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Home / Wheel Loaders / Kubota Wheel Loaders / Kubota R520S

Kubota R520S Troubleshooting

The Kubota R520S wheel loader is powered by Kubota V2203-M-E3 vertical in-line 4-cylinder direct injection liquid-cooled diesel engine with a rated power of 45 hp (33.3 kW) at 2600 rpm. The Kubota R520S is equipped with a hydrostatic transmission, power steering system, wet disc brakes, and 15.5/60x18 or 12.5/80x18 tires. The hydraulic system has a pump with fluid flow rate of 15.4 gpm (58.3 lpm). The hydraulic pressure is 3000 psi (206 bar). The wheel loader has a rated operating capacity of 2200 lbs (1000 kg) and tipping load of 4400 lbs (2000 kg). The maximum lift height is 130.3" (3310 mm) to hinge pin, and breakout force is 6560 lbs (3375 kg).

Engine Troubleshooting

Engine hard to start or won't start
Air trapped in fuel system - Bleed air.
Fuel filter element is dirty - Filter maintenance required.
Fuel injection nozzles are faulty or clogged - Check and replace nozzles if required.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve clearance is wrong - Check and adjust.
Fuel injection pump damage - Replacement or repair required.

Engine starts but stops suddenly
Dirty air cleaner - Clean or change cleaner.
Fuel filter element is clogged - Service or replace the filter.
Fuel injection pump leakage - Check the fuel injection pump for leaks and fix it.
Damaged or clogged injectors - Clean or replace fuel injectors.
Damaged fuel injection pump - Change or repair the pump.

Engine stalls during operation
Coolant temperature is low - Warm up the engine.
Fuel filter plugging - Install new filter element.
Air trapped in fuel system - Bleed air.
Fuel injection nozzles are damaged - Install a new kit of correctly balanced nozzles.
Fuel injection pump timing is wrong - Adjust the pump as required.

Engine stalls when idling
Incorrect low idle speed adjustment - Adjust low idle speed.
Defective fuel injection pump - Repair or replace injection pump.
Fuel injectors are dirty or defective - Clean fuel injectors or change it.
Valve out of adjustment - Check and adjust.

Low engine power
Air cleaner is dirty - Install new air cleaner element.
Clogged injection nozzle - Clean or change injection nozzles.
Fuel injection pressure is incorrect - Test fuel injection pressure and adjust it correctly.
Incorrect valve clearance - Correct valve clearance.
Wrong adjustment of low idle speed - Adjust the low idle speed.
Restricted fuel lines or hoses - Fuel hoses and lines must be clean.
Damaged cylinder-head gasket - Replace the gasket as required.
Worn or damaged piston rings - Replace piston rings.

Engine is overheated
Engine has a lack of coolant - The cooling system needs to be refilled and checked for faults.
Low engine oil level - Check and refill engine oil.
Clogged radiator fins or leaking radiator cap - Change cap or clean radiator.
Loose or damaged fan belt - The fan belt needs to be replaced.
Engine overload - Load reducing required.

Oil pressure is low
Low oil level - Check oil level and add oil as required.
Oil filter element clogging - Clean or change engine oil filter.
Improper type of engine oil - Use correct viscosity oil.
Incorrect crankshaft bearing oil clearance - Bearings need to be reinstalled.
Oil pump is defective - Remove and inspect oil pump.

Engine noises or knocks
Engine oil insufficient - Fill up the engine oil.
Low coolant temperature - Warm up engine as required.
Fuel injection pump timing is not adjusted - Check the fuel injection pump timing adjustment.
Improperly adjusted low idle speed - Test and adjust.
Damaged or clogged injectors - Clean or replace fuel injectors.
Connecting rod is misaligned or defective - Connecting rod needs to be aligned or changed.
Worn or broken pistons - Pistons replacement required.

Hydrostatic Transmission Troubleshooting

HST transmission is making noise
Fluid is contaminated or fluid level is insufficient - Fill to required level or change the fluid.
Worn or out of adjustment speed control linkage - Replace or adjust linkage.
Stuck relief valve - Replace valve as required.
Transmission overload - Reduce loading.
Worn or defective parts of the hydrostatic transmission - After disassembly and inspection, replace defective components.

Low power
Transmission oil insufficient - Check and refill the transmission oil.
Relief valve malfunction - Replace valve as required.
Worn or unadjusted speed control linkage - Change or adjust linkage.

Transmission fluid overheats
Low oil level - Add oil to the transmission housing.
Dirty transmission fluid filter - Replace or service transmission fluid filter.
Cooling components are clogged or damaged - Check all cooling components and repair or change if required.
Transmission overload - Reduce transmission load.

Transmission fluid leakage
Seals or gaskets are worn - Gaskets or seal need to be replaced.
Transmission case internal pressure is too high - Change defective parts.
Oil drain pipe is plugged - Check pipe and service if necessary.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure is not correct - Adjust it correctly.
Defective or misadjusted main relief valve - Adjust relief valve or change if required.
Dirty hydraulic oil - The oil must be changed.
Not enough hydraulic fluid in the system - Check and refill the hydraulic fluid.
Faulty hydraulic oil pump - Change or repair hydraulic pump if required.

Lift arm does not lower or raise
Faulty lift controls - Replace or repair.
Hydraulic pump failure - Install new pump or repair it.
Damaged hydraulic control valve - Repair or change the valve.
Hydraulic cylinder is defective - Replace or repair boom cylinder.
Hydraulic fluid level low - Add fluid as required.

Bucket can't tilt
Damaged bucket controls - Inspect and repair if necessary.
Hydraulic pump failure - Repair or replace pump if necessary.
Defective hydraulic control valve - Repair or change the valve.
Hydraulic bucket cylinder is broken - Install a new cylinder or repair it.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.

Bucket or lift arm moves slowly
Defective hydraulic pump - Test the pump flow rate and install new pump if required.
Leaking hydraulic cylinder - Change cylinder piston seals.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.
Hydraulic control valve is faulty or out of adjustment - Repair or set correctly.
Low hydraulic pressure - Correct setting is required.

Lift arm or bucket is jerky
There is air in the hydraulic system - Bleed air from hydraulic system.
Hydraulic oil filter is clogged - Service or change the hydraulic filter.
Hydraulic oil is contaminated - The oil must be changed.
Cylinder tube or rod scoring - Replace damaged component.

Hydraulic pump is noisy
Hydraulic leakage or low oil level - Correct hydraulic leaks or top up oil as needed.
Hydraulic filter is clogged - Replace or clean the filter.
Suction line is clogged - Suction line must be serviced.
Air trapped in hydraulic pump - Air bleeding is required.
Damaged pump components - Change or rebuild pump.

Electrical Troubleshooting

Battery will not charge
Wiring connections are loose or corroded - Service or tighten cable connections.
Faulty battery terminal connectors - Change terminal connectors.
Battery is defective - Battery replacement required.
Worn or loose belt - Change belt or adjust belt tension.

Starter turns slow
Low battery output - Battery needs to be recharged.
Battery won’t hold charge - Service charging system or change battery.
Disconnected wires or corroded battery terminals - Connect wiring properly or install new terminals.

Starter will not work
Battery is low or faulty - Replace or charge as required.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery output - Battery is drained, charge it.
Starter motor is damaged - Repair or replace starter.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders