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Kubota R420 Troubleshooting
The
Kubota R420 wheel loader driveline system components: a 91.4 cu.in (1.5L) Kubota
D1503-M-T-E2 3-cylinder turbocharged diesel engine with a rated power of 39.5 hp
(29 kW), and hydrostatic transmission. The hydraulic system has a pump with a
rated capacity of 11.1 gal/min (42.1 l/min). The system relief pressure is 3000
psi (206 bar). The Kubota R420 is equipped with a power steering system, wet
disc brakes, and 12.5/70x16 or 33x12.50x15 tires. The wheel loader has a max
lift height of 110.6" (2810 mm) and breakout force of 6560 lbs (2980 kg). The
rated operating capacity is 2210 lbs (1005 kg), and tipping load is 4420 lbs
(2010 kg).
| Engine Troubleshooting |
Engine starts hard or won't start
Air in the fuel pipes - Bleed the fuel pipes.
Fuel filter element clogging - Clean the filter element.
Faulty or dirty injection nozzles - Clean or replace injection nozzles.
Water in the fuel system - Change fuel and repair fuel system.
Valve clearance is wrong - Adjust valve clearance according to specifications.
Damaged fuel injection pump - Install a new pump or rebuild.
Diesel starts but immediately shuts off
Air filter is clogged - Clean or replace element.
Fuel filter plugging - Change filter element.
Fuel injection pump is leaking - Repair any leaks.
Dirty or defective injectors - Test and replace fuel injectors if necessary.
Fuel injection pump failure - Replace injection pump or repair it.
Engine stops unexpectedly during operation
Coolant temperature is low - Warm up to required temperature.
Clogged fuel filter - Install new filter element.
Air in fuel system - Bleed fuel system.
Faulty or dirty injection nozzles - If necessary, replace with a new nozzle.
Wrong setting of fuel injection pump timing - Adjust according to specifications.
Engine stalls when idling
Improperly adjusted low idle speed - Correct low idle settings.
Fuel injection pump malfunction - Change or repair the pump.
Fuel injector fault - Replace or clean fuel injectors.
Valve clearance is wrong - Have it adjusted.
Engine power is too low
Air cleaner is clogged - Clean or replace air cleaner element.
Fuel injection nozzles are dirty or defective - Test injection nozzles and change if necessary.
Improper fuel injection pressure - Check the fuel injection pressure and adjust if necessary.
Excessive valve clearance - Correct valve clearance needs to be set.
Low idle speed setting is not correct - Correct low idle adjustment.
Fuel hoses or lines are dirty - Service fuel lines and hoses.
Defective cylinder head gasket - Replace the gasket as required.
Worn or broken piston rings - Install new piston rings.
Engine overheated
Lack of engine coolant - Fill radiator to proper level and check components for faults.
Engine oil level is low - Fill up the oil to required level.
Radiator core is dirty or radiator cap is damaged - Replace cap or clean radiator.
Loose or defective fan belt - Replace as required.
Engine is overloaded - Load reducing required.
Low oil pressure
Low oil level - Add oil as required.
Oil filter is clogged - Service or replace engine oil filter.
Oil grade or viscosity is incorrect - Use oil of correct viscosity.
Excessive oil clearance of crankshaft bearing - Bearing needs to be changed.
Oil pump malfunction - Inspect and change as required.
Engine knocks or noises
Low engine oil level - Check and refill engine oil.
Engine not warmed up - Normalize the temperature by warming up the engine.
Improper fuel injection timing - Set the fuel pump timing correctly.
Incorrectly adjusted low idle speed - Normalize low idle speed.
Fuel injectors are dirty or defective - Change or clean fuel injectors.
Misaligned or defective connecting rod - Align or replace connecting rod.
Pistons are broken or worn - Have pistons replaced.
| Hydrostatic Transmission Troubleshooting |
HST transmission makes noise
Transmission fluid is dirty or fluid level is too low - Fill to required level or change the fluid.
Speed control pedal linkage is damaged or out of adjustment - Replace or adjust linkage.
Defective relief valve - Install a new relief valve.
Transmission is under excessive load - The load should be reduced.
Damaged or worn components of hydrostatic transmission - Replace or repair defective components.
Power is insufficient
Lack of transmission oil supply - Add oil to the transmission housing.
Relief valve failure - Replace relief valve.
Worn or unadjusted speed control linkage - Adjust or replace linkage.
Transmission oil overheats
Transmission fluid insufficient - Add fluid to the transmission housing.
Dirty transmission oil filter element - Clean or replace the transmission filter.
Defective or plugged cooling components - Check all cooling components and change or repair if required.
Transmission overloaded - Reduce loading.
Transmission fluid leaks
Damaged seals or gaskets - Install new gaskets or seal.
Transmission case internal pressure is too high - Repair or replace damaged components.
Plugged transmission fluid return tube - Service or replace return tube.
| Hydraulics Troubleshooting |
Hydraulic system overheats
Incorrect hydraulic pressure setting - Correct setting is required.
Main relief valve is damaged or adjusted improperly - Set up or change the relief valve.
Hydraulic oil contamination - Hydraulic oil change required.
Lack of hydraulic fluid - Add fluid to the hydraulic system.
Hydraulic pump is defective - Repair or install new hydraulic pump.
Boom can't lift or drop
Lift controls are faulty - Repair or replace.
Hydraulic pump malfunction - Repair or replace pump if necessary.
Hydraulic control valve is faulty - Replace or repair the valve.
Hydraulic cylinder malfunction - Change or repair lift cylinder.
Hydraulic oil level low - Check and refill the hydraulic oil.
Bucket can't tilt
Bucket controls failure - Repair or change.
Hydraulic pump malfunction - Repair or install new hydraulic pump.
Faulty hydraulic control valve - Replace or repair the valve.
Bucket cylinder failure - Replace or repair cylinder.
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Boom or bucket is working slowly
Hydraulic pump is defective - Check pump flow and install new pump if necessary.
Oil leaks from hydraulic cylinder - Cylinder seals need to be replaced.
Low hydraulic fluid level - Fill the system to proper hydraulic fluid level.
Hydraulic control valve is not set properly or defective - Repair or adjust correctly.
Hydraulic system loosing pressure - Set pressure correctly.
Bucket or boom is jerky
Air in the hydraulic system - Need to bleed air.
Hydraulic oil filter element is dirty - Change or clean oil filter.
Hydraulic oil contamination - Hydraulic oil change required.
Cylinder rod or tube is scratched - Change damaged component.
Hydraulic pump is excessively noisy
Low oil level or hydraulic leaks - Add hydraulic oil or correct system leaks.
Hydraulic filter is dirty - Service or replace hydraulic filter.
Suction line is dirty - Need to clean the suction line.
Pump sucks air - Remove air from hydraulics.
Worn pump parts - Install new hydraulic pump or rebuild it.
| Electrical Troubleshooting |
Battery will not charge
Corroded or loose wire connections - Clean or tighten wiring connections.
Faulty battery terminal connectors - Change terminal connectors.
Faulty cell in battery - Replace the battery.
Belt is loose or defective - Replace belt or adjust belt tension.
Starter cranks slowly
Low battery voltage - Recharge the battery.
Battery won’t hold charge - Battery needs service or replacement.
Faulty battery terminals or disconnected cables - Check wiring and clean or replace terminals.
Starter is not cranking
Battery is discharged or defective - Recharge or replace battery.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Low battery capacity - Charge the battery.
Starter motor failure - Change or repair starter.
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| WHEEL LOADERS SPECIFICATIONS |
Bobcat
Caterpillar
Case
Doosan
John Deere
Kubota