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Bobcat 843B Troubleshooting

The Bobcat 843B skid steer loader driveline system components: a 169 cu.in (2.8L) Isuzu 4JB1-PK01 4-cylinder liquid-cooled diesel engine with a rated power of 54 hp (40.3 kW), and 1-speed hydro transmission. The hydraulic system has a pump with a rated capacity of 16.2 gal/min (61.3 l/min). The system relief pressure is 2400 psi (165 bar). The Bobcat 843B is equipped with a radial-lift loader boom, 100H drive chains, and 8.25x15 standard tires. The skid steer loader has a max lift height of 119.6" (3035 mm) to hinge pin and dump height of 94.5" (2400 mm). The rated operating capacity is 1700 lbs (772 kg), and tipping load is 3400 lbs (1545 kg).

Engine Troubleshooting

Engine starts up hard or doesn't start
Air in fuel tank - Bleed fuel tank.
Dirty fuel filter - Filter maintenance required.
Fuel injection nozzles are damaged or dirty - Replace injection nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Improper valve clearance - Check and adjust as required.
Fuel injection pump is not working correctly - Rebuild or replace pump.

Engine starts but then stops
Air cleaner is clogged - Clean or change cleaner.
Clogged fuel filter - Replace filter element.
Fuel injection pump has loose connections - Tighten the connections.
Clogged or defective injectors - Inspect fuel injectors and change as required.
Fuel injection pump is broken - Rebuild or replace pump.

Engine stops suddenly during operation
Engine is not fully warmed up - Warm up the engine.
Fuel filter element clogging - Change filter element.
Air in the fuel system - Air bleeding.
Fuel injection nozzles are faulty or clogged - Change fuel injection nozzles.
Timing of fuel injection pump is incorrect - Set it up as required.

Engine stalls while idle
Wrong adjustment of low idle speed - Correct low idle adjustment.
Fuel injection pump failure - Install a new fuel pump or repair.
Clogged or defective injectors - Inspect fuel injectors and change as required.
Valve clearance is out of adjustment - Adjust valve clearance according to specifications.

Engine power loss
Air filter is dirty - Replace or clean air filter element.
Faulty fuel injection nozzles - Change fuel injection nozzles.
Incorrect fuel injection pressure - Test fuel injection pressure and adjust it correctly.
Valve clearance is out of adjustment - Correct valve clearance needs to be set.
Low idle speed setting is incorrect - Correct low idle adjustment.
Fuel hoses or lines clogging - Clean fuel hoses and lines.
Cylinder head gasket is worn - Cylinder-head gasket replacement required.
Piston rings are broken or leaking - Replace the piston rings as required.

Engine overheats
Not enough coolant - Add coolant and check the components of cooling system.
Lack of engine oil - Check oil level and add oil as required.
Dirty radiator core or faulty radiator cap - Replace cap or clean radiator.
Fan belt is worn or faulty - The fan belt needs to be replaced.
Engine overloaded - Load reducing is recommended.

Insufficient oil pressure
Insufficient engine oil - Add oil as required.
Clogged oil filter - Replace or clean engine oil filter element.
Improper type of engine oil - Use correct viscosity oil.
Crankshaft bearing has incorrect oil clearance - Replace bearings.
Oil pump malfunction - Repair or change.

Engine noise or knocking
Not enough engine oil - Need to add engine oil.
Engine is not fully warmed up - Warm up to required temperature.
Timing of fuel injection pump is incorrect - Adjust as recommended.
Wrong adjustment of low idle speed - Adjustment required.
Defective fuel injectors - Test and replace fuel injectors if necessary.
Connecting rod is defective or not aligned - Connecting rod needs to be replaced or aligned.
Pistons are broken or worn - Pistons replacement required.

