• All Manufacturers

  • Bobcat
  • Case
  • Caterpillar
  • Doosan
  • John Deere
  • Kubota

  Wheel Loaders

  • Bobcat L28
  • Cat 926M
  • Case 221D
  • John Deere 304H
  • Doosan DL280-7
  • Case 521E
  • Kubota R070
  • John Deere 624J

Home / Wheel Loaders / Case Wheel Loaders / Case 621C

Case 621C Troubleshooting

The Case 621C wheel loader is powered by 359 cu.in (5.9L) Case 6T-590 6-cylinder direct injection turbocharged liquid-cooled diesel engine with a rated power of 130 hp (97 kW) at 2200 rpm. The Case 621C is equipped with a 4x3 powershift transmission, power steering system, hydraulic wet disc brakes, and 20.5x25 or 555/70R25 tires. The open center hydraulic system has a pump with fluid flow rate of 42.9 gpm (163 lpm). The wheel loader has a rated operating capacity of 8726 lbs (3958 kg) and tipping load of 17450 lbs (7915 kg). The maximum lift height is 145.5" (3695 mm) to hinge pin, and bucket breakout force is 28680 lbs (13010 kg).

Engine Troubleshooting

Engine difficult to start or doesn't start
Air in the fuel system - Air bleeding.
Fuel filter element is dirty - Filter maintenance required.
Defective or clogged injection nozzle - Inspect nozzles and replace if necessary.
Water or dirt in fuel system - Drain, flush, and service the system.
Excessive valve clearance - Check and adjust.
Faulty fuel injection pump - Rebuild or replace pump.

Engine starts but stalls suddenly
Dirty air filter - Clean or change.
Fuel filter element is dirty - Replace filter element.
Fuel injection pump is leaking - Repair any leaks.
Damaged or clogged injectors - Change or clean fuel injectors.
Fuel injection pump malfunction - Repair or replace injection pump.

Engine stops suddenly during operation
Low coolant temperature - Warm up to required temperature.
Dirty fuel filter - Change the filter element.
Air in the fuel lines - Bleed the fuel lines.
Fuel injection nozzles fault - Change fuel injection nozzles.
Fuel injection pump timing is wrong - Adjust according to specifications.

Engine stalls while idle
Low idle speed set incorrectly - Adjustment required.
Fuel injection pump is faulty - Rebuild or replace pump.
Fuel injectors are dirty or defective - Replace or clean fuel injectors.
The valve clearance is incorrect - Adjust valve clearance.

Engine power is insufficient
Air filter is clogged - Clean or change filter.
Fuel injection nozzles fault - Replace injection nozzles.
Uneven fuel injection pressure - Test fuel injection pressure and adjust it correctly.
The valve clearance is incorrect - Check and adjust.
Incorrect low idle speed adjustment - Test and adjust.
Fuel hoses or lines clogging - Fuel lines and hoses need to be cleaned.
Blown cylinder head gasket - Install new cylinder head gasket.
Piston rings are worn or defective - Piston rings need to be replaced.

Engine overheats
Not enough coolant - The cooling system needs to be refilled and checked for faults.
Engine oil level is low - Check and refill engine oil.
Clogged radiator fins or damaged radiator cap - Clean radiator or change cap.
Fan belt slipping or worn - Change as required.
Engine is under excessive load - Load reducing is recommended.

Oil pressure is low
Not enough oil in the engine - Need to add oil.
Oil filter is dirty - Replace or clean engine oil filter element.
Improper type of engine oil - Fill up with the proper oil viscosity.
Excessive main bearing oil clearance - Bearing replacement required.
Oil pump failure - Repair or replace.

Abnormal engine knocking or noise
Not enough engine oil - Fill the crankcase with engine oil.
Coolant temperature is low - Warm up the engine.
Timing of fuel injection pump is incorrect - Use the correct fuel injection pump timing adjustment.
Too low idle RPM - Correct low idle adjustment.
Fuel injector fault - Clean or replace fuel injectors.
Faulty or misaligned connecting rod - Connecting rod needs to be aligned or changed.
Piston wear or scoring - Replace the pistons.

