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Bobcat 843 Troubleshooting

The Bobcat 843 skid steer loader driveline system components: Perkins 4.154 vertical 4-cylinder liquid-cooled diesel engine with a rated power of 54 hp (40.3 kW), and single-speed hydrostatic 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 843 is equipped with a radial-lift loader boom, 100H drive chains, and 8.25x15 standard tires. The skid steer loader has a maximum 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 hard to start or won't start
Air in fuel system - Bleed fuel system.
Fuel filter plugging - Change filter element.
Clogged or defective injection nozzles - Service or change injection nozzles.
Water in the fuel system - Change fuel and repair fuel system.
Valve clearance is out of adjustment - Correct valve clearance needs to be set.
Fuel injection pump is broken - Repair or install a new fuel pump.

Diesel starts but immediately stops
Air cleaner is dirty - Service or replace air cleaner.
Fuel filter plugged - Change filter element.
Fuel injection pump is leaking - Repair any leaks.
Dirty or defective injectors - Replace or clean fuel injectors.
Fuel injection pump is faulty - Repair or install new pump.

Engine stalls while running
Low coolant temperature - Warm up the engine.
Fuel filter element is dirty - Service or replace the filter.
Air in the fuel lines - Bleed the fuel lines.
Dirty or faulty injection nozzles - Inspect nozzles and replace if necessary.
Improper setting of fuel injection pump timing - Set up as recommended.

Engine stops at low idle speed
Improperly adjusted low idle speed - Adjustment required.
Faulty fuel injection pump - Change pump or rebuild it.
Dirty or defective injectors - Test and replace fuel injectors if necessary.
Improper valve clearance - Adjustment procedure required.

Lack of engine power
Dirty air filter - Install new air filter element.
Clogged or burnt injection nozzle - Check injection nozzles and replace if required.
Fuel injection pressure is incorrect - Adjust pressure to proper level.
Valve clearance is out of adjustment - Have it adjusted.
Too low idle RPM - Adjust low idle speed.
Restricted fuel hoses or lines - Service fuel hoses and lines.
Damaged cylinder-head gasket - Replace cylinder head gasket.
Leaking or defective piston rings - Change piston rings.

Engine overheating
Engine coolant is insufficient - Add coolant fluid and inspect the cooling system for leaks.
Not enough engine oil - Fill up the oil to required level.
Radiator core is dirty or radiator cap is damaged - Change cap or clean radiator.
Broken or loose fan belt - Change as required.
Engine overload - Load reducing required.

Oil pressure is low
Not enough oil in the engine - Fill up the engine oil.
Oil filter clogged - Clean or change engine oil filter.
Improper type of engine oil - Use oil of proper viscosity.
Incorrect crankshaft bearing oil clearance - Bearings need to be reinstalled.
Oil pump failure - Replace as required.

Engine knocking sound or abnormal noise
Engine oil level is insufficient - Check oil level and add oil as required.
Engine is cold - Warm up engine as required.
Fuel injection pump timing is wrong - Adjust according to specifications.
Low idle speed adjustment is incorrect - Normalize low idle speed.
Clogged or defective injectors - Clean fuel injectors or change it.
Connecting rod failure or misalignment - Align or replace connecting rod.
Pistons are worn or broken - Have pistons replaced.

Drive System Troubleshooting

Machine will not move in either direction or one direction
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.
Drive chain malfunction - Check drive chain and change faulty parts.
Relief valver is broken - Repair or install a new relief valve.
Dirty hydraulic filter or suction line - Service suction line or replace hydraulic filter.
Faulty foot or hand controls - Inspect and repair if necessary.
Defective drive pump or motor - Change or repair faulty component.

Loss of power
Clogged hydraulic oil filter - Check, clean, or change as necessary.
Open or damaged relief valve - Close or replace relief valve.
Transmission parts are faulty or damaged - Inspect and change faulty parts.
Input drive shaft malfunction - Repair or replace drive shaft.
Air leaks in hydraulic system - Bleed air from hydraulic system.

Drive system overheating
Hydraulic oil level is low - Fill the system to proper hydraulic oil level.
Hydraulic fluid filter is clogged - Check, clean, or change as necessary.
Defective relief valve - Repair or change.
Defective drive pump or hydraulic motor - Inspect and change as required.
Plugged hydraulic oil cooler - Clean cooling fins as required.
Transmission overloading - Load should be reduced.

Drive system is noisy
Incorrect oil viscosity - Use proper oil viscosity.
Air in hydraulic system - Air bleeding is required.
Damaged drive pump or hydraulic motor - Change or repair faulty component.
Worn or defective mechanical parts of drive system - Inspect the components for defect or damage and repair as needed.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure incorrectly adjusted - Set pressure correctly.
Faulty or improperly adjusted main relief valve - Replace or set up the relief valve.
Contaminated hydraulic fluid - The fluid must be changed.
Hydraulic fluid level is low - Add fluid to the hydraulic system.
Hydraulic pump is defective - Change or repair hydraulic pump if required.

Boom can't lift or drop
Lift controls failure - Change or repair.
Defective hydraulic pump - Repair or install new hydraulic pump.
Hydraulic control valve malfunction - Repair or change the valve.
Damaged hydraulic cylinder - Replace or repair boom cylinder.
Hydraulic fluid level low - Add fluid as required.

Bucket does not function
Bucket tilt controls are defective - Check and repair as required.
Defective hydraulic pump - Repair or install new hydraulic pump.
Hydraulic control valve malfunction - Repair or replace the valve.
Hydraulic bucket cylinder is defective - Replace or repair cylinder.
Low hydraulic fluid level - Checking hydraulic fluid level and add if necessary.

Bucket or lift arm runs slowly
Defective hydraulic pump - Flow-rate hydraulic pump and replace pump if necessary.
Hydraulic cylinder oil leakage - Repair leak by replacing the seals.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.
Hydraulic control valve is defective or set improper - Adjust properly or repair.
Hydraulic pressure has dropped - Correct adjustment is required.

Bucket or boom is jerky
There is air in the hydraulic system - Air bleeding is required.
Hydraulic oil filter clogging - Clean or replace the filter.
Hydraulic oil is contaminated - Fill up with fresh hydraulic oil.
Cylinder tube or rod scoring - Replace defective component.

Hydraulic pump makes excessive noise
Not enough oil or hydraulic system leaking - Correct hydraulic leaks or top up oil as needed.
Dirty hydraulic filter - Clean or change the filter.
Suction line clogging - Need to service the suction line.
Air trapped in hydraulic pump - Bleed air from hydraulics.
Worn pump components - Rebuild or replace hydraulic pump.

Electrical Troubleshooting

Battery won’t charge
Electrical cable connections are loose or corroded - Tighten or service connections.
Faulty battery terminal connectors - Replace terminal connectors.
Faulty cell in battery - Install a new battery.
Loose or defective belt - Belt needs to be adjusted or replaced.

Starter turns slowly
Low battery output - Battery is drained, charge it.
Battery won’t hold charge - Service charging system or install new battery.
Bad terminals or disconnected battery cables - Connect wiring correctly or install new terminals.

Starter is not cranking
Battery is drained or worn - Need to charge or replace the battery.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Battery power is low - Battery needs to be recharged.
Starter motor failure - Starter should be replaced.