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Kubota L4701HST Troubleshooting
The
Kubota L4701HST is a 4WD compact utility tractor from Standard L-series. This
model was manufactured between 2014 and 2021. The Kubota L4701HST powertrain
system components: Kubota V2403-CR-E4 4-cycle vertical 4-cylinder direct
injection naturally aspirated water-cooled diesel engine and 3-range hydrostatic
transmission with infinite forward and reverse gears.
A 148.5 cubic inches (2.4L) engine has a cylinder bore of 3.43" (87 mm),
piston stroke of 4.03" (102.4 mm), rated power of 47.3 hp (35.2 kW), and
maximum torque of 146.2 Nm (107.8 lb-ft) at 1400 rpm. Max forward speed
- 15.8 mph (25.4 kph), max reverse speed - 14.2 mph (22.9 kph). The open
center hydraulic system used a gear pump with a flow of 7.8 gpm (29.5
lpm). The hydraulic system pressure is 177 bar (2560 psi).
The Kubota L4701HST is equipped with a hydrostatic power steering
system, wet disc brakes, 8.3x16 front tires, and 14.9x24 rear tires. The
wheel base is 72.6 inches (1845 mm). The tractor can be equipped with
the following attachments: Kubota LA765 front-end loader with a maximum
lift height of 105.2 inches (2670 mm), and Kubota BH92 backhoe with 2-ft
flat digging depth of 106.1 inches (2690 mm).
| Engine Troubleshooting |
| Engine will not start or hard to start |
| Clogged fuel filter element - Change filter element |
| Fuel shut-off valve closed - Open the fuel shut-off valve |
| Air in fuel pipes - Bleed fuel pipes |
| Clogged or damaged injectors - Change fuel injectors |
| Fuel injection pump failure - Rebuild or replace pump |
| Engine has bad compression - Check cylinder block and replace defective parts |
| Diesel shuts off during operation |
| Engine has not warmed up to required temperature - Normalize the engine temperature |
| Fuel lines leaking air - Tighten clamps, change faulty pipes |
| Irregular fuel injection - Adjust fuel injection timing |
| Dirty fuel filter element - Change filter element |
| Dirty or damaged injectors - Check fuel injectors and replace if required |
| Engine starts and immediately stops |
| Unadjusted fuel injection pump timing - Fuel pump timing settings need to be corrected |
| Dirty fuel filter element - Change filter element |
| Clogged or damaged injector nozzles - Service or replace injector nozzles |
| Fuel injection pump is not operating properly - Install a new fuel pump or repair |
| Air cleaner element is clogged - Service or change air cleaner |
| Engine stalls while idling |
| Too low idle RPM - Need to adjust idle speed |
| Fuel injection pump is faulty - Replace injection pump or repair it |
| Clogged or defective injector nozzles - Service or replace nozzles if required |
| Valve clearance is not correct - Adjust valve clearance |
| Not enough coolant - Refill to the correct level. Check for coolant leaks |
| Cooling system parts are damaged or system is dirty - Service the cooling system or change faulty parts |
| Engine oil level low - Need to add engine oil |
| Fan belt tension is improper or belt is damaged - Adjust properly or change the belt |
| Defective or wrong type of thermostat - Check thermostat, replace if necessary |
| Fuel injectors are clogged or faulty - Test fuel injectors and change if necessary |
| Incorrect fuel injection pressure - Repair or replace injection pump |
| Air filter element clogging - Change or service air filter element |
| Engine oil filter is plugged - Replace or clean engine oil filter element |
| Diesel engine overloaded - Reduce the load or use a lower gear |
| Improper valve clearance - Adjust valve clearance |
| Incorrect low idle setting - Adjust low idle speed |
| Clogged fuel hoses or pipes - Clean fuel system hoses and pipes |
| Lack of compression: Valves are defective or worn - Valve replacement required |
| Incorrectly set fuel injection pump timing - Fuel pump timing settings need to be corrected |
| Fuel injector nozzles fault - Check and change nozzles as required |
| Low engine oil level - Check oil level and add oil as required |
| Engine is cold - Warm up the engine as required |
| Main bearings or crankshaft failure - Change or repair worn components |
| Piston rings are damaged or broken - Install new piston rings |
| Loose flywheel bolts - Check flywheel bolts and tighten properly |
| Diesel engine using too much oil |
| External oil leaks: Damaged seals or gaskets - Change to repair leaks |
| Incorrect oil viscosity - Use oil of correct viscosity |
| Worn or stuck piston rings - Change the piston rings as required |
| Worn valve stems and valve guides - Replace the valves |
| Pistons or cylinder liners are damaged - Inspect pistons and liners, fit new components as necessary |
| Electrical System Troubleshooting |
| Battery does not charge |
| Battery bad cell - Battery change required |
| Battery wiring harness failure - Inspect electrical cables for defects, repair or replace |
| Corroded or loose battery cables and terminals - Tighten or clean cables and terminals |
| Worn belt or improperly adjusted belt tension - Install new belt or adjust belt tension as required |
| Low battery voltage - Recharge the battery |
| Battery is not holding charge - Service charging system or change battery |
| Battery wiring harness damage - Inspect battery wiring for damage, replace or repair |
| Battery terminals and cables are loose or corroded - Tighten or service terminals and cables |
| Battery capacity is low - Low battery charging, charge as required |
