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Home / Wheel Loaders / John Deere Wheel Loaders / John Deere 304H

John Deere 304H Troubleshooting

The John Deere 304H wheel loader driveline system components: 202.5 cu.in (3.3L) Yanmar 4TNE98 4-cylinder direct injection diesel engine with a rated power of 65 hp (48.5 kW), and hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 21.8 gal/min (82.5 l/min). The system relief pressure is 3045 psi (210 bar). The John Deere 304H is equipped with a power steering system, hydraulic dual disc brakes, and 405/70R20 tires. The wheel loader has a maximum lift height of 125" (3175 mm) and bucket breakout force of 10120 lbs (4590 kg). The rated operating capacity is 4320 lbs (1960 kg), and tipping load is 8640 lbs (3920 kg).

Engine Troubleshooting

Engine hard to start or will not start
Air in fuel system - Bleed fuel system.
Dirty fuel filter - Clean or change the filter.
Fuel injection nozzles are damaged or dirty - Check and replace nozzles if required.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve clearance is not correct - Check and adjust as required.
Damaged fuel injection pump - Rebuild or change fuel pump.

Engine starts but stalls suddenly
Air cleaner is clogged - Service or replace air cleaner.
Fuel filter element is dirty - Change filter element.
Poor fuel injection pump tightness - Look for any leaks of fuel pump, tighten it fast.
Clogged or defective injectors - Clean or replace fuel injectors.
Damaged fuel injection pump - Replacement or repair required.

Engine stops running suddenly
Engine not warmed up - Warm up engine as required.
Clogged fuel filter - Clean or replace the filter.
There is air in the fuel system - Bleed the system.
Clogged or defective injection nozzles - Inspect nozzles and replace if necessary.
Improper setting of fuel injection pump timing - Adjust according to specifications.

Engine stalls when idle
Too low idle RPM - Correct the settings.
Fuel injection pump is not operating properly - Replace or repair injection pump.
Fuel injectors are faulty or clogged - Replace or clean fuel injectors.
Valve clearance is out of adjustment - Adjust valve clearance.

Lack of engine power
Plugged air cleaner - Service or replace air cleaner.
Clogged injection nozzle - Change fuel injection nozzles.
Uneven fuel injection pressure - Adjust to proper pressure.
Valve clearance is out of adjustment - Check and adjust.
Wrong adjustment of low idle speed - Normalize low idle speed.
Fuel hoses or lines clogging - Clean fuel hoses and lines.
Cylinder-head gasket is broken - Gasket should be replaced.
Piston rings are defective or leaking - Replace the piston rings as required.

Engine overheated
Insufficient coolant fluid - Add coolant and check the components of cooling system.
Engine oil level low - Check and refill engine oil.
Dirty radiator fins or defective radiator cap - Replace cap or clean radiator.
Loose or damaged fan belt - Install new fan belt.
Diesel engine is overloaded - Reduce load on the engine.

Oil pressure too low
Low crankcase oil level - Need to add oil.
Plugged engine oil filter - Change or service engine oil filter.
Oil grade or viscosity is incorrect - Use proper viscosity oil.
Excessive oil clearance of crankshaft bearing - Replace bearings.
Oil pump is defective - Check and replace if necessary.

Abnormal engine noise or knocking
Low engine oil level - Check oil level and add oil as required.
Engine is not warmed up to required temperature - Normalize the temperature by warming up the engine.
Wrong setting of fuel injection pump timing - Set it up as required.
Incorrect low idle setting - Adjust the low idle speed.
Damaged or clogged injectors - Clean or replace fuel injectors.
Connecting rod is not aligned or defective - Connecting rod must be aligned or replaced.
Pistons are worn or scored - Have pistons replaced.

Hydrostatic Transmission Troubleshooting

Excessive hydrostatic transmission noise
Transmission oil is contaminated or oil level is insufficient - Change transmission oil or top up to proper level.
Worn or unadjusted speed control linkage - Change or adjust linkage.
Relief valve failure - Change relief valve.
Transmission overload - Reduce transmission load.
Damaged or worn components of hydrostatic transmission - After disassembly and inspection, replace defective components.

Loss of power
Low fluid level - Add fluid to the transmission housing.
Stuck relief valve - Replace relief valve.
Speed control linkage is defective or unadjusted - Adjust or replace linkage.

Transmission oil over heats
Transmission oil insufficient - Add oil to the transmission housing.
Dirty transmission fluid filter element - Service or replace the transmission fluid filter.
Cooling components are clogged or damaged - Check all cooling components and change or repair if required.
Excessive loading - Reduce transmission load.

Transmission fluid leaking
Seals or gaskets are worn - Seals and gaskets replacement required.
Transmission case internal pressure is too high - Change defective parts.
Oil return tube is plugged - Clean or replace the tube.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is incorrect - Correct setting is required.
Main relief valve failure or improper setting - Replace or set up the relief valve.
Dirty hydraulic fluid - Change hydraulic fluid.
Not enough hydraulic oil in the system - Fill up the hydraulic oil.
Faulty hydraulic oil pump - Repair or install new hydraulic pump.

Boom won't lower or raise
Lift controls are faulty - Check and repair as required.
Hydraulic pump malfunction - Replace or repair pump if necessary.
Hydraulic control valve is faulty - Change or repair hydraulic valve.
Hydraulic cylinder is broken - Change or repair lift cylinder.
Low hydraulic fluid level - Fill up the hydraulic fluid.

Bucket fails to tilt
Bucket tilt controls malfunction - Change or repair.
Hydraulic pump failure - Install new pump or repair it.
Faulty hydraulic control valve - Repair or change the valve.
Faulty hydraulic bucket cylinder - Change or repair cylinder.
Insufficient hydraulic fluid - Fill up the hydraulic fluid.

Boom or bucket is working slowly
Defective hydraulic pump - Check hydraulic pump flow and replace pump if necessary.
Leaking hydraulic cylinder - Cylinder seals need to be replaced.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.
Hydraulic control valve is unadjusted or worn - Repair or set properly.
Hydraulic pressure is low - Correct setting is required.

Lift arm or bucket movements are jerky
Air in hydraulic system - Air bleeding is required.
Hydraulic oil filter element is dirty - Change or clean oil filter.
Dirty hydraulic fluid - The fluid must be changed.
Scored cylinder tube or rod - Replace defective component.

Excessive hydraulic pump noise
Hydraulic system leaking or not enough oil - Repair hydraulic leaks or add oil as required.
Plugged hydraulic filter - Service or change hydraulic filter.
Suction line is clogged - Service the suction line.
Air trapped in hydraulic pump - Need to bleed air.
Worn pump parts - Replace or rebuild the pump.

Electrical Troubleshooting

Battery does not charge
Loose or corroded cable connections - Service or tighten connections.
Battery terminal connectors are faulty - Install new terminal connectors.
Battery bad cell - Battery replacement required.
Loose or worn belt - Install a new belt or adjust belt tension.

Starter cranks slowly
Battery capacity is low - Charge the battery.
Battery will not hold charge - Service charging system or install new battery.
Disconnected cables or faulty battery terminals - Check battery wires and service or replace terminals.

Starter does not work
Battery is low or faulty - Replace or charge as required.
Battery wiring is disconnected or improperly connected - Inspect wiring and connect as required.
Low battery capacity - Battery is drained, recharge it.
Damaged starter motor - Starter should be replaced.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders