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Home / Wheel Loaders / Case Wheel Loaders / Case 721B

Case 721B Troubleshooting

The Case 721B wheel loader driveline system components: a 505 cu.in (8.3L) Case 6T-830 six-cylinder turbocharged liquid-cooled diesel engine with a rated power of 140 hp (103.7 kW), and full powershift transmission with 4 forward and 3 reverse gears. The hydraulic system has a gear pump with a rated capacity of 56.4 gal/min (214 l/min). The Case 721B is equipped with an articulated steering system, hydraulic wet disc brakes, and 20.5x25 or 17.5x25 tires. The wheel loader has a max lift height to hinge pin of 145" (3685 mm) and breakout force of 30325 lbs (13780 kg). The rated operating capacity is 9840 lbs (4470 kg), and tipping load is 19675 lbs (8985 kg).

Engine Troubleshooting

Engine difficult to start or doesn't start
Air trapped in fuel system - Bleed air.
Fuel filter plugged - Clean or change the filter.
Fuel injection nozzles are faulty or clogged - Clean or replace injection nozzles.
Water in the fuel system - Change fuel and repair fuel system.
Improper valve clearance - Have it adjusted.
Damaged fuel injection pump - Replace or rebuild injection pump.

Engine starts and then shuts off
Plugged air filter - Clean or change filter.
Fuel filter element clogging - Clean or replace the filter.
Problems with fuel injection pump tightness - Inspect fuel injection pump for leaks.
Dirty or defective injectors - Change or clean fuel injectors.
Fuel injection pump is not working correctly - Install a new fuel pump or repair.

Engine stalls during operation
Coolant temperature is low - Warm up the engine.
Fuel filter element clogging - Clean or change the filter.
Air in fuel tank - Bleed fuel tank.
Defective or clogged injection nozzle - Clean or replace injection nozzles.
Fuel injection pump timing is wrong - Check the fuel injection pump timing adjustment.

Engine stops when idle
Low idle speed set incorrectly - Adjust as required.
Faulty fuel injection pump - Replacement or repair required.
Fuel injectors are faulty or clogged - Clean or replace fuel injectors.
The valve clearance is incorrect - Correct valve clearance needs to be set.

Engine power is too low
Clogged air cleaner - Install new air cleaner element.
Fuel injection nozzles are faulty or clogged - Check and replace nozzles if required.
Improper fuel injection pressure - Correct the pressure settings.
Incorrect valve clearance - Need to adjust valve clearance.
Low idle speed setting is not correct - Correct low idle adjustment.
Restricted fuel lines or hoses - Fuel hoses and lines must be clean.
Cylinder-head gasket is broken - Install a new gasket.
Worn or damaged piston rings - Replace piston rings.

Engine is overheated
Engine coolant is insufficient - Fill radiator to proper level and check components for faults.
Engine oil level low - Fill the crankcase with engine oil.
Defective radiator cap or clogged radiator core - Clean radiator or replace cap.
Fan belt is broken or worn - The fan belt needs to be replaced.
Engine overload - Reduce engine load.

Oil pressure is insufficient
Lack of oil - Fill up the engine oil.
Engine oil filter is plugged - Change or service engine oil filter.
Wrong oil viscosity - Drain and refill with oil of correct grade and viscosity.
Excessive crankshaft bearing oil clearance - Bearing needs to be changed.
Defective oil pump - Install a new pump.

Engine knocks or noises
Not enough engine oil - Check and refill engine oil.
Engine is not warmed up to required temperature - Warm up engine as required.
Improper fuel injection timing - Adjust as recommended.
Incorrect low idle speed adjustment - Correct the settings.
Clogged or defective injectors - Change or clean fuel injectors.
Connecting rod is worn or not aligned - Align or replace connecting rod.
Scored or worn pistons - Pistons replacement required.

Transmission Troubleshooting

Low transmission fluid pressure
Transmission oil level is low - Check transmission oil level and add oil as required.
Transmission oil filter is dirty (if equipped) - Service or change transmission oil filter.
Stuck relief valve - Change relief valve.

Transmission is excessively noisy
Lack of transmission fluid - Need to add transmission fluid.
Transmission oil is dirty - Transmission oil change required.
Gears are defective or backlash is improper - Adjust backlash properly or replace the gears.
Bearings are cracked or worn - Bearings need to be replaced.
Shift forks are worn or bent - Shift forks need to be changed.
Damaged or worn shaft splines - Install a new shaft.

Gear hard to shift
Gear shift linkage is corroded or worn - Install a new gear shift linkage.
Shift forks are worn or bent - Change the shift forks.
Gearshift mechanism is damaged - Replace or repair the mechanism.
Malfunction or incorrect clutch adjustment - Clutch needs to be replaced or adjusted.

Transmission oil leaks
Transmission oil level is high - Correct the oil volume.
Damaged seals or gaskets - Replace worn seal or gaskets.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is incorrect - Adjust pressure as required.
Main relief valve improper adjustment or failure - Adjust or replace the relief valve.
Hydraulic fluid is dirty - Change hydraulic fluid.
Lack of hydraulic fluid - Need to add fluid.
Worn hydraulic oil pump - Install new pump or repair it.

Lift arm can't drop or lift
Lift controls are defective - Replace or repair.
Damaged hydraulic oil pump - Install new pump or repair it.
Faulty hydraulic control valve - Repair or replace hydraulic valve.
Hydraulic cylinder failure - Repair or replace hydraulic cylinder.
Hydraulic fluid level low - Checking hydraulic fluid level and add if necessary.

Bucket does not function
Damaged bucket controls - Inspect and repair if necessary.
Hydraulic pump not working - Repair or replace pump if necessary.
Hydraulic control valve failure - Install a new hydraulic valve or repair it.
Defective bucket cylinder - Repair or change cylinder.
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.

Boom or bucket is working slowly
Faulty hydraulic oil pump - Check pump performance and change it if necessary.
Hydraulic cylinder leaking - Install new cylinder seals.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.
Hydraulic control valve is defective or set improper - Repair or set properly.
Hydraulic pressure is low - Adjust pressure as required.

Jerky operation of the bucket or boom
Hydraulic system is leaking air - Bleed air from system.
Hydraulic oil filter element is clogged - Clean or replace the filter.
Hydraulic fluid is contaminated - The fluid must be changed.
Cylinder rod or tube is scratched - Replace damaged component.

Excessive hydraulic pump noise
Lack of oil or hydraulic leakage - Refill hydraulic oil or repair leaks in system.
Dirty hydraulic filter - Clean or change the filter.
Suction line clogging - Clean suction line as required.
Pump sucks air - Bleed air from hydraulics.
Worn pump parts - Change or rebuild pump.

Electrical Troubleshooting

Battery cannot be charged
Loose or corroded cable connections - Service or tighten connections.
Battery terminal clamps are defective - Replace terminal clamps.
Battery faulty cell - Battery change required.
Belt is loose or defective - Adjust belt tension or change the belt.

Starter cranks slowly
Battery power is low - Recharge the battery.
Battery is not holding charge - Battery needs to be serviced or replaced.
Battery cables are disconnected or terminals are faulty - Connect wires properly or change terminals.

Starter is not cranking
Battery is drained or defective - Change or recharge battery.
Battery wires are disconnected or incorrectly connected - Check wires and connect correctly.
Low battery output - Battery is drained, recharge it.
Starter motor is defective - Repair or replace starter.

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