| Drained or worn battery - Change or recharge battery |
| Faulty starter motor - Starter needs to be replaced |
| Wiring harness is disconnected or improperly connected - Check wiring harness and reconnect properly |
| Hydrostatic Transmission Troubleshooting |
| HST transmission makes excessive noise |
| Low fluid level or contaminated fluid - Change the transmission fluid or fill to required level |
| Speed control rod linkage is damaged or unadjusted - Adjust or change rod linkage |
| Relief valve failure - Change the valve |
| Transmission overload - Reduce loading |
| Damaged or worn transmission parts - Replace or repair worn components |
| Transmission fluid over heats |
| Low transmission fluid level - Check and refill the transmission fluid |
| Clogged transmission fluid filter element - Clean or replace the transmission fluid filter |
| Cooling components are plugged or defective - Check all cooling components and repair or change if required |
| Excessive transmission load - Reduce loading |
| Low transmission fluid level - Fill up the transmission fluid |
| Charge pressure is too low - Test charge pressure |
| Defective or worn relief valve - Install a new valve |
| Gaskets or seals are defective Change defective gaskets or seal |
| High pressure inside the transmission case - Repair or replace worn parts |
| Clogged transmission fluid drain line - Service or replace drain line |
| Hydraulics Troubleshooting |
| Hydraulic system overheating |
| Hydraulic system pressure is not set correctly - Set the hydraulic pressure as required |
| Main relief valve is damaged or adjusted improperly - Replace or set up the relief valve |
| Contaminated hydraulic fluid - Change hydraulic fluid |
| Air enters in hydraulic system - Check the suction pipe, fittings, and pump seals |
| Low hydraulic system pressure |
| Not enough hydraulic oil in the system - Add oil to the hydraulic system |
| Hydraulic oil filter clogging - Change hydraulic filter element or clean if necessary |
| Defective hydraulic pump - Test the pump flow rate and install new pump if required |
| Hydraulic spool valve block is faulty or out of adjustment - Set properly or replace |
| Hydraulic cylinder is broken - Check cylinder parts for wear or damage and replace if necessary |
| Hydraulic piping leaks - Detect leaks in the system and fix it |
| 3-point hitch lifts slowly or won't lift |
| Hydraulic oil level is insufficient - Add oil to the hydraulic system |
| Cold hydraulic oil - Warm up the oil |
| Hydraulic oil filter is dirty - Change hydraulic filter element or clean if necessary |
| Damaged hydraulic oil pump - Test pump flow rate and replace pump if required |
| Main relief valve is defective or unadjusted - Adjust or replace the relief valve |
| Hydraulic spool valve is faulty or out of adjustment - Adjust properly or change |
| Hydraulic cylinder is broken - Check cylinder parts for wear or damage and replace if necessary |
| Damaged or loose hydraulic suction line - Tighten or change it |
| 3-point hitch won't drop or drops slowly |
| Hydraulic spool valve block is faulty or out of adjustment - Change or set correctly |
| Hydraulic cylinder malfunction - Inspect cylinder components for damage or wear and change if required |
| Hitch rock shaft is damaged - Install a new shaft |
| The hitch has any internal mechanical damage - Change faulty or worn hitch components |
| Hitch is lowered or raised jerkily |
| Hydraulic system sucks air - Check the pump seals, suction pipe, and fittings |
| Contaminated hydraulic oil - Change hydraulic oil |
| Defective hydraulic pump - Test the pump flow rate and change pump if required |
| Defective or incorrect setting hydraulic control valve block - Replace or adjust properly |
| Defective hydraulic cylinder - Inspect cylinder components for wear or damage and change if required |
| Steering System Troubleshooting |
| Steering is hard |
| Damaged or improperly fitted steering column - Fit the steering column properly or change it |
| Air leaks in steering system - Bleed the system of air |
| Toe-in adjustment is incorrect - Check toe-in and correct |
| Deflated front tyres - Inflate tyres as needed |
| Steering pump not working - Check the steering pump and replace if necessary |
| Hydrostatic steering unit is defective or worn - Repair or change the steering unit |
| Relief valve failure or seizing - Inspect relief valve and replace if necessary |
| Steering fluid level low - Checking steering fluid level and add it if necessary |
| Steering system oil leakage - Retighten steering line and hose connections |
| Steering wheel free play is excessive |
| Worn steering column coupling or shaft - Replace defective part |
| Damaged or worn hydrostatic steering unit - Change or repair steering unit if required |
| Steering pump is faulty - Check the steering pump and replace if necessary |
| Steering tie-rod ends or linkage are defective - Change damaged component |
| Front wheels wander to right or left |
| Tires are improperly inflated - Inflate as necessary |
| Improper toe-in adjustment - Adjust toe-in wheels properly |
| Faulty or worn steering linkage or tie-rod ends - Replace failed component |
| Worn or defective hydrostatic steering unit - Repair or replace the steering unit |
| Steering cylinder is worn - Replace or repair steering cylinder |
| Front hub bearings are improperly adjusted or defective - Adjust correctly or change bearings |
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| Farm Tractors Technical Specifications |
