Belt slipping or wrong belt tension adjustment - Adjust belt tension as required or change belt |
| Low battery output voltage - Battery is drained, recharge it |
| Battery is draining quickly - Service battery or replace it |
| Bad battery electrical wire harness - Check wires for malfunctions, repair or replace |
| Corroded or loose terminals and cables - Service or tighten battery terminals and cables |
| Low battery voltage - Battery needs to be recharged |
| Drained or faulty battery - Need to charge or replace the battery |
| Starter motor failure - Replace or repair starter |
| Disconnected or incorrectly connected cables - Need to reconnect cables correctly |
| Transmission Troubleshooting |
| Gear shift is hard |
| Failure or improper clutch adjustment - Adjust clutch or change if necessary |
| Damaged or loose gear shift linkage - Replace or repair the shift linkage |
| Worn or damaged shift forks - Install new shift forks |
| Gearshift mechanism failure - Change or repair failed components |
| Low transmission pressure |
| Oil level is low - Checking transmission oil level and add if necessary |
| Transmission oil filter element is dirty (if fitted) - Replace or service transmission oil filter |
| Relief valve sticking - Change the valve |
| Excessive transmission noise |
| Bearings are worn or cracked - Install new bearings |
| Insufficient oil supply - Fill the transmission housing to proper oil level |
| Transmission oil contamination - Change transmission oil |
| Gears are defective or backlash is incorrect - Set backlash correctly or change the gears |
| Worn or damaged shift forks - Shift forks need to be changed |
| Gaskets or seals are damaged - Replace worn seal or gaskets |
| Cracked transmission case - Install a new transmission case |
| Hydraulics Troubleshooting |
| Hydraulic system overheated |
| Hydraulic system pressure is incorrect - Hydraulic pressure needs to be set correctly |
| Misadjusted or defective main relief valve - Adjust the valve or replace if necessary |
| Hydraulic oil is dirty - Hydraulic oil change required |
| Air leaks in hydraulic system - Check the suction pipe, fittings, and pump seals |
| Insufficient hydraulic fluid pressure |
| Lack of hydraulic fluid - Need to add fluid |
| Hydraulic fluid filter is clogged - Clean the hydraulic filter element or replace if necessary |
| Hydraulic pump is faulty - Test pump performance and replace pump if necessary |
| Faulty or incorrect setting hydraulic control valve - Change or adjust correctly |
| Faulty hydraulic cylinder - Inspect the hydraulic cylinder parts for damage or wear and replace if required |
| Leakage in hydraulic lines - Detect leaks in hydraulic system and repair it |
| 3-point hitch does not raise or raises very slowly |
| Hydraulic fluid level is low - Add fluid to the hydraulic system |
| Hydraulic oil is too cold - Allow oil to warm |
| Hydraulic fluid filter element is dirty - Hydraulic filter maintenance required |
| Damaged hydraulic oil pump - Test the pump performance and change pump if required |
| Defective or misadjusted main relief valve - Adjust the valve or replace if necessary |
| Hydraulic control valve is defective or set improper - Adjust properly or change |
| Broken hydraulic cylinder - Check the hydraulic cylinder parts for damage or wear and replace if necessary |
| Damaged or loose suction line - Tighten or change |
| Hitch not dropping or hitch drops slowly |
| Hydraulic control valve block is defective or set improper - Set correctly or replace |
| Hydraulic cylinder is faulty - Inspect cylinder components for damage or wear and change if required |
| Damaged hitch rock shaft - Install a new shaft |
| Defective mechanical parts of the hitch - Replace defective or worn hitch parts |
| Hitch jerks when lower or lift |
| Air enters in hydraulic system - Check the suction line, pump seals, and fittings |
| Dirty hydraulic fluid - The fluid must be changed |
| Hydraulic pump failure - Test the pump performance and change pump if required |
| Hydraulic spool valve block is not set properly or defective - Replace or adjust correctly |
| Faulty hydraulic cylinder - Inspect the hydraulic cylinder parts for damage or wear and replace if required |
| Steering System Troubleshooting |
| Heavy steering |
| Steering column is worn or incorrectly mounted - Change the steering column or mount it correctly |
| Aeration in steering system - Air-bleed steering system |
| Improper toe-in - Adjust toe-in correctly |
| Low tire pressure - Inflate the tires |
| Steering pump stopped working - Repair or change steering pump |
| Defective or worn steering valve - Check and replace as required |
| Worn power steering box parts - Repair power steering gearbox |
| Insufficient steering oil - Need to add steering oil |
| Steering system has oil leaks - Retighten joints of the hydraulic steering pipes and hoses |
| Steering wheel has too much free-play |
| Steering column coupling or shaft is worn - Change defective part |
| Worn or damaged steering valve - Check and replace as required |
| Damaged power steering box parts - Change defective steering box parts |
| Steering pump stopped working - Check the hydraulic steering pump and change if necessary |
| Steering linkage or tie-rod ends are defective - Replace failed part |
| Tractor pulls to right or left |
| Tires are deflated - Need to inflate tires |
| Incorrect toe-in adjustment - Check and adjust toe-in |
| Faulty or worn steering tie-rod ends or linkage - Change failed component |
| Faulty power steering box parts - Change defective steering box parts |
| Damaged or worn steering valve - Inspect and replace as required |
| Front hub bearings are damaged or incorrectly adjusted - Adjust correctly or replace bearings |
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| Farm Tractors Technical Specifications |
