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Home / Wheel Loaders / Case Wheel Loaders / Case 621D XT

Case 621D XT Troubleshooting

The Case 621D XT wheel loader is powered by Case 6BT-590 6-cylinder turbocharged liquid-cooled diesel engine with a rated power of 134 hp (99.3 kW) at 2200 rpm. The Case 621D XT is equipped with a 4x3 powershift transmission, power steering system, hydraulic wet disc brakes, and 20.5x25 standard tires. The hydraulic system has a pump with fluid flow rate of 45.2 gpm (171 lpm). The hydraulic pressure is 3600 psi (248 bar). The wheel loader has a rated operating capacity of 7375 lbs (3345 kg) and tipping load of 14750 lbs (6690 kg). The max lift height is 156.9 inches (3985 mm) to hinge pin, and boom breakout force is 26055 lbs (11820 kg).

Engine Troubleshooting

Engine difficult to start or doesn't start
Air in the fuel pipes - Bleed the fuel pipes.
Fuel filter element is clogged - Change filter element.
Clogged or burnt injection nozzle - Clean or change injection nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Improper valve clearance - Have it adjusted.
Fuel injection pump failure - Install a new pump or rebuild.

Diesel starts but immediately stops
Plugged air cleaner - Clean or change cleaner.
Dirty fuel filter - Replace the filter element.
Fuel injection pump leakage - Check the fuel injection pump for leaks and fix it.
Defective or clogged fuel injectors - Clean or replace fuel injectors.
Fuel injection pump malfunctioning - Install a new pump or rebuild.

Engine stops unexpectedly during operation
Engine is not warmed up to required temperature - Warm up engine as required.
Clogged fuel filter - Change the filter element.
Air trapped in fuel system - Bleed air.
Clogged or defective injection nozzles - Check injection nozzles and replace if required.
Incorrect adjustment of fuel injection pump timing - Set the fuel pump timing correctly.

Engine stops when idling
Low idle speed setting is incorrect - Need to adjust idle speed.
Fuel injection pump is defective - Rebuild or change fuel pump.
Dirty or defective injectors - Replace or clean fuel injectors.
Valve clearance is not correct - Adjustment procedure required.

Low engine power
Air cleaner is clogged - Clean or replace air cleaner element.
Fuel injection nozzles fault - Inspect nozzles and replace if necessary.
Fuel injection pressure is incorrect - Adjust to correct pressure.
Valve clearance is wrong - Adjust valve clearance according to specifications.
Improperly adjusted low idle speed - Correct the settings.
Fuel lines or hoses are dirty - Clean fuel hoses and lines.
Cylinder-head gasket is leaking - Gasket should be replaced.
Worn or damaged piston rings - Install new piston rings.

Engine is overheated
Insufficient coolant - Fill radiator to proper level and check components for faults.
Engine oil level is insufficient - Need to add engine oil.
Defective radiator cap or clogged radiator fins - Replace cap or clean radiator.
Loose or damaged fan belt - Install new fan belt.
Diesel engine overloaded - Reduce load on the engine.

Oil pressure is insufficient
Not enough oil in the engine - Fill the crankcase with oil.
Oil filter element is dirty - Change or clean engine oil filter element.
Wrong oil viscosity - Use proper viscosity oil.
Incorrect crankshaft bearing oil clearance - Bearings need to be reinstalled.
Oil pump failure - Repair or change.

Engine knocking sound or abnormal noise
Engine oil level is insufficient - Add oil to the engine crankcase.
Engine not warmed up - Warm up to required temperature.
Improper fuel injection timing - Adjust as recommended.
Incorrect low idle setting - Test and adjust.
Fuel injectors are faulty or clogged - Change or clean fuel injectors.
Connecting rod is defective or misaligned - Need to replace or align the connecting rod.
Pistons are worn or scored - Replace the pistons.

Transmission Troubleshooting

Transmission fluid pressure is insufficient
Transmission fluid insufficient - Fill the transmission housing to proper fluid level.
Transmission fluid filter element is clogged (if equipped) - Replace or service transmission fluid filter.
Relief valve failure - Replace relief valve as required.

Transmission is making noise
Transmission oil insufficient - Fill the transmission housing with oil.
Transmission fluid contamination - Change the fluid.
Gears are damaged or backlash is incorrect - Replace defective gears or set backlash properly.
Worn or damaged bearings - Replace faulty bearings.
Worn or bent shift forks - Replace defective shift forks.
Worn or stuck shaft splines - Replace the shaft.

Hard to shift gears
Gear shift linkage is worn or rusty - Lubricate or replace shift linkage.
Shift forks are worn or bent - Shift forks need to be replaced.
Gearshift mechanism malfunction - Identify and replace failed parts.
Malfunction or incorrect clutch adjustment - Clutch adjustment or replacement required.

External fluid leaks
Transmission fluid level is high - Correct the fluid level.
Damaged gaskets or seals - Seals and gaskets need to be replaced.

Hydraulics Troubleshooting

Hydraulic system overheats
Incorrect hydraulic pressure setting - Hydraulic pressure must be set correctly.
Main relief valve is faulty or misadjusted - Adjust relief valve or change if required.
Dirty hydraulic fluid - Change hydraulic fluid.
Hydraulic fluid level is low - Need to add fluid.
Hydraulic pump is defective - Install new pump or repair it.

Lift arm can't drop or lift
Lift controls are defective - Repair or change.
Hydraulic pump malfunction - Install new pump or repair it.
Faulty hydraulic control valve - Repair or replace the valve.
Faulty hydraulic cylinder - Repair or replace hydraulic cylinder.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.

Bucket does not function
Bucket tilt controls are defective - Replace or repair.
Hydraulic pump failure - Repair or install new hydraulic pump.
Defective hydraulic control valve - Replace or repair the valve.
Damaged bucket cylinder - Repair or change cylinder.
Insufficient hydraulic fluid - Fill the system to proper hydraulic fluid level.

Slow boom or bucket operation
Hydraulic pump is faulty - Test the pump performance and change pump if required.
Hydraulic cylinder leaking - Repair leak by replacing the seals.
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Damaged or incorrect adjusted hydraulic control valve - Set correctly or repair.
Hydraulic pressure is low - Adjust pressure as required.

Lift arm or bucket jerks when working
Air in the hydraulic system - Bleed air from system.
Hydraulic oil filter clogging - Clean or install new filter.
Hydraulic fluid is contaminated - Change hydraulic fluid.
Cylinder tube or rod scoring - Replace damaged component.

Hydraulic pump makes excessive noise
Low oil level or hydraulic leaks - Correct hydraulic leaks or top up oil as needed.
Hydraulic filter clogging - Clean or install new filter.
Plugged suction line - Clean suction line as required.
Pump sucks air - Need to bleed air.
Faulty pump components - Replace or rebuild the pump.

Electrical Troubleshooting

Battery won’t charge
Loose or corroded electrical wiring connections - Clean or tighten connections.
Battery terminal clamps are faulty - Terminal clamps should be changed.
Battery faulty cell - Battery change required.
Loose or worn belt - Install a new belt or adjust belt tension.

Starter turns slow
Low battery output - Battery is drained, recharge it.
Battery is draining quickly - Service charging system or install new battery.
Battery terminals are corroded or wires are disconnected - Check cable connections and replace or service terminals.

Starter will not crank
Battery is low or faulty - Recharge or change battery.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Battery power is low - Battery is drained, charge it.
Defective starter motor - Starter should be replaced.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders