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

Case 621D Troubleshooting

The Case 621D wheel loader driveline system components: 359 cu.in (5.9L) Case 6BT-590 six-cylinder direct injection turbocharged liquid-cooled diesel engine with a rated power of 134 hp (99.3 kW), and 4-speed powershift transmission with torque converter. The closed center hydraulic system has a piston pump with a rated capacity of 45.2 gal/min (171 l/min). The Case 621D is equipped with a power steering system, hydraulic wet disc brakes, and 20.5x25 tires. The wheel loader has a maximum lift height of 150.7" (3830 mm) and breakout force of 23440 lbs (10635 kg). The rated operating capacity is 8815 lbs (4000 kg), and tipping load is 17630 lbs (8000 kg).

Engine Troubleshooting

Engine hard to start or doesn't start
Air in fuel tank - Bleed fuel tank.
Fuel filter plugging - Service the filter.
Fuel injection nozzles are faulty or clogged - Change fuel injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
Incorrect valve clearance - Adjust to proper valve clearance.
Fuel injection pump is broken - Install a new fuel pump or repair.

Engine starts and then shuts off
Air cleaner is dirty - Clean or change cleaner.
Fuel filter element clogging - Change filter element.
Poor fuel injection pump tightness - Look for any leaks of fuel pump, tighten it fast.
Clogged or defective injectors - Test and replace fuel injectors if necessary.
Fuel injection pump is faulty - Replace or rebuild injection pump.

Engine stops suddenly during operation
Coolant temperature is low - Warm up to required temperature.
Dirty fuel filter - Clean the filter or install new filter element.
Air in fuel tank - Bleed fuel tank.
Fuel injection nozzles are dirty or defective - Test injection nozzles and change if necessary.
Wrong setting of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.

Engine stops when idle
Low idle speed adjustment is incorrect - Adjust low idle speed.
Fuel injection pump malfunction - Rebuild or replace pump.
Defective fuel injectors - Change or clean fuel injectors.
Valve clearance is out of adjustment - Correct valve clearance.

Diesel engine is losing power
Dirty air cleaner - Clean or replace element.
Defective injection nozzle - Service or change injection nozzles.
Incorrect fuel injection pressure - Adjust to correct pressure.
Valve clearance is not correct - Correct valve clearance.
Incorrectly adjusted low idle speed - Adjust low idling as recommended.
Fuel hoses or lines are clogged - Clean fuel hoses and lines.
Cylinder-head gasket is broken - Replace cylinder head gasket.
Piston rings are defective or leaking - Replace piston rings.

Engine overheating
Not enough coolant - Fill the cooling system and check components for leaks or other faults.
Engine oil level is insufficient - Fill up the engine oil.
Clogged radiator fins or leaking radiator cap - Clean radiator or change cap.
Fan belt is broken or worn - If necessary, replace the belt.
Engine is overloaded - Load reducing is recommended.

Low oil pressure
Low oil level - Checking oil level and add if necessary.
Oil filter element clogging - Replace or service engine oil filter.
Incorrect oil viscosity - Fill up with the correct oil viscosity.
Crankshaft bearing has incorrect oil clearance - Install new bearings.
Oil pump is defective - Remove and inspect oil pump.

Abnormal engine knocking or noise
Engine oil level low - Check oil level and add oil as required.
Low coolant temperature - Warm up to required temperature.
Incorrect adjustment of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.
Wrong adjustment of low idle speed - Adjust as required.
Fuel injector fault - Test and replace fuel injectors if necessary.
Misaligned or faulty connecting rod - Align or replace connecting rod.
Pistons are broken or worn - Pistons replacement required.

Transmission Troubleshooting

Low transmission oil pressure
Insufficient transmission fluid - Checking transmission fluid level and add if necessary.
Clogged transmission fluid filter (if equipped) - Service or replace the transmission fluid filter.
Defective relief valve - Change the valve.

Transmission noise
Transmission fluid insufficient - Checking transmission fluid level and add if necessary.
Transmission oil is dirty - Fill up with fresh transmission oil.
Damaged gears or incorrect backlash - Change the gears or set backlash properly.
Worn or damaged bearings - Install new bearings.
Worn or damaged gear shift forks - Change defective shift forks.
Stuck or worn shaft splines - Shaft need to be replaced.

Gear hard to shift
Corroded or worn gear shift linkage - Replace or lubricate the shift linkage.
Worn or bent shift forks - Change defective shift forks.
Worn gear shifting mechanism - Repair or change worn components if necessary.
Worn or improperly adjusted clutch - Clutch adjustment or replacement required.

Transmission oil leaking
High transmission oil level - Correct the oil level.
Damaged gaskets or seals - Replace worn gaskets or seal.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is not adjusted correctly - Correct setting is required.
Faulty or improperly adjusted main relief valve - Adjust the valve or replace if necessary.
Hydraulic fluid is contaminated - Change hydraulic fluid.
Hydraulic oil level is low - Fill up the hydraulic oil.
Hydraulic pump is faulty - Repair or change pump if required.

Boom fails to lift or drop
Lift controls malfunction - Inspect and repair if necessary.
Defective hydraulic pump - Repair or change pump if required.
Hydraulic control valve is defective - Install a new hydraulic valve or repair it.
Broken hydraulic cylinder - Install a new boom cylinder or repair it.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.

Bucket tilt does not work
Bucket tilt controls malfunction - Replace or repair.
Hydraulic pump not working - Change or repair hydraulic pump if required.
Hydraulic control valve is defective - Repair or change the valve.
Bucket cylinder malfunction - Repair or install a new cylinder.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.

Bucket or lift arm moves slowly
Faulty hydraulic oil pump - Check pump capacity and change if necessary.
Hydraulic cylinder oil leakage - Replace cylinder piston seals.
Hydraulic fluid is insufficient - Checking hydraulic fluid level and add if necessary.
Damaged or incorrect adjusted hydraulic control valve - Repair or set properly.
Hydraulic system loosing pressure - Correct adjustment is required.

Jerky operation of the bucket or boom
There is air in the hydraulic system - Need to bleed air.
Hydraulic oil filter is dirty - Service or change the hydraulic filter.
Hydraulic fluid contamination - The fluid must be changed.
Scored cylinder tube or rod - Replace worn component.

Hydraulic pump is noisy
Hydraulic leaks or lack of oil - Correct hydraulic leaks or top up oil as needed.
Plugged hydraulic filter - Service or change hydraulic filter.
Plugged suction line - Suction line must be serviced.
Air in hydraulic pump - Air bleeding is required.
Pump parts are faulty - Rebuild or install new pump.

Electrical Troubleshooting

Battery does not charge
Corroded or loose electrical wire connections - Clean or tighten connections.
Battery terminal clamps are faulty - Install new terminal clamps.
Battery dead cell - Change the battery.
Belt is worn or loose - Adjust belt tension or change the belt.

Starter turns slowly
Low battery voltage - Battery is drained, recharge it.
Battery will not hold charge - Battery needs to be serviced or replaced.
Wires are disconnected or battery terminals are corroded - Check battery wires and service or replace terminals.

Starter will not crank
Battery is discharged or worn - Need to charge or replace the battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery power - Battery needs to be recharged.
Starter motor is faulty - Starter needs to be replaced.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders