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Bobcat 453 Troubleshooting

The Bobcat 453 skid steer loader is powered by 43.9 cubic inches (0.7L) Kubota D722-B vertical 3-cylinder indirect injection water-cooled diesel engine with a rated power of 18.8 hp (14 kW) at 3600 rpm. The Bobcat 453 is equipped with a radial-lift loader boom, 1-speed hydrostatic transmission, 60H drive chains, and 5.70x12 standard tires. The hydraulic system has a pump with fluid flow rate of 6.8 gpm (25.7 lpm). The hydraulic pressure is 1450 psi (100 bar). The skid steer loader has a rated operating capacity of 700 lbs (318 kg) and tipping load of 1430 lbs (650 kg). The lift height is 92.4 inches (2350 mm) to hinge pin, and dump height is 71.2 inches (1810 mm).

Engine Troubleshooting

Diesel hard to start or doesn't start
Air in the fuel pipes - Bleed the fuel pipes.
Fuel filter plugged - Replace the filter element.
Burnt or defective injection nozzle - Replace injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
The valve clearance is incorrect - Correct valve clearance.
Fuel injection pump is faulty - Replace or repair injection pump.

Engine starts and then shuts off
Dirty air cleaner - Clean or change.
Fuel filter element is dirty - Change or clean the filter element.
Problems with fuel injection pump tightness - Inspect fuel injection pump for leaks.
Clogged or defective injectors - Change or clean fuel injectors.
Fuel injection pump failure - Change pump or rebuild it.

Diesel shuts off while driving
Engine is cold - Warm up to required temperature.
Fuel filter is plugged - Clean the filter or install new filter element.
Air in the fuel pipes - Bleed the fuel pipes.
Faulty or dirty injection nozzles - Replace injection nozzles.
Improper fuel injection timing - Set the fuel pump timing correctly.

Engine stops when idling
Low idle speed set incorrectly - Correct low idle adjustment.
Fuel injection pump is not working correctly - Replace injection pump or repair it.
Fuel injector fault - Change or clean fuel injectors.
The valve clearance is not adjusted - Adjust valve clearance according to specifications.

Engine power loss
Air filter is clogged - Clean or change.
Faulty fuel injection nozzles - Clean or replace injection nozzles.
Improper fuel injection pressure - Check the fuel injection pressure and adjust if necessary.
The valve clearance is incorrect - Adjust valve clearance according to specifications.
Improperly adjusted low idle speed - Adjust as required.
Dirty fuel hoses or lines - Clean fuel system hoses and lines.
Defective cylinder head gasket - Replace the gasket as required.
Piston rings are worn or defective - Change piston rings.

Engine overheats
Lack of coolant in cooling system - Refill to the correct level and inspect system for leaks.
Engine oil level is low - Need to add engine oil.
Clogged radiator core or leaking radiator cap - Change cap or clean radiator.
Fan belt is broken or worn - Change the fan belt.
Engine is overloaded - Reduce engine load.

Insufficient oil pressure
Low crankcase oil level - Checking oil level and add if necessary.
Dirty oil filter element - Change or service engine oil filter.
Oil grade or viscosity is wrong - Use the specified type of engine oil.
Incorrect oil clearance in main bearing - Bearings need to be reinstalled.
Oil pump is worn or damaged - Repair or change.

Engine noise or knocking
Engine oil level low - Checking oil level and add if necessary.
Low coolant temperature - Warm up engine as required.
Wrong setting of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.
Wrong adjustment of low idle speed - Adjust low idle speed.
Defective fuel injectors - Inspect fuel injectors and change as required.
Connecting rod is defective or misaligned - Connecting rod needs to be replaced or aligned.
Pistons are worn or scored - Have pistons replaced.

