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Kubota L4630 Troubleshooting
The
Kubota L4630 L30 series compact utility tractor was manufactured between 2003
and 2007. This model was designed in 4 versions: L4630DT (8-Speed), L4630GST
(12-Speed), L4630HST (Hydrostatic), and L4630GSTC (Cab).
The Kubota L4630 tractor is powered by 134.1 cu.in (2.2L) Kubota V2203
4-cycle vertical 4-cylinder indirect injection naturally aspirated
diesel engine with a rated power of 44.7 Hp (33.3 kW) and 146.2 Nm
(107.8 lb-ft) of maximum torque at 1600 rpm.
The Kubota L4630 is fitted with three transmission options: FST Sync
Shuttle fully synchronized transmission with 8 forward and 8 reverse
gears, Glide Shift fully synchronized transmission with 12 forward and 8
reverse gears, and 3-range hydrostatic transmission with infinite
forward and reverse gears. The maximum travel speed (forward/reverse):
18.7 mph (30 km/h) and 16.8 mph (27 km/h). The open center hydraulic
system used a gear pump with a rated capacity of 9.8 gal/min (37 l/min).
The hydraulic system pressure is 177 bar (2560 psi). The Kubota L4630 is
equipped with a hydrostatic power steering, wet disc brakes, 8.00x16 or
8.3x16 front tires, and 13.6x24 or 14.9x24 rear tires. The wheel base is
74.6" (1895 mm). The tractor is compatible with a
Kubota LA853 front-end
loader with lift capacity to full height of 2374 lbs (1076 kg) and
breakout force of 3125 lbs (1417 kg).
| Engine Troubleshooting |
| Engine will not start or difficult to start |
| Fuel filter plugging - Clean or replace the filter |
| Closed fuel cock - Open fuel on-off cock to inject fuel |
| Air in fuel pipes - Bleed fuel pipes |
| Dirty or damaged injectors - Inspect fuel injectors and replace if necessary |
| Fuel injection pump damage - Change pump or rebuild it |
| Bad engine compression - Check cylinder block and replace damaged components |
| Engine stops running unexpectedly |
| Engine is not warmed up to the required temperature - Warm up the engine |
| Water, dirt, or air in fuel system - Drain, flush, fill, and bleed system |
| Improper fuel injection - Fuel injection settings required |
| Dirty fuel filter element - Change filter element |
| Fuel injectors are damaged or dirty - Inspect fuel injectors and replace if necessary |
| Engine starts and immediately stalls |
| Fuel injection pump timing is incorrect - Check and correct adjustments |
| Fuel filter is clogged - Install new filter element |
| Clogged or damaged injector nozzles - Install new set of properly balanced nozzles |
| Fuel injection pump is not working correctly - Replace injection pump or repair it |
| Air cleaner clogging - Change or service air cleaner element |
| Low idle speed setting is incorrect - Correct low idle settings |
| Fuel injection pump is not operating properly - Rebuild or replace pump |
| Fuel injector nozzles are dirty or defective - Replace fuel injector nozzles |
| Improper valve clearance - Need to adjust valve clearance |
| Insufficient coolant fluid - Fill cooling system to proper level. Check for leaks or other malfunctions |
| Cooling system parts are worn or system is clogged - Replace faulty parts or service cooling system |
| Engine oil insufficient - Add oil to the engine crankcase |
| Fan belt tension is incorrect or belt is broken - Adjust belt tension properly or replace it |
| Defective or wrong type of thermostat - Check and replace if required |
| Fuel injectors are damaged or dirty - Clean or replace fuel injectors |
| Fuel injection pressure is incorrect - Adjust to correct pressure |
| Clogged air filter - Change or service air filter element |
| Clogged oil filter element - Clean or change engine oil filter |
| Engine overloaded - Reduce load or shift to lower gear |
| Valve out of adjustment - Adjust valve clearance |
| Low idle speed setting is not correct - Correct the settings |
| Dirt in the fuel pipes or hoses - Fuel pipes and hoses need to be cleaned |
| Loss of compression: Valves are faulty or leaking - Replace the valves |
| Abnormal engine noise or knocking |
| Unadjusted fuel injection pump timing - Adjust the fuel injection pump timing correctly |
| Clogged or defective injector nozzles - Install a new set of well-balanced nozzles |
| Engine oil level is insufficient - Fill up the engine oil |
| Coolant temperature is low - Warm up the engine as required |
| Crankshaft or main bearings are worn out - Worn parts replacement required |
| Piston rings are defective or broken - Replace piston rings |
| Loose flywheel bolts - Inspect flywheel bolts and tighten properly |
| Engine consuming too much oil |
| Oil leaks: Defective seals or gaskets - Replace defective parts |
| Oil viscosity is wrong - Fill up with the proper oil viscosity |
| Stuck or defective piston rings - Change piston rings |
| Damaged valve stems or valve guides - Change the valves |
| Scuffed pistons or cylinder liners - Check liners and pistons, replace as required |
| Electrical System Troubleshooting |
| Battery will not charge |
| Battery is defective - Battery change required |
| Battery wiring harness failure - Inspect electrical cables for defects, repair or replace |
| Corroded or loose battery terminals and cables - Tighten or clean cables and terminals |
| Worn belt or improperly adjusted belt tension - Change belt or correctly adjust belt tension |
| Low battery capacity - Low battery charging, charge as required |
| Battery won’t hold charge - Battery needs service or replacement |
| Battery electrical wire harness failure - Inspect wires for defects, change or repair |
