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Bobcat 853 Troubleshooting

The Bobcat 853 skid steer loader is powered by 169 cu.in (2.8L) Isuzu 4JB1-PK03 vertical inline 4-cylinder liquid-cooled diesel engine with a rated power of 58 hp (43 kW) at 2600 rpm. The Bobcat 853 is equipped with a radial-lift loader boom, single-speed hydrostatic transmission, 100HS drive chains, and 12.00x16.5 standard tires. The hydraulic system has a pump with fluid flow rate of 18 gpm (68.1 lpm) or 24 gpm (90.8 lpm). The skid steer loader has a rated operating capacity of 1700 lbs (772 kg) and tipping load of 3420 lbs (1548 kg). The lift height is 119.6 inches (3035 mm) to hinge pin, and dump height is 93.1 inches (2365 mm).

Engine Troubleshooting

Engine starts hard or will not start
Air in the fuel pipes - Bleed the fuel pipes.
Fuel filter plugging - Change filter element.
Defective or clogged injection nozzle - Change fuel injection nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve clearance is wrong - Check and adjust as required.
Faulty fuel injection pump - Repair or install new pump.

Engine starts but stops suddenly
Air filter is clogged - Clean or change filter.
Fuel filter plugged - Clean or change the filter.
Problems with fuel injection pump tightness - Inspect fuel injection pump for leaks.
Defective or clogged fuel injectors - Replace fuel injectors.
Fuel injection pump failure - Change pump or rebuild it.

Engine stalls after running
Engine is not fully warmed up - Warm up the engine.
Dirty fuel filter - Change filter element.
There is air in the fuel system - Bleed the system.
Dirty or faulty injection nozzles - Service or change injection nozzles.
Timing of fuel injection pump is incorrect - Adjust according to specifications.

Engine stalls when idle
Incorrectly adjusted low idle speed - Correct low idle adjustment.
Fuel injection pump malfunction - Rebuild or replace pump.
Clogged or defective injectors - Clean fuel injectors or change it.
Valve out of adjustment - Need to adjust valve clearance.

Loss of engine power
Plugged air cleaner - Clean or replace element.
Defective or clogged injection nozzle - Clean or replace injection nozzles.
Insufficient fuel injection pressure - Adjust to correct pressure.
Incorrect valve clearance - Correct valve clearance needs to be set.
Low idle speed set incorrectly - Need to adjust idle speed.
Fuel hoses or lines clogging - Clean fuel system hoses and lines.
Cylinder head gasket is blown - Replace cylinder head gasket.
Leaking or damaged piston rings - Piston rings need to be replaced.

Engine is overheated
Lack of engine coolant - Add coolant and check the components of cooling system.
Insufficient engine oil - Checking oil level and add if necessary.
Dirty radiator core or defective radiator cap - Clean radiator or change cap.
Damaged or worn fan belt - Replace as required.
Engine is under excessive load - Reduce engine load.

Oil pressure is low
Low crankcase oil level - Fill the crankcase with oil.
Oil filter is dirty - Change or service engine oil filter.
Incorrect oil viscosity - Use proper viscosity oil.
Excessive crankshaft bearing oil clearance - Replace bearings.
Defective oil pump - Check and replace if necessary.

Abnormal engine knocking or noise
Engine oil level low - Fill the crankcase with engine oil.
Coolant temperature is low - Warm up the engine.
Improper setting of fuel injection pump timing - Check the fuel injection pump timing adjustment.
Incorrect low idle speed adjustment - Adjust as required.
Fuel injector fault - Clean fuel injectors or change it.
Connecting rod is worn or misaligned - Need to align or replace the connecting rod.
Pistons are worn or broken - Install new pistons.

Drive System Troubleshooting

Drive system won't operate in either direction
Insufficient hydraulic fluid - Add fluid as required.
Drive chain is worn - Check drive chain and change defective components.
Relief valve is stuck - Repair or change.
Suction line or hydraulic filter is clogged - Service suction line or replace hydraulic filter.
Defective foot or hand controls - Repair or change.
Drive motor or pump is worn - Repair or change faulty component.

