____________________________________________________________________________________
| Home / Skid Steer Loaders / Bobcat Skid Steer Loaders / Bobcat 721 |
Bobcat 721 Troubleshooting
The
Clark Bobcat 721 skid steer loader is powered by 85.2 cu.in (1.4L) Deutz F2L411
two-cylinder liquid-cooled diesel engine with a rated power of 27.5 hp (20.5 kW)
at 2700 rpm. The Clark Bobcat 721 is equipped with a radial-lift loader boom,
one-speed or two-speed hydrostatic transmission, 80H drive chains, and 7.00x15
tires. The hydraulic system has a pump with fluid flow rate of 10 gpm (37.9
lpm). The hydraulic pressure is 2100 psi (145 bar). The skid steer loader has a
rated operating capacity of 1275 lbs (580 kg) and tipping load of 2550 lbs (1160
kg). The lift height is 109 inches (2770 mm) to hinge pin, and dump height is 86
inches (2185 mm).
| Engine Troubleshooting |
Engine starts hard or doesn't start
Air trapped in fuel system - Bleed air.
Dirty fuel filter - Change the filter element.
Burnt or clogged injection nozzle - Service or change injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
The valve clearance is not adjusted - Adjust valve clearance.
Faulty fuel injection pump - Rebuild or replace pump.
Diesel starts but stalls immediately
Plugged air filter - Clean or replace element.
Fuel filter element is clogged - Clean or change the filter.
Fuel injection pump is leaking - Repair any leaks.
Clogged or defective injectors - Clean fuel injectors or change it.
Fuel injection pump damage - Rebuild or change fuel pump.
Diesel shuts off while driving
Engine is not preheated - Warm up engine as required.
Fuel filter element is clogged - Replace filter element.
Air trapped in fuel system - Bleed air.
Faulty or dirty injection nozzles - Check injection nozzles and replace if required.
Timing of fuel injection pump is incorrect - Set it up as required.
Engine stalls while idle
Incorrectly set low idle speed - Test and adjust.
Damaged fuel injection pump - Replace injection pump or repair it.
Defective fuel injectors - Clean fuel injectors or change it.
Valve clearance is not correct - Check and adjust.
Diesel power loss
Dirty air cleaner - Clean or replace air cleaner element.
Clogged injection nozzle - Test injection nozzles and change if necessary.
Fuel injection pressure is incorrect - Correct the pressure settings.
Incorrect valve clearance - Check and adjust.
Low idle speed adjustment is incorrect - Adjust low idle speed.
Fuel lines or hoses are clogged - Service fuel hoses and lines.
Cylinder-head gasket is leaking - Install a new gasket.
Worn or broken piston rings - Change piston rings.
Engine overheating
Engine has a lack of coolant - Add coolant and check the components of cooling system.
Engine oil insufficient - Need to add engine oil.
Clogged radiator core or leaking radiator cap - Clean radiator or change cap.
Loose or defective fan belt - Change as required.
Engine overloaded - Load reducing is recommended.
Oil pressure is insufficient
Oil level is low - Fill up the engine oil.
Oil filter element clogging - Clean or change engine oil filter.
Improper type of engine oil - Use proper viscosity oil.
Crankshaft bearing oil clearance is incorrect - Replace bearings.
Defective oil pump - Replace as required.
Engine knocking or noise
Engine oil level low - Checking oil level and add if necessary.
Coolant temperature is low - Warm up engine as required.
Fuel injection pump timing is not adjusted - Use the correct fuel injection pump timing adjustment.
Low idle speed set incorrectly - Normalize low idle speed.
Fuel injector fault - Replace fuel injectors.
Connecting rod is misaligned or defective - Alignment procedure or replacement is required.
Pistons are scored or worn - Have pistons replaced.
| Drive System Troubleshooting |
Machine is not moving forward or backward
Insufficient hydraulic fluid - Fill the system to proper hydraulic fluid level.
Drive chain malfunction - Inspect drive chain and replace defective components.
Relief valve is stuck - Service or change relief valve.
Suction line or hydraulic filter is clogged - Check, clean, or change if necessary.