Drive System Troubleshooting

Drive system doesn't operate in one direction or either direction
Low hydraulic oil level - Check and refill the hydraulic oil.
Drive chain failure - Inspect drive chain and replace defective parts.
Faulty relief valve - Relief valve need to be replaced or repair.
Clogged suction line or hydraulic filter - Check, clean, or change if necessary.
Hand or foot controls failure - Check and repair as required.
Drive pump or motor is damaged - Repair or replace faulty component.

Low power
Plugged hydraulic oil filter - Replace or clean hydraulic filter.
Opened or defective relief valve - Replace or close relief valve.
Transmission components are faulty or damaged - Inspect and change defective parts.
Stuck input drive shaft - Rebuild or change the shaft.
Air trapped in hydraulic system - Bleed hydraulic system.

Drive system overheating
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.
Plugged hydraulic fluid filter - Change hydraulic filter.
Relief valve malfunction - Repair or install a new relief valve.
Hydraulic motor or drive pump failure - Replace or repair faulty component.
Hydraulic oil cooler is dirty - Clean cooling fins as required.
Transmission overloading - Reduce loading.

Excessive noise
Improper oil viscosity - Use proper oil viscosity.
Air leaks in hydraulic system - Need to bleed air.
Hydraulic motor or drive pump failure - Change or repair faulty component.
Worn or defective mechanical components of drive system - Inspect drive system and replace faulty components.

Hydraulics Troubleshooting

Hydraulic system overheated
Incorrect hydraulic pressure setting - Correct setting is required.
Misadjusted or defective main relief valve - Adjust the valve or replace if necessary.
Hydraulic oil is contaminated - The oil must be changed.
Hydraulic oil level is low - Add oil to the hydraulic system.
Hydraulic pump is faulty - Repair or install new hydraulic pump.

Lift arm can't drop or lift
Damaged lift controls - Replace or repair.
Hydraulic pump malfunction - Change or repair hydraulic pump if required.
Hydraulic control valve is defective - Install a new valve or repair it.
Hydraulic cylinder is faulty - Repair or change hydraulic cylinder.
Hydraulic oil is insufficient - Check and refill the hydraulic oil.

Bucket does not tilt
Bucket controls failure - Change or repair.
Hydraulic pump failure - Install new pump or repair it.
Hydraulic control valve is defective - Repair or change hydraulic valve.
Bucket cylinder malfunction - Repair or change cylinder.
Hydraulic fluid level low - Add fluid as required.

Boom or bucket is working slowly
Worn hydraulic oil pump - Check pump flow and change pump if necessary.
Oil leaks from hydraulic cylinder - Install new cylinder seals.
Insufficient hydraulic fluid - Fill up the hydraulic fluid.
Worn or unadjusted hydraulic control valve - Repair or set correctly.
Low hydraulic pressure - Set pressure correctly.

Bucket or boom is working jerkily
Air trapped in hydraulic system - Bleed hydraulic system.
Plugged hydraulic oil filter - Clean or install new filter.
Contaminated hydraulic oil - Change hydraulic oil.
Cylinder tube or rod is scored - Replace failed component.

Hydraulic pump is noisy
Hydraulic leakage or low oil level - Repair hydraulic leaks or add oil as required.
Hydraulic filter is clogged - Service or replace hydraulic filter.
Plugged suction line - Clean suction line as required.
Pump sucks air - Bleed air.
Pump parts are faulty - Rebuild or install new pump.

Electrical Troubleshooting

Battery will not charge
Loose or corroded wire connections - Tighten or clean electrical wiring connections.
Battery terminal connectors are faulty - Change terminal connectors.
Bad cell in battery - Use a new battery.
Defective or loose belt - Adjust belt tension or replace belt.

Starter turns slow
Battery capacity is low - Low battery charging, charge as required.
Battery does not hold charge - Service battery or replace it.
Battery cables are disconnected or terminals are faulty - Check wiring and clean or replace terminals.

Starter motor is not working
Battery is drained or defective - Change or recharge battery.
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed.
Battery capacity is low - Recharge the battery.
Starter motor is faulty - Starter needs to be replaced.