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Bobcat 720 Troubleshooting

The Bobcat 720 skid steer loader driveline system components: Wisconsin VF4D 4-cylinder air-cooled gasoline/LPG engine with a rated power of 28 hp (20.9 kW), and 1-speed or 2-speed hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 10 gal/min (37.9 l/min). The system relief pressure is 2100 psi (145 bar). The Bobcat 720 is equipped with a radial-lift loader boom, 80H drive chains, and 7.00x15 standard tires. The skid steer loader has a maximum lift height of 109" (2770 mm) to hinge pin and dump height of 87" (2210 mm). The rated operating capacity is 1200 lbs (544 kg), and tipping load is 2400 lbs (1090 kg).

Engine Troubleshooting

Engine will not start or hard to start
No gasoline in tank - Fill fuel up.
Improper fuel grade - Change fuel.
Dirty fuel lines - Inspect and clean.
Damaged spark plug wiring connection - Check spark plug wiring connection, repair or change.
Spark plug is faulty - Spark plug need to be replaced.
Defective ignition system - Check ignition and replace faulty components.
Fuel filter is clogged - Fuel filter needs changing.
Fuel lines are dirty - Fuel lines need to be cleaned.
Fuel pump is dirty or defective - Inspect fuel pump and change as required.
Problems with carburetor adjustment - Adjust as required.
Engine has bad compression - Check cylinder block and change wear parts.

Unstable engine running
Defective ignition - Inspect ignition system and change failed components.
Dirty air filter element - Clean or change.
Damaged spark plug - Change spark plug.
Fuel pump is dirty or defective - Test fuel pump and change if necessary.
Improper valve clearance - Adjust valve clearance.
Ignition timing is incorrect - Adjust ignition timing as required.
Improperly adjusted low idle speed - Adjust the low idle speed.

Engine starts but stalls immediately
Spark plug is damaged - Install new spark plug.
Carburetor is dirty or defective - Repair or clean carburetor.
Damaged ignition coil - Install a new ignition coil.
Bad or broken valve springs - Valve springs need to be changed.
Stuck valves - Valves must be cleaned.

Engine overheating
Low engine oil level - Fill up the oil to required level.
Engine overloaded - Load reducing required.
Carburetor is running lean - Make the correct settings.
Ignition timing is incorrect - Set the ignition timing properly.
Improper valve setting - Set the valves correctly.
Radiator fins are dirty or radiator cap is defective - Clean radiator or replace cap.
Low coolant level - Add coolant fluid to cooling system and also check it for leaks.
Defective thermostat - Change thermostat as required.
Faulty water pump - Change water pump.

Abnormal engine noise or knocking
Stale or low octane fuel - Change fuel.
Engine is overloaded - Reduce the load.
Engine oil level is insufficient - Add oil to the engine crankcase.
Too low idle RPM - Adjustment required.
Dirty or damaged fuel pump - Service or change fuel pump.
Crankshaft or main bearings wear - Install new parts as as required.
Incorrect valve clearance - Adjustment procedure required.
Worn piston rings or cylinder bore - Change defective parts.

Low engine power
Clogged or improperly adjusted carburetor - Adjust the carburetor properly or clean it.
Clogged air filter - Clean or replace air filter.
Clogged or damaged fuel pump - Test fuel pump and replace if necessary.
Ignition system problems - Check ignition and replace faulty components.
Defective cylinder head gasket - Replace the gasket as required.
Valves are burned or stuck - Service or replace valves.
Worn cylinder block parts - Replace defective components.
Oil filter is blocked - Clean or change oil filter.

High fuel consumption
Plugged air filter - Clean or replace air filter.
Carburetor main jet adjustment is incorrect - Adjust it properly.
Spark plug is faulty or loose - Re-tighten or change the spark plug.
Incorrect ignition timing - Set the ignition timing properly.
Valves are worn, burned or stuck - Service or replace valves.
Piston, sleeve, or rings are damaged - Change defective components.
Valve clearance is improper - Adjust to proper valve clearance.
Engine has bad compression - Check cylinder block and change wear parts.

Engine using too much oil
Damaged gaskets or seals - To repair leaks, replace worn parts.
Valve stems and guides are worn - Replace the valves.
Worn or broken piston rings - Piston rings replacement required.
Cylinder liner or piston is scuffed - Inspect liner and piston, fit new parts as necessary.