Transmission Troubleshooting

Low transmission pressure
Low fluid level - Check and refill the transmission fluid.
Transmission fluid filter element is clogged (if equipped) - Service or replace the transmission fluid filter.
Defective relief valve - Install a new relief valve.

Transmission is making noise
Insufficient transmission oil - Check transmission oil level and add oil as required.
Transmission fluid contamination - Transmission fluid change required.
Worn gears or incorrect backlash - Change worn gears or adjust backlash correctly.
Bearings are cracked or worn - Faulty bearings should be changed.
Worn or bent gear shift forks - Replace defective shift forks.
Worn or stuck shaft splines - Change defective shaft.

Gear hard to shift
Gear shift linkage is worn or rusty - Lubricate or replace shift linkage.
Shift forks are bent or worn out - Shift forks need to be changed.
Gearshift mechanism malfunction - Identify and replace failed parts.
Improperly adjusted or worn clutch - Replace or adjust clutch.

Transmission fluid leakage
Too much oil in transmission - Drain the excess oil.
Worn seals or gaskets - Gaskets or seal replacement required.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure is not correct - Adjust it correctly.
Unadjusted or defective main relief valve - Replace or set up the relief valve.
Hydraulic fluid is dirty - Hydraulic fluid change required.
Hydraulic fluid level is low - Check and refill the hydraulic fluid.
Hydraulic pump is worn - Replace or repair pump if necessary.

Lift arm cannot be raised or lowered
Lift controls failure - Check and repair as required.
Defective hydraulic pump - Install new pump or repair it.
Damaged hydraulic control valve - Replace or repair the valve.
Damaged hydraulic cylinder - Repair or install a new lift cylinder.
Insufficient hydraulic oil - Need to add oil.

Bucket can't tilt
Damaged bucket controls - Repair or change.
Hydraulic pump is broken - Repair or replace pump if necessary.
Defective hydraulic control valve - Install a new hydraulic valve or repair it.
Faulty hydraulic bucket cylinder - Repair or change cylinder.
Hydraulic oil level low - Check and refill the hydraulic oil.

Boom or bucket is moving slowly
Hydraulic pump is worn - Test the pump flow rate and install new pump if required.
Hydraulic cylinder leaking - Install new cylinder seals.
Hydraulic oil level low - Fill the system to proper hydraulic oil level.
Worn or unadjusted hydraulic control valve - Repair or adjust properly.
Hydraulic pressure loss - Correct setting is required.

Lift arm or bucket is working jerkily
Air in the hydraulic system - Bleed hydraulic system.
Clogged hydraulic oil filter element - Service or replace the hydraulic filter.
Dirty hydraulic oil - Hydraulic oil change required.
Scratched cylinder rod or tube - Change defective component.

Excessive hydraulic pump noise
Hydraulic leaks or lack of oil - Repair hydraulic leaks or add oil as required.
Hydraulic filter is clogged - Clean or install new filter.
Suction line is clogged - Need to service the suction line.
Pump sucks air - Remove air from hydraulics.
Pump parts are worn out - Rebuild or change hydraulic pump.

Electrical Troubleshooting

Battery cannot be charged
Loose or corroded cable connections - Tighten or clean connections.
Battery terminal connectors are defective - Terminal connectors need to be changed.
Battery is worn - Replace the battery.
Belt is worn or loose - Adjust belt tension or change the belt.

Starter cranks slowly
Low battery voltage - Recharge the battery.
Battery runs out quickly - Service or change the battery.
Battery terminals are corroded or wires are disconnected - Check wiring and clean or replace terminals.

Starter is not working
Battery is low or faulty - Need to charge or replace the battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery voltage - Charge the battery.
Starter motor failing - Starter needs to be changed.

____________________________________________________________________________________

WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders