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Bobcat 853H Troubleshooting

The Bobcat 853H skid steer loader driveline system components: a 169 cu.in (2.77L) Isuzu 4JB1-PK03 4-cylinder naturally aspirated liquid-cooled diesel engine with a rated power of 58 hp (43 kW), and 1-speed hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 18 gal/min (68.1 l/min) or 24 gal/min (90.8 l/min). The Bobcat 853H is equipped with a radial-lift loader boom, 100HS drive chains, and 12.00x16.5 standard tires. The skid steer loader has a maximum lift height of 119.6" (3035 mm) to hinge pin and dump height of 93.1" (2365 mm). The rated operating capacity is 1700 lbs (772 kg), and tipping load is 3420 lbs (1548 kg).

Engine Troubleshooting

Diesel hard to start or doesn't start
Air trapped in fuel system - Bleed air.
Fuel filter plugging - Filter maintenance required.
Clogged or defective injection nozzles - Test injection nozzles and change if necessary.
Water or dirt in fuel system - Drain, flush, and service the system.
Improper valve clearance - Check and adjust as required.
Damaged fuel injection pump - Change or repair the pump.

Diesel starts but immediately shuts off
Plugged air cleaner - Service or replace air cleaner.
Fuel filter plugged - Clean or change the filter.
Fuel injection pump has loose connections - Tighten the connections.
Fuel injectors are dirty or defective - Replace fuel injectors.
Fuel injection pump is not working correctly - Install a new pump or rebuild.

Engine stops suddenly during operation
Low coolant temperature - Normalize the temperature by warming up the engine.
Fuel filter element is clogged - Replace the filter element.
Air in the fuel lines - Bleed the fuel lines.
Fuel injection nozzles are faulty or clogged - Service or change injection nozzles.
Incorrect adjustment of fuel injection pump timing - Set up as recommended.

Engine shuts off while idling
Improperly adjusted low idle speed - Correct low idle adjustment.
Fuel injection pump damage - Rebuild or change fuel pump.
Fuel injectors are faulty or clogged - Inspect fuel injectors and change as required.
Valve clearance is out of adjustment - Correct valve clearance needs to be set.

Loss of engine power
Dirty air cleaner - Clean or change.
Dirty or damaged injection nozzles - Replace injection nozzles.
Fuel injection pressure is wrong - Test fuel injection pressure and adjust it correctly.
The valve clearance is not adjusted - Correct valve clearance needs to be set.
Wrong adjustment of low idle speed - Test and adjust.
Clogged fuel lines or hoses - Clean fuel system hoses and lines.
Defective cylinder head gasket - Replace the gasket as required.
Leaking or defective piston rings - Piston rings replacement required.

Engine is overheated
Engine has a lack of coolant - Add coolant fluid and inspect the cooling system for leaks.
Low engine oil level - Fill the crankcase with engine oil.
Clogged radiator core or damaged radiator cap - Change cap or clean radiator.
Loose or defective fan belt - Replace the fan belt.
Engine overload - Load reducing is recommended.

Low oil pressure
Engine oil insufficient - Fill up the engine oil.
Oil filter element clogging - Service or replace engine oil filter.
Different type of engine oil - Drain crankcase and refill with correct oil.
Crankshaft bearing oil clearance is excessive - Change bearings.
Oil pump malfunction - Install a new pump.

Engine knocking or noise
Lack of engine oil - Fill up the oil to required level.
Engine is not warmed up to the required temperature - Warm up engine as required.
Improper setting of fuel injection pump timing - Set the fuel pump timing correctly.
Incorrect low idle setting - Need to adjust idle speed.
Defective fuel injectors - Replace fuel injectors.
Faulty or misaligned connecting rod - Need to replace or align the connecting rod.
Piston wear or scoring - Pistons need to be replaced.

