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Bobcat 743 Troubleshooting

The Bobcat 743 skid steer loader driveline system components: a 105.7 cu.in (1.7L) Kubota V1702-BA 4-cylinder water-cooled diesel engine with a rated power of 36 hp (26.8 kW), and single-speed hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 11 gal/min (41.6 l/min). The system relief pressure is 2400 psi (165 bar). The Bobcat 743 is equipped with a radial-lift loader boom, 80HS drive chains, and 7.00x15 standard tires. The skid steer loader has a max lift height of 109" (2770 mm) to hinge pin and dump height of 86.3" (2190 mm). The rated operating capacity is 1300 lbs (590 kg), and tipping load is 2600 lbs (1180 kg).

Engine Troubleshooting

Engine hard to start or doesn't start
Air in fuel system - Bleed fuel system.
Fuel filter plugging - Filter maintenance required.
Fuel injection nozzles are dirty or defective - Check injection nozzles and replace if required.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve clearance is wrong - Adjust to proper valve clearance.
Fuel injection pump is defective - Rebuild or install a new injection pump.

Diesel starts and then shuts off
Dirty air cleaner - Clean or change cleaner.
Fuel filter plugging - Change filter element.
Fuel injection pump has loose connections - Tighten the connections.
Fuel injectors are dirty or defective - Test and replace fuel injectors if necessary.
Defective fuel injection pump - Repair or install new pump.

Engine stalls after running
Engine is not preheated - Warm up engine as required.
Fuel filter element clogging - Replace the filter element.
Air in fuel system - Bleed fuel system.
Clogged or burnt injection nozzle - Replace injection nozzles.
Wrong setting of fuel injection pump timing - Adjust the pump as required.

Engine stops when idle
Incorrect low idle speed adjustment - Adjust low idling as recommended.
Faulty fuel injection pump - Install a new fuel pump or repair.
Fuel injectors are dirty or defective - Clean or replace fuel injectors.
Valve clearance is not correct - Have it adjusted.

Diesel engine loses power
Air filter is dirty - Clean or replace element.
Fuel injection nozzles are damaged or dirty - Check injection nozzles and replace if required.
Incorrect fuel injection pressure - Adjust to proper pressure.
Improper valve clearance - Adjustment procedure required.
Low idle speed setting is not correct - Need to adjust idle speed.
Dirty fuel hoses or lines - Clean fuel system lines and hoses.
Cylinder head gasket is blown - Cylinder-head gasket replacement required.
Leaking or defective piston rings - Change piston rings.

Engine overheats
Lack of engine coolant - Fill radiator to proper level and check components for faults.
Engine oil level low - Check oil level and add oil as required.
Defective radiator cap or clogged radiator core - Clean radiator or install new cap.
Fan belt is broken or worn - Install new fan belt.
Diesel engine is overloaded - Load reducing required.

Low oil pressure
Engine oil insufficient - Check oil level and add oil as required.
Dirty oil filter - Replace or clean engine oil filter element.
Oil grade or viscosity is incorrect - Fill up with the correct oil viscosity.
Excessive oil clearance of crankshaft bearing - Change bearings.
Oil pump failure - Replace as required.

Engine knocking or noise
Insufficient engine oil - Checking oil level and add if necessary.
Engine is not warmed up to the required temperature - Warm up engine as required.
Wrong setting of fuel injection pump timing - Adjust the pump as required.
Incorrect low idle setting - Adjust as required.
Dirty or defective injectors - Test and replace fuel injectors if necessary.
Connecting rod is worn or misaligned - Connecting rod needs to be replaced or aligned.
Scored or worn pistons - Replace the pistons as required.

Drive System Troubleshooting

Drive system сan't work in either direction
Hydraulic oil level is low - Need to add oil.
Drive chain failure - Check drive chain and change defective components.
Faulty relief valve - Change or repair defective relief valve.
Hydraulic filter or suction line is plugged - Check, clean, or replace if required.
Defective or worn foot or hand controls - Replace or repair.
Defective drive pump or motor - Replace or repair faulty component.

