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Kubota L4630 Troubleshooting

Kubota L4630 Diesel Engine Troubleshooting

Engine difficult to start or won't start: Fuel filter element clogging. Install new filter element. Air in fuel tank. Bleed fuel tank. Faulty fuel injection nozzles. Install a new kit of correctly balanced nozzles. Defective fuel injection pump. Change pump or rebuild it.

Engine stops running suddenly: Fuel injection pump timing is not adjusted. Adjust according to specifications. Fuel filter plugged. Filter maintenance required. Engine has not warmed up to the recommended temperature. Warm up engine as required.

Diesel starts but immediately shuts off: Fuel filter element clogging. Change filter element. Fuel injection pump malfunction. Install a new fuel pump or repair. Air filter element clogged. Change air filter element.

Engine is overheated: Clogged radiator fins or leaking radiator cap. Clean radiator or change cap. Insufficient coolant fluid. Add coolant and check the components of cooling system. Fan belt is loose or defective. The fan belt needs to be replaced. Insufficient engine oil. Need to add engine oil.

Lack of engine power: Fuel injection nozzles are damaged or dirty. Change fuel injection nozzles. Dirty fuel hoses or lines. Clean fuel system lines and hoses. Intake air restriction. Carry out maintenance on air filter. Cylinder-head gasket is leaking. Change cylinder head gasket.

Engine noise or knocking: Coolant temperature is low. Engine is not warmed up to the required temperature. Engine oil insufficient. Add oil to the engine crankcase. Timing of fuel injection pump is incorrect. Set up as recommended. Pistons are worn or scored. Pistons replacement required. Misaligned or faulty connecting rod. Connecting rod must be aligned or replaced.

Engine stalls at low idle speed: Wrong adjustment of low idle speed. Normalize low idle speed. The valve clearance is not adjusted. Adjust valve clearance. Defective fuel injection pump. Rebuild or replace pump.

Oil pressure is low: Insufficient engine oil. Check and refill the oil. Oil pump is worn or damaged. Repair or change. Clogged oil filter element. Change or clean engine oil filter element.

Kubota L4630 Transmission Troubleshooting

Excessive transmission noise: Incorrect backlash or gears are worn. Install new gears and adjust backlash properly. Worn or bent shift forks. Shift forks need to be replaced. Shaft splines are damaged or worn. Install a new shaft. Insufficient transmission oil. Fill up the transmission oil. Worn or cracked bearings. Faulty bearings should be replaced. Transmission fluid is contaminated. Change the fluid.

Difficult to shift gears: Gear shift linkage is rusty or worn. Replace or lubricate the shift linkage. Malfunction or incorrect clutch adjustment. Adjust or install new clutch. Shift forks are bent or worn out. Shift forks need to be changed. Worn parts of the gear shifting mechanism. Change worn parts.

Transmission oil pressure is low: Low oil level. Need to add transmission oil. Transmission oil filter is dirty (if equipped). Clean or replace the transmission filter. Relief valve is damaged. Install a new valve.

Transmission fluid leakage: Worn seals or gaskets. Change defective gaskets or seal. Too much fluid in transmission. Excess fluid must be drained.

Hydrostatic Transmission Troubleshooting

HST transmission makes noise: Speed control linkage is worn or unadjusted. Adjust or repair linkage. Transmission overload. Load needs to be reduced. Fluid is contaminated or fluid level is insufficient. Pour fresh fluid or add transmission fluid to proper level. Relief valve malfunction. Change relief valve. Damaged or worn components of hydrostatic transmission. Replace or repair defective components.

Transmission oil overheats: Transmission overload. Load needs to be reduced. Plugged or defective cooling components. Check all cooling components and repair or change if required. Low oil level. Check and refill the transmission oil. Dirty transmission fluid filter. Clean or change transmission fluid filter.

Loss of power: Low oil level. Fill the transmission housing to proper oil level. Relief valve is stuck. Replace the valve. Speed control pedal linkage is bent or not adjusted. Adjust or replace linkage.

External oil leaks: Clogged oil return pipe. Clean or change return pipe. Damaged seals or gaskets. Seals and gaskets need to be replaced. High internal transmission case pressure. Check hydrostatic transmission components for defect or damage and change if necessary.