Engine backfires
Too lean carburetor mixture - Adjust carburetor properly.
Fuel lines clogging - Fuel lines must be clean.
Incorrect ignition timing - Adjust ignition timing as required.
Valve setting is wrong - Set the valves properly.
Dirty air filter element - Change or clean air filter.

Drive System Troubleshooting

Machine is not moving forward or backward
Insufficient hydraulic oil - Checking hydraulic oil level and add if necessary.
Drive chain malfunction - Check drive chain and change defective components.
Damaged input drive shaft - Repair or install a new drive shaft.
Worn or defective relief valve - Relief valve need to be replaced or repair.
Plugged suction line or hydraulic filter - Check, clean, or change if necessary.
Hand or foot controls malfunction - Check and repair as required.
Worn drive motor or pump - Replace or repair faulty component.

Lack of power
Clogged hydraulic oil filter - Change or service hydraulic filter.
Faulty or opened relief valve - Replace or close relief valve.
Worn or defective transmission parts - Check and replace defective components.
Defective input drive shaft - Repair or replace drive shaft.
Air in hydraulic system - Air bleeding is required.

Drive system overheats
Insufficient hydraulic oil - Check and refill the hydraulic oil.
Plugged hydraulic fluid filter - Replace or clean hydraulic filter.
Faulty relief valve - Repair or replace.
Hydraulic motor or drive pump is worn - Repair or replace faulty component.
Plugged hydraulic oil cooler - Cooling fins should be cleaned.
Transmission overloading - Reduce drive system load.

Drive system is excessively noisy
Improper oil viscosity - Use oil of correct viscosity.
Air trapped in hydraulic system - Bleed hydraulic system.
Hydraulic motor or drive pump is worn - Change or repair faulty component.
Mechanical parts of drive system are worn or damaged - Check the components for worn or defect and replace if necessary.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure is not adjusted correctly - Correct adjustment is required.
Main relief valve is damaged or adjusted improperly - Adjust or replace the relief valve.
Hydraulic oil is contaminated - The oil must be changed.
Not enough hydraulic oil in the system - Fill the hydraulic system with oil.
Worn hydraulic oil pump - Repair or install new hydraulic pump.

Lift arm can't drop or lift
Lift controls malfunction - Change or repair.
Hydraulic pump malfunction - Repair or install new hydraulic pump.
Hydraulic control valve failure - Install a new valve or repair it.
Hydraulic cylinder is faulty - Repair or install a new lift cylinder.
Insufficient hydraulic oil - Need to add oil.

Bucket is not working
Bucket controls failure - Inspect and repair if necessary.
Hydraulic pump is broken - Repair or install new hydraulic pump.
Hydraulic control valve malfunction - Install a new valve or repair it.
Hydraulic bucket cylinder is defective - Repair or change cylinder.
Hydraulic oil level low - Fill the system to proper hydraulic oil level.

Bucket or lift arm runs slowly
Worn hydraulic oil pump - Check the pump capacity and replace pump if required.
Hydraulic cylinder leaking - Cylinder seals need to be replaced.
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Faulty or incorrect setting hydraulic control valve - Repair or adjust properly.
Hydraulic pressure is low - Set pressure correctly.

Lift arm or bucket is jerky
Air in hydraulic system - Air bleeding is required.
Hydraulic oil filter element is dirty - Service or replace the hydraulic filter.
Hydraulic fluid is contaminated - Change hydraulic fluid.
Cylinder tube or rod is scored - Change failed component.

Excessive hydraulic pump noise
Lack of oil or hydraulic leakage - Refill hydraulic oil or repair leaks in system.
Dirty hydraulic filter - Change or clean oil filter.
Dirty suction line - Service the suction line.
Pump sucks air - Bleed air.
Pump parts are faulty - Rebuild or change hydraulic pump.

Electrical Troubleshooting

Battery will not charge
Loose or corroded electrical wiring connections - Tighten or service cable connections.
Battery terminal clamps are faulty - Install new terminal clamps.
Battery is worn - Install a new battery.
Loose or worn belt - Need to adjust belt tension or replace belt.

Starter turning slow
Low battery capacity - Battery is drained, recharge it.
Battery drains quickly - Battery needs to be serviced or replaced.
Bad battery terminals or disconnected wiring - Check cables and service or change terminals.

Starter motor won't turn
Battery is drained or defective - Recharge or change battery.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Low battery voltage - Recharge the battery.
Faulty starter motor - Replace or repair starter.