Reduced power
Clogged hydraulic oil filter - Replace hydraulic filter.
Defective or open relief valve - Replace or close relief valve.
Worn or faulty transmission components - Inspect and change faulty parts.
Defective input drive shaft - Faulty drive shaft need to be replaced or repair.
Air leaks in hydraulic system - Bleed air from hydraulic system.

Overheated drive system
Low hydraulic oil level - Need to add oil.
Clogged hydraulic fluid filter - Replace or service hydraulic filter.
Worn or damaged relief valve - Change or repair relief valve.
Defective drive pump or hydraulic motor - Inspect and replace as necessary.
Clogged hydraulic oil cooler - Cooling fins should be cleaned.
Drive system overloaded continuously - Reduce the load.

Excessive noise
Wrong oil viscosity - Use proper oil viscosity.
Air leaks in hydraulic system - Bleed air from hydraulic system.
Drive pump or hydraulic motor malfunction - Inspect and change as required.
Worn or damaged mechanical parts of drive system - Inspect the components for worn or defect and repair as required.

Hydraulics Troubleshooting

Hydraulic system has overheating
Incorrect hydraulic pressure setting - Adjust pressure as required.
Defective or misadjusted main relief valve - Adjust or replace the relief valve.
Dirty hydraulic fluid - Fill up with fresh hydraulic fluid.
Not enough hydraulic fluid in the system - Add fluid to the hydraulic system.
Worn hydraulic oil pump - Replace or repair pump if necessary.

Lift arm cannot be raised or lowered
Damaged lift controls - Repair or change.
Hydraulic pump not working - Repair or replace pump if necessary.
Hydraulic control valve is faulty - Repair or change hydraulic valve.
Hydraulic cylinder not working - Replace or repair boom cylinder.
Hydraulic fluid is insufficient - Add fluid as required.

Bucket is not working
Bucket tilt controls malfunction - Change or repair.
Hydraulic pump failure - Repair or change pump if required.
Hydraulic control valve is faulty - Repair or replace hydraulic valve.
Bucket cylinder is faulty - Change or repair cylinder.
Low hydraulic oil level - Need to add oil.

Boom or bucket runs slowly
Hydraulic pump is faulty - Test the pump flow rate and install new pump if required.
Hydraulic cylinder leaking - Install new cylinder seals.
Low hydraulic oil level - Checking hydraulic oil level and add if necessary.
Damaged or incorrect adjusted hydraulic control valve - Adjust correctly or repair.
Hydraulic pressure has dropped - Correct adjustment is required.

Bucket or boom is jerky
Air in hydraulic system - Air bleeding is required.
Hydraulic oil filter element is dirty - Service or replace the hydraulic filter.
Hydraulic oil is dirty - Fill up with fresh hydraulic oil.
Scored cylinder tube or rod - Change failed component.

Hydraulic pump makes excessive noise
Hydraulic leakage or lack of oil - Refill hydraulic oil or repair leaks in system.
Hydraulic filter is clogged - Clean or change the filter.
Plugged suction line - Need to service the suction line.
Air in hydraulic pump - Air bleeding is required.
Damaged pump parts - Rebuild or install new pump.

Electrical Troubleshooting

Battery cannot be charged
Loose or corroded electrical wiring connections - Clean or tighten connections.
Battery terminal clamps are defective - Terminal clamps need to be replaced.
Worn-out battery - Change the battery.
Damaged or loose belt - Install a new belt or adjust belt tension.

Starter motor turns slow
Battery capacity is low - Battery is drained, charge it.
Battery is not holding charge - Service battery or replace it.
Disconnected wires or corroded battery terminals - Check wiring and clean or replace terminals.

Starter motor won't turn
Battery is drained or worn - Need to charge or replace the battery.
Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly.
Low battery output voltage - Battery is drained, recharge it.
Faulty starter motor - Repair or change starter.