Kubota L4630 Hydraulics Troubleshooting

Hydraulic system is too hot: Wrong hydraulic oil type. Fill up with the correct type of oil. Hydraulic oil contamination. Change the oil. Air in the hydraulic system. Air bleeding. Main relief valve is faulty. Relief valve must be changed.

Hydraulic fluid pressure is low: Low hydraulic fluid level. Fill the system to proper hydraulic fluid level. Dirty hydraulic oil filter element. Clean the hydraulic filter element or replace if necessary. Leaks in hydraulic pipes. Identify leaks in the system and repair it. Incorrect setting hydraulic control valve block. Set correctly. Hydraulic pump malfunction. Install a new hydraulic fluid pump. Hydraulic cylinder is defective. Install a new hydraulic cylinder or repair it.

Hitch not lifting or hitch lifts slowly: Defective hydraulic pump. Replace or repair hydraulic fluid pump. Faulty main relief valve. Relief valve need to be replaced. Hydraulic spool valve is damaged. Install a new hydraulic valve or repair it. Broken hydraulic cylinder. Install a new hydraulic cylinder or repair it. Hydraulic fluid is insufficient. Fill up the hydraulic fluid. Dirty hydraulic fluid filter. Clean or replace the hydraulic filter. Excessive load on hitch. Load needs to be reduced.

3-point hitch can't drop or drops too slowly: Hydraulic cylinder failure. Repair or change hydraulic cylinder. Incorrect setting hydraulic spool valve. Use the correct setting. Hitch rock shaft is damaged. Replace the shaft. Three-point hitch has not been adjusted. Adjust the hitch.

Hitch lift or drop is jerky: Dirty hydraulic fluid. The fluid must be changed. Defective hydraulic pump. Replace or repair hydraulic fluid pump. Air in hydraulic pipes. Bleed hydraulic pipes. Hydraulic spool valve is defective. Install a new hydraulic valve or repair it. Hydraulic cylinder not working. Replace or repair hydraulic cylinder.

Kubota L4630 Steering System Troubleshooting

Excessive free play of steering wheel: Steering column shaft or coupling is worn out. Change defective component. Defective hydraulic steering pump. Install a new hydraulic steering pump. Loose or worn steering linkage parts. Repair or change steering linkage. Worn or defective hydrostatic steering unit. Check and replace as required.

Heavy steering: Air lock in hydraulic steering system. Bleed the system of air. Dirty steering filter. Clean or change it. Steering fluid level is low. Check fluid level and add steering fluid as required. Hydrostatic steering unit is worn or defective. Inspect and replace as required. Damaged hydraulic steering pump. Install a new hydraulic steering pump. Worn or stuck pump flow control valve. Replace or service control valve. Improperly installed or damaged steering column. Install the steering column as required or replace it. Front tires wear unevenly. Change the tires. Incorrect toe-in. Adjust toe-in properly. Steering cylinder leakage. Replace worn seal sleeves or damaged piston rod.

Tractor is pulling to left or right: Hydrostatic steering unit has wear or malfunction. Inspect and replace as required. Steering cylinder is defective. Repair or change hydraulic steering cylinder. Incorrect toe-in. Adjust toe-in wheels. Steering linkage joints are worn or loose. Repair or change steering linkage. Improperly adjusted or defective front hub bearings. Adjust properly or change bearings. Uneven tyre pressure. Inflate the tyres properly.

Kubota L4630 Electrical Troubleshooting

Battery does not charge: Corroded or loose cable connections. Service or tighten connections. Battery terminal clamps are faulty. Replace terminal clamps. Defective battery. Use a new battery. Belt is damaged or loose. Belt needs to be adjusted or changed.

Starter motor turns slow: Battery power is low. Low battery charging, charge as required. Battery drains quickly. Battery needs to be serviced or replaced. Disconnected battery cables or bad terminals. Connect wiring properly or install new terminals.

Starter is not cranking: Battery is discharged or defective. Charge or change the battery. Wiring is improperly connected or disconnected. Check wiring and connect properly. Battery voltage is low. Low battery charging, charge as required. Faulty starter motor. Repair or change starter.