Faulty foot or hand controls - Change or repair.
Drive pump or motor is damaged - Replace or repair faulty component.
Power is too low
Clogged hydraulic oil filter - Replace hydraulic filter.
Relief valve is open or defective - Close or replace relief valve.
Worn or defective transmission parts - Check and replace defective components.
Input drive shaft failure - Repair or install a new drive shaft.
Hydraulic system is leaking air - Bleed hydraulic system.
Drive system overheating
Hydraulic oil is insufficient - Checking hydraulic oil level and add if necessary.
Hydraulic fluid filter is plugged - Check, clean, or change as necessary.
Relief valve is worn or damaged - Change or repair relief valve.
Worn hydraulic motor or drive pump - Inspect and replace as necessary.
Plugged hydraulic oil cooler - Clean cooling fins as required.
Overloaded drive system - Reduce loading.
Drive system makes excessive noise
Wrong oil viscosity - Drain and refill with proper oil.
Air in the hydraulic system - Need to bleed air.
Defective drive pump or hydraulic motor - Replace or repair faulty component.
Mechanical components of drive system are defective or worn - Check the parts for defect or damage and change if required.
| Hydraulics Troubleshooting |
Hydraulic system has overheating
Hydraulic pressure is incorrect - Correct setting is required.
Main relief valve is damaged or adjusted improperly - Adjust or change relief valve.
Hydraulic fluid is contaminated - Hydraulic fluid change required.
Lack of hydraulic fluid - Check and refill the hydraulic fluid.
Hydraulic pump is defective - Replace or repair pump if necessary.
Boom cannot be lowered or raised
Lift controls malfunction - Repair or replace.
Hydraulic pump failure - Repair or change pump if required.
Hydraulic control valve is defective - Install a new valve or repair it.
Broken hydraulic cylinder - Install a new boom cylinder or repair it.
Low hydraulic fluid level - Fill up the hydraulic fluid.
Bucket tilt does not work
Damaged bucket controls - Check and repair as required.
Hydraulic pump malfunction - Repair or change pump if required.
Damaged hydraulic control valve - Change or repair hydraulic valve.
Bucket cylinder malfunction - Install a new cylinder or repair it.
Hydraulic oil level low - Checking hydraulic oil level and add if necessary.
Slow boom or bucket action
Hydraulic pump is defective - Check the pump performance and replace it if required.
Hydraulic cylinder oil leakage - Cylinder seals need to be replaced.
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Hydraulic control valve is unadjusted or worn - Adjust correctly or repair.
Hydraulic pressure loss - Set pressure correctly.
Lift arm or bucket movements are jerky
Air leaks in hydraulic system - Need to bleed air.
Dirty hydraulic oil filter element - Clean or change the filter.
Hydraulic oil is contaminated - Hydraulic oil change required.
Cylinder rod or tube is scuffed - Replace defective component.
Hydraulic pump is noisy
Hydraulic leakage or lack of oil - Remedy hydraulic leakage or refill oil as necessary.
Dirty hydraulic filter - Service or replace hydraulic filter.
Clogged suction line - Suction line must be serviced.
Air in hydraulic pump - Bleed air.
Pump parts are damaged - Replace or rebuild the pump.
| Electrical Troubleshooting |
Battery does not charge
Electrical cable connections are loose or corroded - Clean or tighten wiring connections.
Battery terminal connectors are faulty - Install new terminal connectors.
Battery faulty cell - Install a new battery.
Defective or loose belt - Replace belt or adjust belt tension.
Starter motor turns slow
Low battery power - Battery is drained, recharge it.
Battery won’t hold charge - Service battery or change it.
Bad battery terminals or disconnected wiring - Check battery wires and service or replace terminals.
Starter doesn't crank
Battery is drained or worn - Recharge or replace battery.
Battery wiring is disconnected or improperly connected - Inspect wiring and connect as required.
Low battery output voltage - Charge the battery.
Starter motor failing - Starter needs to be changed.
____________________________________________________________________________________
____________________________________________________________________________________
| SKID STEER LOADERS SPECIFICATIONS |