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Home / Wheel Loaders / John Deere Wheel Loaders / John Deere 304K

John Deere 304K Troubleshooting

The John Deere 304K wheel loader driveline system components: Yanmar 4TNV98 4-cylinder vertical in-line direct injection liquid-cooled diesel engine with a rated power of 64 hp (48 kW), and hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 20 gal/min (75.8 l/min). The system relief pressure is 3335 psi (230 bar). The John Deere 304K is equipped with a power steering system, hydraulic wet disc brakes, and 405/70R20 tires. The wheel loader has a maximum lift height of 132.7" (3370 mm) and breakout force of 10560 lbs (4790 kg). The rated operating capacity is 3970 lbs (1800 kg), and tipping load is 7940 lbs (3600 kg).

Engine Troubleshooting

Diesel engine hard to start or doesn't start
Air in the fuel lines - Bleed the fuel lines.
Fuel filter element is dirty - Clean or change the filter.
Defective or clogged injection nozzle - Change fuel injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
Valve clearance is wrong - Check and adjust.
Fuel injection pump is defective - Replacement or repair required.

Engine starts but stops suddenly
Dirty air cleaner - Clean or change.
Fuel filter plugged - Change the filter element.
Fuel injection pump leakage - Check the fuel injection pump for leaks and fix it.
Clogged or defective injectors - Replace fuel injectors.
Fuel injection pump is broken - Change pump or rebuild it.

Engine stalls while running
Coolant temperature is low - Warm up to required temperature.
Fuel filter element is clogged - Change the filter element.
Air in the fuel pipes - Bleed the fuel pipes.
Fuel injection nozzles are dirty or defective - Service or change injection nozzles.
Timing of fuel injection pump is incorrect - Adjust fuel injection pump as required.

Engine stalls at idle
Low idle speed set incorrectly - Adjust low idling as recommended.
Fuel injection pump is damaged - Change or repair the pump.
Fuel injectors are dirty or defective - Clean or replace fuel injectors.
Improper valve clearance - Adjust to proper valve clearance.

Engine lacks power
Air filter is plugged - Change or service air filter element.
Fuel injection nozzles are damaged or dirty - Service or change injection nozzles.
Fuel injection pressure is incorrect - Adjust to proper pressure.
Improper valve clearance - Adjust valve clearance.
Low idle speed setting is not correct - Test and adjust.
Fuel hoses or lines are clogged - Service fuel lines and hoses.
Cylinder head gasket defective - Cylinder-head gasket replacement required.
Piston rings are leaking or defective - Replace piston rings.

Engine is overheated
Coolant level is low - The cooling system needs to be refilled and checked for faults.
Insufficient engine oil - Fill the crankcase with engine oil.
Faulty radiator cap or dirty radiator fins - Install new cap or clean radiator.
Excessive wear of the fan belt - Replace as required.
Diesel engine is overloaded - Load reducing is recommended.

Insufficient oil pressure
Engine oil level low - Fill the crankcase with oil.
Oil filter element clogged - Replace or service engine oil filter.
Improper type of engine oil - Use correct viscosity oil.
Excessive main bearing oil clearance - Bearings need to be reinstalled.
Oil pump malfunction - Remove and inspect oil pump.

Abnormal engine knocking or noise
Engine oil level is insufficient - Check and refill engine oil.
Engine is not fully warmed up - Warm up to required temperature.
Fuel injection pump timing is not adjusted - Set the fuel pump timing correctly.
Too low idle RPM - Adjust as required.
Fuel injector fault - Inspect fuel injectors and change as required.
Misaligned or defective connecting rod - Replace or align connecting rod.
Worn or broken pistons - Pistons replacement required.

Hydrostatic Transmission Troubleshooting

Hydrostatic transmission is making noise
Dirty transmission fluid or insufficient fluid level - Add fluid to the correct level or fill the transmission with fresh fluid.
Speed control linkage is defective or unadjusted - Repair or adjust linkage.
Relief valve is damaged - Replace the valve.
Transmission overloaded - The load should be reduced.
Transmission parts are worm or defective - Change or repair defective parts.

Power is too low
Lack of transmission oil supply - Add oil to the transmission housing.
Relief valve malfunction - Install a new relief valve.
Worn or out of adjustment speed control linkage - Adjust or install new linkage.

Transmission fluid overheats
Insufficient transmission fluid - Checking transmission fluid level and add if necessary.
Dirty transmission fluid filter - Clean or change transmission fluid filter.
Cooling components are defective or plugged - Check all cooling components and clean or replace if required.
Excessive transmission load - Load needs to be reduced.

Transmission oil leaking
Damaged gaskets or seals - Change defective gaskets or seal.
High internal transmission case pressure - Check transmission parts for damage or wear and replace if required.
Plugged transmission fluid return tube - Service or replace return tube.

Hydraulics Troubleshooting

Hydraulic system overheating
Incorrect hydraulic pressure setting - Correct adjustment is required.
Main relief valve is damaged or adjusted improperly - Adjust or change relief valve.
Dirty hydraulic oil - Change hydraulic oil.
Hydraulic oil level is insufficient - Fill the hydraulic system with oil.
Faulty hydraulic oil pump - Replace or repair pump if necessary.

Lift arm cannot be raised or lowered
Defective lift controls - Inspect and repair if necessary.
Damaged hydraulic oil pump - Install new pump or repair it.
Hydraulic control valve failure - Repair or change hydraulic valve.
Defective hydraulic cylinder - Replace or repair boom cylinder.
Hydraulic oil level low - Need to add oil.

Bucket does not tilt
Bucket controls are faulty - Repair or replace.
Hydraulic pump failure - Replace or repair pump if necessary.
Damaged hydraulic control valve - Repair or replace hydraulic valve.
Bucket cylinder failure - Repair or replace cylinder.
Hydraulic oil is insufficient - Checking hydraulic oil level and add if necessary.

Slow bucket or lift arm operation
Hydraulic pump is defective - Test pump performance and replace pump if necessary.
Hydraulic cylinder oil leakage - Repair leak by replacing the seals.
Insufficient hydraulic fluid - Fill up the hydraulic fluid.
Hydraulic control valve is faulty or out of adjustment - Set properly or repair.
Hydraulic pressure has dropped - Set pressure correctly.

Bucket or boom jerks when working
Hydraulic system is leaking air - Bleed air from system.
Hydraulic oil filter element clogging - Clean or change the filter.
Contaminated hydraulic fluid - Hydraulic fluid change required.
Cylinder tube or rod scoring - Change worn component.

Excessive hydraulic pump noise
Hydraulic leaks or lack of oil - Remedy hydraulic leakage or refill oil as necessary.
Hydraulic filter is clogged - Clean or change the filter.
Suction line is dirty - Need to service the suction line.
Air enters the pump - Remove air from hydraulics.
Faulty pump components - Change or rebuild pump.

Electrical Troubleshooting

Battery will not charge
Loose or corroded electrical wiring connections - Clean or tighten wiring connections.
Faulty battery terminal clamps - Install new terminal clamps.
Dead cell in battery - Change the battery.
Worn or loose belt - Adjust belt tension or change the belt.

Starter motor cranks slow
Low battery output - Low battery charging, charge as required.
Battery won’t hold charge - Service battery or replace it.
Faulty battery terminals or disconnected cables - Check cables and clean or change terminals.

Starter motor won't turn
Battery is drained or defective - Recharge or replace battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery output - Battery is drained, charge it.
Starter motor failing - Repair or replace starter.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders