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Home / Wheel Loaders / Case Wheel Loaders / Case 721

Case 721 Troubleshooting

The Case 721 wheel loader is powered by 505 cu.in (8.3L) Case 6T-830 4-stroke 6-cylinder direct injection turbocharged liquid-cooled diesel engine with a rated power of 140 hp (103.7 kW) at 2100 rpm. The Case 721 is equipped with a 4-speed powershift transmission, hydraulic power steering system, hydraulic wet disc brakes, and 20.5x25 standard tires. The open center hydraulic system has a gear pump with fluid flow rate of 30.9 gpm (117 lpm). The wheel loader has a rated operating capacity of 9920 lbs (4500 kg) and tipping load of 19840 lbs (9000 kg). The maximum lift height is 145" (3685 mm) to hinge pin, and bucket breakout force is 30240 lbs (13745 kg).

Engine Troubleshooting

Engine difficult to start or will not start
Air in fuel tank - Bleed fuel tank.
Fuel filter element is dirty - Service the filter.
Fuel injection nozzles are faulty or clogged - Check injection nozzles and replace if required.
Water in the fuel system - Change fuel and repair fuel system.
The valve clearance is not adjusted - Adjustment procedure required.
Fuel injection pump malfunction - Replace injection pump or repair it.

Diesel starts but immediately stops
Air cleaner is clogged - Clean or change.
Fuel filter element is clogged - Install new filter element.
Fuel injection pump leakage - Check the fuel injection pump for leaks and fix it.
Dirty or defective injectors - Replace or clean fuel injectors.
Defective fuel injection pump - Replace or rebuild injection pump.

Engine stalls while running
Engine is cold - Warm up to required temperature.
Dirty fuel filter - Change filter element.
Air in the fuel pipes - Bleed the fuel pipes.
Fuel injection nozzles fault - Replace injection nozzles.
Fuel injection pump timing is wrong - Adjust according to specifications.

Engine shuts off while idling
Low idle speed setting is not correct - Adjust the low idle speed.
Fuel injection pump failure - Change or repair the pump.
Fuel injector fault - Clean or replace fuel injectors.
Valve out of adjustment - Adjust valve clearance.

Engine power is too low
Clogged air cleaner - Clean or change.
Fuel injection nozzles are clogged or faulty - Test injection nozzles and change if necessary.
Uneven fuel injection pressure - Adjust to correct pressure.
Incorrect valve clearance - Need to adjust valve clearance.
Low idle speed setting is not correct - Adjust low idling as recommended.
Clogged fuel lines or hoses - Clean fuel system hoses and lines.
Blown cylinder head gasket - Gasket should be replaced.
Piston rings are damaged or leaking - Piston rings replacement required.

Engine overheating
Engine has a lack of coolant - Fill radiator to proper level and check components for faults.
Engine oil level is low - Check and refill engine oil.
Dirty radiator fins or faulty radiator cap - Clean radiator or install new cap.
Fan belt is worn or faulty - Belt change is required.
Engine is under excessive load - Load reducing is recommended.

Oil pressure is low
Insufficient engine oil - Fill crankcase to proper oil level.
Oil filter is clogged - Clean or change engine oil filter.
Oil grade or viscosity is incorrect - Fill up with the proper oil viscosity.
Incorrect oil clearance in main bearing - Change bearings.
Worn oil pump - Repair or change.

Engine noises or knocks
Not enough engine oil - Fill up the engine oil.
Coolant temperature is low - Warm up the engine.
Improper fuel injection timing - Set up as recommended.
Low idle speed adjustment is incorrect - Correct the settings.
Fuel injector fault - Clean or replace fuel injectors.
Faulty or misaligned connecting rod - Need to change or align the connecting rod.
Worn or scored pistons - Replace the pistons.

Transmission Troubleshooting

Low transmission fluid pressure
Insufficient transmission oil - Fill the transmission housing with oil.
Clogged transmission fluid filter (if equipped) - Clean or change transmission fluid filter.
Defective relief valve - Replace relief valve.

Transmission is excessively noisy
Lack of transmission fluid - Checking transmission fluid level and add if necessary.
Transmission fluid is contaminated - Change the fluid.
Defective gears or improper backlash - Adjust backlash properly or replace the gears.
Worn or cracked bearings - Replace faulty bearings.
Worn or damaged gear shift forks - Change the shift forks.
Worn or damaged shaft splines - Shaft need to be changed.

Hard shifts
Corroded or worn gear shift linkage - Install new shift linkage.
Worn or damaged gear shift forks - Change the shift forks.
Worn out parts of the gearshift mechanism - Replace worn parts.
Worn or unadjusted clutch - Adjust or change the clutch.

Transmission oil leaks
Transmission fluid level is high - Correct the fluid level.
Damaged gaskets or seals - Change defective seal or gaskets.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure incorrectly adjusted - Adjust it correctly.
Main relief valve is defective or unadjusted - Adjust or change relief valve.
Contaminated hydraulic oil - Hydraulic oil change required.
Not enough hydraulic oil in the system - Add oil to the hydraulic system.
Worn hydraulic oil pump - Repair or replace pump if necessary.

Boom can't lift or drop
Lift controls failure - Repair or replace.
Damaged hydraulic oil pump - Repair or change pump if required.
Faulty hydraulic control valve - Install a new valve or repair it.
Hydraulic cylinder not working - Replace or repair boom cylinder.
Low hydraulic fluid level - Fill up the hydraulic fluid.

Bucket is not working
Bucket tilt controls are defective - Replace or repair.
Hydraulic pump not working - Repair or change pump if required.
Faulty hydraulic control valve - Repair or change the valve.
Damaged bucket cylinder - Repair or install a new cylinder.
Low hydraulic fluid level - Fill the system to proper hydraulic fluid level.

Boom or bucket runs slowly
Worn hydraulic oil pump - Check pump flow and install new pump if necessary.
Leaking hydraulic cylinder - Replace cylinder piston seals.
Insufficient hydraulic fluid - Fill up the hydraulic fluid.
Faulty or incorrect setting hydraulic control valve - Repair or set correctly.
Hydraulic pressure has dropped - Set pressure correctly.

Lift arm or bucket is moving jerkily
There is air in the hydraulic system - Air bleeding is required.
Hydraulic oil filter is clogged - Change or clean oil filter.
Dirty hydraulic oil - Fill up with fresh hydraulic oil.
Cylinder tube or rod is scored - Replace damaged component.

Hydraulic pump is noisy
Hydraulic leaks or low oil level - Top up hydraulic oil or remedy leakage in system.
Dirty hydraulic filter - Replace or clean the filter.
Clogged suction line - Clean suction line as required.
Pump sucks air - Bleed air.
Pump components are damaged - Replace or rebuild the pump.

Electrical Troubleshooting

Battery does not charge
Loose or corroded cable connections - Clean or tighten wiring connections.
Defective battery terminal clamps - Replace terminal clamps.
Battery dead cell - Battery replacement required.
Damaged or loose belt - Adjust belt tension or replace belt.

Starter motor cranks slow
Low battery capacity - Battery is drained, recharge it.
Battery is draining quickly - Service charging system or replace battery.
Disconnected battery cables or bad terminals - Connect cables correctly or replace terminals.

Starter does not work
Battery is low or faulty - Replace or charge as required.
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed.
Battery power is low - Recharge the battery.
Defective starter motor - Repair or install a new starter.

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