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Bobcat 743B Troubleshooting

The Bobcat 743B skid steer loader is powered by Kubota V1702-BA 4-cylinder indirect injection liquid-cooled diesel engine with a rated power of 36 hp (26.8 kW) at 2800 rpm. The Bobcat 743B is equipped with a radial-lift loader boom, one-speed hydrostatic transmission, 80HS drive chains, and 10.00x16.5 standard tires. The hydraulic system has a pump with fluid flow rate of 11 gpm (41.6 lpm). The hydraulic pressure is 2400 psi (165 bar). The skid steer loader has a rated operating capacity of 1300 lbs (590 kg) and tipping load of 2600 lbs (1180 kg). The maximum lift height is 109 inches (2770 mm) to hinge pin, and dump height is 86.3 inches (2190 mm).

Engine Troubleshooting

Engine starts hard or won't start
Air in fuel system - Bleed fuel system.
Fuel filter element is dirty - Clean the filter or install new filter element.
Fuel injection nozzles are clogged or faulty - Install a new kit of correctly balanced nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve out of adjustment - Adjustment procedure required.
Fuel injection pump malfunction - Repair or change injection pump.

Diesel starts but immediately stops
Dirty air filter - Service or replace the air filter.
Fuel filter element is clogged - Replace filter element.
Fuel injection pump is leaking - Repair any leaks.
Fuel injectors are faulty or clogged - Clean fuel injectors or change it.
Fuel injection pump malfunction - Rebuild or replace pump.

Engine stops unexpectedly during operation
Low coolant temperature - Warm up engine as required.
Clogged fuel filter - Install new filter element.
Air in fuel system - Bleed fuel system.
Fuel injection nozzles fault - Service or change injection nozzles.
Incorrect adjustment of fuel injection pump timing - Adjust as recommended.

Engine stalls when idle
Wrong adjustment of low idle speed - Correct low idle adjustment.
Fuel injection pump is damaged - Replace injection pump or repair it.
Fuel injector fault - Inspect fuel injectors and change as required.
Incorrect valve clearance - Adjustment procedure required.

Diesel power loss
Plugged air cleaner - Clean or change cleaner.
Clogged or defective injection nozzles - Test injection nozzles and change if necessary.
Incorrect fuel injection pressure - Correct the pressure settings.
Incorrect valve clearance - Adjust to proper valve clearance.
Incorrectly set low idle speed - Adjustment required.
Fuel hoses or lines are clogged - Clean fuel lines and hoses.
Defective cylinder head gasket - Replace the gasket as required.
Damaged or leaking piston rings - Piston rings replacement required.

Engine overheats
Low coolant level - Add coolant fluid and inspect the cooling system for leaks.
Engine oil level is low - Fill up the oil to required level.
Faulty radiator cap or dirty radiator fins - Change cap or clean radiator.
Fan belt slipping or worn - If necessary, replace the belt.
Engine overloaded - Load reducing is recommended.

Oil pressure too low
Oil level is insufficient - Check and refill the oil.
Dirty oil filter - Service or replace engine oil filter.
Incorrect engine oil Fill up with the proper oil viscosity.
Incorrect crankshaft bearing oil clearance - Bearing needs to be changed.
Oil pump is worn or damaged - Remove and inspect oil pump.

Engine knocking sound or abnormal noise
Engine oil level is low - Add oil to the engine crankcase.
Engine is not preheated - Warm up to required temperature.
Incorrect adjustment of fuel injection pump timing - Adjust the pump as required.
Improperly adjusted low idle speed - Correct low idle settings.
Dirty or defective injectors - Clean fuel injectors or change it.
Connecting rod is worn or not aligned - Need to align or replace the connecting rod.
Pistons are scored or worn - Install new pistons.

Drive System Troubleshooting

Machine does not move forward or backward
Hydraulic fluid is insufficient - Fill up the hydraulic fluid.
Drive chain is worn - Check drive chain and change faulty components.
Relief valver is broken - Change or repair relief valve.
Dirty hydraulic filter or suction line - Check, clean, or change if necessary.
Defective or worn foot or hand controls - Repair or replace.
Defective drive pump or motor - Change or repair faulty component.