Power is too low
Dirty hydraulic oil filter - Replace hydraulic filter.
Faulty or opened relief valve - Close or replace relief valve.
Faulty or damaged transmission components - Inspect and replace faulty parts.
Worn input drive shaft - Change or repair faulty drive shaft.
Hydraulic system is leaking air - Need to bleed air.

Drive system overheating
Hydraulic fluid is insufficient - Check and refill the hydraulic fluid.
Hydraulic fluid filter is dirty - Replace or clean hydraulic filter.
Worn or defective relief valve - Change or repair defective relief valve.
Hydraulic motor or drive pump is worn - Change or repair faulty component.
Hydraulic oil cooler is dirty - Cooling fins need to be cleaned.
Drive system overloaded continuously - Load needs to be reduced.

Excessive noise
Oil viscosity is too heavy - Use oil of proper viscosity.
Hydraulic system is leaking air - Bleed air from system.
Drive pump or hydraulic motor malfunction - Change or repair faulty component.
Worn or damaged mechanical components of drive system - Check the parts for worn or defect and replace if required.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure is not correct - Set pressure correctly.
Main relief valve is defective or unadjusted - Replace or set up the relief valve.
Hydraulic oil is contaminated - Change hydraulic oil.
Hydraulic oil level is low - Check oil level and add hydraulic oil as required.
Hydraulic pump is worn - Repair or install new hydraulic pump.

Lift arm won't raise or lower
Defective lift controls - Inspect and repair if necessary.
Hydraulic pump not working - Repair or install new hydraulic pump.
Hydraulic control valve is defective - Install a new valve or repair it.
Faulty hydraulic cylinder - Replace or repair boom cylinder.
Hydraulic oil is insufficient - Need to add oil.

Bucket tilt does not work
Faulty bucket tilt controls - Change or repair.
Hydraulic pump not working - Repair or replace pump if necessary.
Hydraulic control valve is faulty - Repair or change the valve.
Hydraulic bucket cylinder not working - Install a new cylinder or repair it.
Hydraulic fluid level low - Fill up the hydraulic fluid.

Slow bucket or lift arm action
Worn hydraulic oil pump - Test pump flow rate and replace pump if required.
Oil leaks from hydraulic cylinder - Cylinder seals need to be replaced.
Low hydraulic oil level - Check and refill the hydraulic oil.
Hydraulic control valve is faulty or out of adjustment - Repair or adjust correctly.
Hydraulic pressure has dropped - Correct adjustment is required.

Lift arm or bucket is jerky
Air leaks in hydraulic system - Bleed hydraulic system.
Plugged hydraulic oil filter - Replace or clean the filter.
Contaminated hydraulic oil - The oil must be changed.
Cylinder tube or rod scoring - Replace damaged component.

Hydraulic pump is excessively noisy
Hydraulic leakage or low oil level - Remedy hydraulic leakage or refill oil as necessary.
Clogged hydraulic filter - Replace or clean the filter.
Suction line is dirty - Need to service the suction line.
Pump is sucking air - Bleed air.
Faulty pump parts - Rebuild or install new pump.

Electrical Troubleshooting

Battery cannot be charged
Electrical cable connections are loose or corroded - Clean or tighten wiring connections.
Defective battery terminal clamps - Replace terminal clamps.
Battery is worn - Install a new battery.
Loose or worn belt - Need to adjust belt tension or replace belt.

Starter cranks slow
Battery voltage is low - Recharge the battery.
Battery won’t hold charge - Service charging system or replace battery.
Bad terminals or disconnected battery cables - Connect wiring correctly or install new terminals.

Starter does not work
Battery is low or faulty - Battery needs to be recharged or replaced.
Battery wires are disconnected or incorrectly connected - Check wires and connect correctly.
Low battery capacity - Charge the battery.
Starter motor is defective - Starter needs to be changed.