| Battery cables and terminals are loose or corroded - Tighten or service cables and terminals |
| Battery capacity is low - Battery is drained, recharge it |
| Discharged or worn battery - Change or recharge battery |
| Starter motor is faulty - Starter needs to be replaced |
| Wiring is improperly connected or disconnected - Need to reconnect the wiring properly |
| Transmission Troubleshooting |
| Difficult to shift gears |
| Incorrectly adjusted or damaged clutch - Clutch needs to be replaced or adjusted |
| Stuck or damaged gear shift linkage - Change or repair shift linkage |
| Bent or worn shift forks - Replace defective shift forks |
| Faulty gear shifting mechanism - Faulty parts must be changed |
| Low transmission oil pressure |
| Not enough fluid in transmission - Add transmission fluid as required |
| Transmission oil filter is plugged (if fitted) - Change or service the transmission oil filter |
| Faulty relief valve - Change the valve |
| Bearings are worn or broken - Bearings need to be changed |
| Oil level is low - Checking transmission oil level and add if necessary |
| Contaminated transmission fluid - Change transmission fluid |
| Backlash is incorrect or gears are worn - Change worn gears or set backlash correctly |
| Worn or damaged shift forks - Replace defective shift forks |
| Gaskets or seals are defective Replace worn gaskets or seal |
| Transmission case is cracked - Replace case or transmission assembly |
| Hydraulics Troubleshooting |
| Excessive hydraulic system heat |
| Hydraulic system pressure is incorrect - Hydraulic pressure needs to be set correctly |
| Defective or misadjusted main relief valve - Adjust or replace the relief valve |
| Contaminated hydraulic fluid - Change hydraulic fluid |
| Air trapped in the hydraulic system - Check the suction pipe, fittings, and pump seals |
| Hydraulic oil pressure is low |
| Hydraulic fluid level is low - Need to add fluid |
| Hydraulic oil filter is dirty - Clean the hydraulic filter element or replace if necessary |
| Faulty hydraulic oil pump - Check the pump capacity and replace pump if required |
| Defective or incorrect setting hydraulic control valve block - Adjust properly or replace |
| Defective hydraulic cylinder - Check cylinder components for wear or damage and change if necessary |
| Leakage in hydraulic lines - Detect leaks in the system and fix it |
| Three-point hitch lifting is too slow or cannot be lifted |
| Lack of hydraulic fluid - Add fluid to the hydraulic system |
| Cold hydraulic fluid - Warm up the fluid |
| Hydraulic fluid filter element clogging - Clean or replace the hydraulic filter |
| Defective hydraulic pump - Check the pump capacity and replace pump if required |
| Faulty or incorrectly adjusted main relief valve - Adjust relief valve or change if required |
| Defective or not adjusted hydraulic spool valve - Change or adjust properly |
| Hydraulic cylinder is not working - Inspect the hydraulic cylinder parts for damage or wear and replace if required |
| Suction pipe is damaged or loose - Repair or change |
| Hitch won't lower or lowers slowly |
| Hydraulic spool valve is faulty or out of adjustment - Adjust properly or replace |
| Hydraulic cylinder is faulty - Inspect the hydraulic cylinder parts for damage or wear and replace if required |
| Worn lift arm shaft - Change the shaft |
| The hitch has mechanical faults - Replace defective or worn hitch parts |
| Hitch lower or lift is jerky |
| Air leaks in hydraulic system - Check the pump seals, suction line, and fittings |
| Hydraulic oil contamination - Change the oil |
| Hydraulic pump malfunction - Test the pump flow rate and install new pump if required |
| Hydraulic control valve block is faulty or out of adjustment - Adjust properly or replace |
| Hydraulic cylinder failure - Check the hydraulic cylinder parts for damage or wear and replace if necessary |
| Steering System Troubleshooting |
| Hard Steering |
| Defective or incorrectly installed steering column - Reinstall the steering column or change it |
| Air enters in steering system - Bleed the system of air |
| Improper toe-in adjustment - Check and adjust toe-in |
| Tires are not correctly inflated - Inflate tires as necessary |
| Steering pump failure - Steering pump needs to be replaced or repaired |
| Hydrostatic steering unit has wear or malfunction - Check and replace as required |
| Relief valve is faulty or stuck - Clean or change the relief valve |
| Steering oil level is low - Fill up steering oil to required level |
| Steering system oil leak - Retighten steering hose and pipe connections |
| Steering wheel free play is excessive |
| Steering column coupling or shaft is extremely worn out - Change faulty component |
| Hydrostatic steering unit has wear or malfunction - Check and replace as required |
| Steering pump stopped working - Install a new steering pump |
| Steering linkage or tie-rod ends are worn - Change damaged component |
| Tractor is pulling to left or right |
| Deflated front tyres - Inflate tyres as needed |
| Not adjusted toe-in - Adjust toe-in correctly |
| Worn or faulty steering tie-rod ends or linkage - Replace damaged component |
| Hydrostatic steering unit is defective or worn - Inspect and replace as required |
| Steering cylinder malfunction - Repair or change hydraulic steering cylinder |
| Defective or improperly adjusted front hub bearings - Change or adjust the bearings properly |
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| Farm Tractors Technical Specifications |