Low power
Hydraulic oil filter is dirty - Change hydraulic filter.
Open or faulty relief valve - Replace or close relief valve.
Transmission parts are faulty or damaged - Check and replace defective components.
Defective input drive shaft - Replace or service the drive shaft.
Air trapped in hydraulic system - Bleed hydraulic system.

Overheated drive system
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Hydraulic fluid filter is plugged - Replace or service hydraulic filter.
Relief valve malfunction - Repair or install a new relief valve.
Worn hydraulic motor or drive pump - Inspect and change as required.
Hydraulic oil cooler is plugged - Cooling fins need to be cleaned.
Drive system is overloaded - Load needs to be reduced.

Drive system makes excessive noise
Wrong oil viscosity - Drain and refill with proper oil.
Hydraulic system is leaking air - Bleed air from hydraulic system.
Hydraulic motor or drive pump failure - Repair or change faulty component.
Worn or defective mechanical components of drive system - Inspect drive system and replace faulty components.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure incorrectly adjusted - Correct adjustment is required.
Main relief valve is faulty or misadjusted - Adjust or replace the relief valve.
Hydraulic fluid contamination - Hydraulic fluid change required.
Hydraulic fluid level is low - Check and refill the hydraulic fluid.
Hydraulic pump is faulty - Repair or replace pump if necessary.

Boom does not raise or lower
Lift controls are faulty - Repair or replace.
Hydraulic pump failure - Repair or replace pump if necessary.
Faulty hydraulic control valve - Repair or change hydraulic valve.
Broken hydraulic cylinder - Change or repair lift cylinder.
Hydraulic oil level low - Check and refill the hydraulic oil.

Bucket does not function
Bucket tilt controls are damaged - Inspect and repair if necessary.
Defective hydraulic pump - Install new pump or repair it.
Hydraulic control valve is faulty - Repair or replace hydraulic valve.
Hydraulic bucket cylinder not working - Repair or change cylinder.
Low hydraulic oil level - Need to add oil.

Bucket or lift arm runs slowly
Worn hydraulic oil pump - Flow-rate pump and change pump if necessary.
Hydraulic cylinder oil leakage - Correct leakage by changing the seals.
Hydraulic oil is insufficient - Need to add oil.
Hydraulic control valve is not set properly or defective - Repair or set properly.
Hydraulic pressure is low - Adjust it correctly.

Lift arm or bucket is working jerkily
Air leaks in hydraulic system - Need to bleed air.
Hydraulic oil filter is clogged - Service or change the hydraulic filter.
Contaminated hydraulic fluid - Fill up with fresh hydraulic fluid.
Cylinder rod or tube is scratched - Change damaged component.

Hydraulic pump makes excessive noise
Low oil level or hydraulic leaks - Remedy hydraulic leakage or refill oil as necessary.
Plugged hydraulic filter - Clean or change the filter.
Suction line clogging - Clean suction line as required.
Pump sucks air - Air bleeding is required.
Faulty pump parts - Install new hydraulic pump or rebuild it.

Electrical Troubleshooting

Battery cannot be charged
Loose or corroded electrical wiring connections - Clean or tighten wiring connections.
Faulty battery terminal connectors - Replace terminal connectors.
Battery faulty cell - Battery change required.
Damaged or loose belt - Adjust belt tension or change the belt.

Starter turning slow
Battery power is low - Recharge the battery.
Battery will not hold charge - Service charging system or change battery.
Disconnected battery cables or bad terminals - Check wiring and clean or replace terminals.

Starter will not crank
Battery is discharged or worn - Need to charge or replace the battery.
Battery wiring is disconnected or improperly connected - Inspect wiring and connect as required.
Battery voltage is low - Charge the battery.
Starter motor failing - Repair or replace starter.