Drive System Troubleshooting

Drive system doesn't work in either direction
Insufficient hydraulic fluid - Fill up the hydraulic fluid.
Faulty drive chain - Check drive chain and change defective components.
Stuck relief valve - Service or change relief valve.
Suction line or hydraulic filter is clogged - Replace hydraulic filter or clean suction line.
Worn or damaged foot or hand controls - Change or repair.
Drive motor or pump is worn - Replace or repair faulty component.

Loss of power
Hydraulic oil filter is clogged - Replace or service hydraulic filter.
Relief valve is damaged or open - Replace or close relief valve.
Transmission parts are defective or worn - Check and replace defective components.
Input drive shaft is defective - Replace drive shaft.
Air leaks in hydraulic system - Air bleeding is required.

Overheated drive system
Hydraulic fluid level low - Fill up the hydraulic fluid.
Hydraulic fluid filter is plugged - Change or service hydraulic filter.
Relief valve defective or worn - Change or repair defective relief valve.
Worn hydraulic motor or drive pump - Check and repair if required.
Oil cooler is clogged - Cooling fins should be cleaned.
Drive system overload - Reduce drive system load.

Drive system is excessively noisy
Oil viscosity is too heavy - Use correct oil viscosity.
Air trapped in hydraulic system - Bleed air from system.
Drive pump or hydraulic motor is damaged - Replace or repair faulty component.
Worn or damaged mechanical components of drive system - Check the components for worn or defect and replace if necessary.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is incorrect - Correct setting is required.
Main relief valve improper adjustment or failure - Set up or change the relief valve.
Contaminated hydraulic oil - Hydraulic oil change required.
Hydraulic oil level is insufficient - Check oil level and add hydraulic oil as required.
Hydraulic pump is worn - Repair or replace pump if necessary.

Lift arm fails to drop or lift
Lift controls are defective - Inspect and repair if necessary.
Damaged hydraulic oil pump - Replace or repair pump if necessary.
Faulty hydraulic control valve - Repair or change hydraulic valve.
Hydraulic cylinder malfunction - Replace or repair boom cylinder.
Low hydraulic oil level - Checking hydraulic oil level and add if necessary.

Bucket does not tilt
Damaged bucket controls - Change or repair.
Hydraulic pump failure - Change or repair hydraulic pump if required.
Hydraulic control valve is defective - Install a new hydraulic valve or repair it.
Defective bucket cylinder - Install a new cylinder or repair it.
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.

Boom or bucket functions slowly
Defective hydraulic pump - Test the pump performance and change pump if required.
Leaking hydraulic cylinder - Correct leakage by changing the seals.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.
Hydraulic control valve is unadjusted or worn - Repair or set properly.
Hydraulic pressure is low - Correct setting is required.

Jerky operation of the bucket or boom
Hydraulic system is leaking air - Need to bleed air.
Dirty hydraulic oil filter - Clean or install new filter.
Dirty hydraulic fluid - Fill up with fresh hydraulic fluid.
Scored cylinder tube or rod - Change damaged component.

Hydraulic pump is excessively noisy
Not enough oil or hydraulic system leaking - Remedy hydraulic leakage or refill oil as necessary.
Dirty hydraulic filter - Service or replace hydraulic filter.
Dirty suction line - Need to service the suction line.
Pump sucks air - Bleed air.
Damaged pump components - Replace or rebuild the pump.

Electrical Troubleshooting

Battery won’t charge
Loose or corroded cable connections - Tighten or clean connections.
Faulty battery terminal clamps - Terminal clamps need to be replaced.
Bad cell in battery - Replace the battery.
Loose or defective belt - Need to adjust belt tension or replace belt.

Starter turning slow
Battery power is low - Battery is drained, recharge it.
Battery is draining quickly - Service or change the battery.
Disconnected wiring or bad battery terminals - Connect wires correctly or change terminals.

Starter doesn't crank
Battery is drained or defective - Battery needs to be recharged or replaced.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Battery voltage is low - Battery is drained, recharge it.
Damaged starter motor - Starter needs to be replaced.