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Kubota M120 Troubleshooting

Kubota M120 Diesel Engine Troubleshooting

Engine difficult to start or won't start: Clogged fuel filter. Clean or replace the filter. There is air in the fuel system. Bleed the system. Fuel injection nozzles are clogged or faulty. Check injection nozzles and replace if required. Fuel injection pump is defective. Repair or change injection pump.

Engine stalls during operation: Improper fuel injection timing. Use the correct fuel injection pump timing adjustment. Fuel filter plugging. Filter maintenance required. Engine is not fully warmed up. Engine is not warmed up to the required temperature.

Diesel starts but immediately shuts off: Fuel filter plugged. Replace the filter element. Faulty fuel injection pump. Rebuild or change fuel pump. Restricted intake air. Install new air filter element.

Engine overheating: Radiator fins are clogged or radiator cap is faulty. Clean radiator or change cap. Engine coolant is insufficient. Refill to the correct level and inspect system for leaks. Damaged or worn fan belt. Fan belt must be replaced. Lack of engine oil. Checking oil level and add if necessary.

Diesel power loss: Fuel injection nozzles are clogged or faulty. Inspect nozzles and replace if necessary. Restricted fuel hoses or lines. Clean fuel lines and hoses. Dirty air filter. Clean or change. Blown cylinder head gasket. Change cylinder head gasket.

Engine noises or knocks: Engine is cold. Warm up engine as required. Insufficient engine oil. Fill the crankcase with engine oil. Timing of fuel injection pump is incorrect. Check the fuel injection pump timing adjustment. Pistons are worn or scored. Have pistons replaced. Connecting rod misalignment or failure. Need to change or align the connecting rod.

Engine stalls at idle: Improperly adjusted low idle speed. Adjust as required. The valve clearance is incorrect. Adjust to proper valve clearance. Fuel injection pump damage. Repair or replace injection pump.

Low oil pressure: Insufficient engine oil. Checking oil level and add if necessary. Oil pump is damaged. Repair or change. Clogged oil filter. Service or replace engine oil filter.

Kubota M120 Transmission Troubleshooting

Transmission is making noise: Worn gears or incorrect backlash. Install new gears and adjust backlash properly. Worn or bent shift forks. Change defective shift forks. Shaft splines are stuck or worn out. Change the shaft. Lack of transmission oil supply. Need to add transmission oil. Worn or cracked bearings. Install new bearings. Transmission fluid contamination. Transmission fluid change required.

Gear hard to shift: Gear shift linkage is rusty or worn. Lubricate or replace the shift linkage. Unadjusted or worn clutch. Adjust or replace the clutch. Worn or bent shift forks. Change the shift forks. Worn out parts of the gearshift mechanism. Replace worn parts.

Insufficient transmission oil pressure: Transmission oil level is low. Fill the transmission housing to proper oil level. Transmission oil filter element clogging (if equipped). Service or replace the transmission oil filter. Defective relief valve. Replace relief valve as required.

Transmission oil leaks: Damaged gaskets or seals. Install new components. Transmission fluid level is high. Correct the fluid level.

Kubota M120 Hydraulics Troubleshooting

Hydraulic system is too hot: Hydraulic fluid type is incorrect. Pour the correct type of fluid. Hydraulic oil is dirty. Hydraulic oil change required. Air trapped in hydraulic system. Bleed air from system. Main relief valve malfunction. Relief valve must be changed.

Hydraulic oil pressure is low: Insufficient hydraulic fluid. Fill the system to proper hydraulic fluid level. Hydraulic oil filter is clogged. Clean or change hydraulic filter. Leaks in hydraulic lines. Identify leaks in the system and repair it. Incorrect setting hydraulic spool valve. Use the correct setting. Damaged hydraulic pump. Replace or repair hydraulic fluid pump. Faulty hydraulic cylinder. Replace or repair hydraulic cylinder.

3-point hitch fails to lift or lifts slowly: Defective hydraulic pump. Install a new hydraulic fluid pump. Main relief valve is defective. Relief valve replacement required. Hydraulic control valve block is defective. Repair or replace the valve. Hydraulic cylinder failure. Change or repair hydraulic cylinder. Hydraulic oil is insufficient. Fill the system to proper hydraulic oil level. Hydraulic fluid filter element is clogged. Replace filter element or clean if required. Excessive loading on the hitch. The load should be reduced.

Three-point hitch cannot be dropped or dropping is too slow: Hydraulic cylinder is broken. Repair or change hydraulic cylinder. Hydraulic control valve block is not set properly. Use the proper setting. Damaged hitch cross shaft. Replace the shaft. The hitch has not been adjusted. Adjust the 3-point hitch.

Jerky lifting or lowering of three-point hitch: Contaminated hydraulic fluid. Change hydraulic fluid. Faulty hydraulic pump. Change or repair hydraulic fluid pump. There is air in the hydraulic system. Bleed hydraulic system. Hydraulic spool valve is defective. Install a new hydraulic valve or repair it. Hydraulic cylinder not working. Repair or replace hydraulic cylinder.

Kubota M120 Steering System Troubleshooting

Excessive free play of steering wheel: Steering column coupling or shaft has maximum wear. Change defective component. Steering pump is worn. Repair or change steering pump. Loose or worn steering linkage components. Inspect and change as required. Power steering control valve has wear or damage. Inspect and replace as required.

Steering wheel turns hard: Air in steering hydraulic system. Air-bleed steering system. Steering filter is clogged. Change steering filter element. Low steering fluid level. Fill the steering system with fluid. Worn or damaged power steering control valve. Check and replace as required. Steering pump failure. Replace or repair steering pump. Stuck or damaged steering pump control valve. Flush or change flow control valve. Damaged or incorrectly assembled steering column. Replace steering column or assemble correctly. Tire pressure uneven. Inflate the tires correctly. Incorrect toe-in. Check toe-in and correct. Leaking steering cylinder. Replace damaged piston seals or worn piston rod.

Front wheels wander to left or right: Power steering control valve has damage or wear. Change or repair steering control valve if required. Steering cylinder malfunction. Change or repair steering cylinder. Improper toe-in. Check and adjust toe-in. Loose or worn steering linkage components. Inspect and replace as required. Improperly adjusted or defective front hub bearings. Adjust correctly or install new bearings. Tire pressure uneven. Inflate the tires correctly.

Kubota M120 Electrical System Troubleshooting

Battery won’t charge: Loose or corroded electrical wiring connections. Tighten or service cable connections. Battery terminal connectors are defective. Change terminal connectors. Battery bad cell. Battery change required. Defective or loose belt. Replace belt or adjust belt tension.

Starter turning slow: Low battery output. Low battery charging, charge as required. Battery does not hold charge. Battery needs to be serviced or replaced. Disconnected wires or corroded battery terminals. Check cable connections and change or clean terminals.

Starter will not crank: Battery is discharged or defective. Charge or replace the battery. Wiring is improperly connected or disconnected. Check wiring and connect properly. Low battery output. Battery is drained, charge it. Starter motor is faulty. Starter should be changed.