Drive System Troubleshooting

Machine is not moving forward or backward
Hydraulic fluid is insufficient - Fill up the hydraulic fluid.
Faulty drive chain - Check drive chain and change faulty parts.
Relief valver is broken - Relief valve need to be replaced or repair.
Suction line or hydraulic filter is plugged - Clean suction line or change hydraulic filter.
Defective or worn foot or hand controls - Replace or repair.
Damaged drive pump or motor - Inspect and change as required.

Lack of power
Hydraulic oil filter is clogged - Replace or service hydraulic filter.
Worn or open relief valve - Close or replace relief valve.
Transmission components are worn or defective - Inspect and change faulty parts.
Input drive shaft failure - Replace drive shaft.
Air in the hydraulic system - Air bleeding is required.

Drive system overheating
Insufficient hydraulic fluid - Add fluid as required.
Dirty hydraulic fluid filter - Change hydraulic filter.
Relief valve is stuck - Repair or replace.
Hydraulic motor or drive pump is worn - Inspect and change as required.
Plugged hydraulic oil cooler - Cooling fins need to be cleaned.
Drive system overloaded continuously - Reduce drive system load.

Drive system makes excessive noise
Improper oil viscosity - Use oil of correct viscosity.
There is air in the hydraulic system - Need to bleed air.
Drive pump or hydraulic motor malfunction - Replace or repair faulty component.
Mechanical parts of drive system are damaged or worn - Inspect drive system and replace faulty parts.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure incorrectly adjusted - Adjust it correctly.
Unadjusted or defective main relief valve - Adjust the valve or replace if necessary.
Hydraulic oil contamination - Fill up with fresh hydraulic oil.
Lack of hydraulic oil - Fill the hydraulic system with oil.
Worn hydraulic oil pump - Repair or replace pump if necessary.

Boom cannot be lowered or raised
Lift controls are damaged - Change or repair.
Defective hydraulic pump - Replace or repair pump if necessary.
Faulty hydraulic control valve - Install a new hydraulic valve or repair it.
Defective hydraulic cylinder - Install a new boom cylinder or repair it.
Low hydraulic fluid level - Fill up the hydraulic fluid.

Bucket does not tilt
Damaged bucket controls - Replace or repair.
Hydraulic pump malfunction - Repair or change pump if required.
Hydraulic control valve failure - Repair or change the valve.
Broken bucket cylinder - Repair or replace cylinder.
Insufficient hydraulic oil - Need to add oil.

Boom or bucket moves slowly
Defective hydraulic pump - Test the pump flow rate and change pump if required.
Oil leaks from hydraulic cylinder - Install new cylinder seals.
Hydraulic fluid level low - Add fluid as required.
Worn or unadjusted hydraulic control valve - Repair or adjust properly.
Hydraulic system loosing pressure - Adjust pressure as required.

Lift arm or bucket movements are jerky
Hydraulic system is leaking air - Need to bleed air.
Hydraulic oil filter element clogging - Service or change the hydraulic filter.
Hydraulic oil is dirty - Hydraulic oil change required.
Cylinder tube or rod is scored - Change worn component.

Hydraulic pump is noisy
Leaking hydraulic system or insufficient oil level - Refill hydraulic oil or repair leaks in system.
Plugged hydraulic filter - Service or change hydraulic filter.
Suction line is clogged - Suction line must be serviced.
Air trapped in hydraulic pump - Air bleeding is required.
Worn pump parts - Rebuild or change hydraulic pump.

Electrical Troubleshooting

Battery won’t charge
Wiring connections are corroded or loose - Service or tighten connections.
Battery terminal clamps are defective - Terminal clamps should be changed.
Battery faulty cell - Use a new battery.
Belt is worn or loose - Adjust belt tension or change the belt.

Starter motor turns slow
Low battery capacity - Battery needs to be recharged.
Battery drains quickly - Service battery or change it.
Disconnected cables or faulty battery terminals - Check wire connections and change or service terminals.

Starter motor is not working
Battery is discharged or worn - Recharge or replace battery.
Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly.
Low battery capacity - Recharge the battery.
Starter motor failure - Replace or repair starter.