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Bobcat 753 Troubleshooting

The Bobcat 753 skid steer loader driveline system components: a 134.1 cu.in (2.2L) Kubota V2203-EB vertical 4-cylinder water-cooled diesel engine with a rated power of 43 hp (31.8 kW), and single-speed hydro transmission. The hydraulic system has a pump with a rated capacity of 15.9 gal/min (60.1 l/min). The system relief pressure is 2750 psi (190 bar). The Bobcat 753 is equipped with a radial-lift loader boom, 80HS drive chains, and 10.00x16.5 standard tires. The skid steer loader has a max lift height of 109.1" (2770 mm) to hinge pin and dump height of 84.6" (2150 mm). The rated operating capacity is 1300 lbs (590 kg), and tipping load is 2600 lbs (1180 kg).

Engine Troubleshooting

Engine starts up hard or doesn't start
Air in the fuel lines - Bleed the fuel lines.
Fuel filter plugging - Clean the filter element.
Clogged or defective injection nozzles - Replace injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
The valve clearance is incorrect - Adjust valve clearance according to specifications.
Fuel injection pump malfunction - Replace injection pump or repair it.

Diesel starts but immediately stops
Plugged air filter - Install new air filter element.
Clogged fuel filter - Install new filter element.
Fuel injection pump leakage - Check the fuel injection pump for leaks and fix it.
Clogged or defective injectors - Inspect fuel injectors and change as required.
Faulty fuel injection pump - Repair or change injection pump.

Engine stops unexpectedly during operation
Engine is not fully warmed up - Warm up engine as required.
Fuel filter is plugged - Service or replace the filter.
Air in the fuel pipes - Bleed the fuel pipes.
Damaged or dirty injection nozzles - Test injection nozzles and change if necessary.
Wrong setting of fuel injection pump timing - Adjust fuel injection pump as required.

Engine stalls when idling
Incorrect low idle speed adjustment - Test and adjust.
Fuel injection pump malfunctioning - Rebuild or replace pump.
Defective fuel injectors - Replace or clean fuel injectors.
Valve clearance is out of adjustment - Have it adjusted.

Diesel engine is losing power
Air filter is plugged - Clean or change filter.
Faulty or dirty injection nozzles - Replace injection nozzles.
Fuel injection pressure is incorrect - Correct the pressure settings.
Valve out of adjustment - Adjust valve clearance according to specifications.
Low idle speed adjustment is incorrect - Correct low idle settings.
Dirt in the fuel hoses or lines - Clean fuel lines and hoses.
Cylinder head gasket is defective - Replace the gasket as required.
Leaking or defective piston rings - Install new piston rings.

Engine overheats
Lack of engine coolant - Top up coolant fluid and check system for leaks.
Engine oil level low - Fill up the oil to required level.
Faulty radiator cap or dirty radiator fins - Install new cap or clean radiator.
Damaged or worn fan belt - The fan belt needs to be replaced.
Engine overloaded - Load reducing required.

Oil pressure is insufficient
Oil level is insufficient - Add oil to the engine crankcase.
Oil filter clogged - Service or change engine oil filter element.
Oil grade or viscosity is incorrect - Fill up with the proper oil viscosity.
Crankshaft bearing has incorrect oil clearance - Bearings need to be reinstalled.
Oil pump is worn or damaged - Inspect and change as required.

Abnormal engine knocking or noise
Engine oil level low - Add oil to the engine crankcase.
Low coolant temperature - Warm up to required temperature.
Fuel injection pump timing is wrong - Set the fuel pump timing correctly.
Low idle speed adjustment is incorrect - Adjust the low idle speed.
Clogged or defective injectors - Inspect fuel injectors and change as required.
Misaligned or defective connecting rod - Connecting rod needs to be replaced or aligned.
Worn or scored pistons - Pistons need to be replaced.

Drive System Troubleshooting

Drive system will not operate in either direction
Insufficient hydraulic oil - Check and refill the hydraulic oil.
Faulty drive chain - Check drive chain and change defective components.
Faulty relief valve - Repair or replace.
Hydraulic filter or suction line is plugged - Clean suction line or replace hydraulic filter.
Defective hand or foot controls - Change or repair.
Drive motor or pump is worn - Repair or replace faulty component.

Low power
Dirty hydraulic oil filter - Change or service hydraulic filter.
Opened or defective relief valve - Close or change relief valve.
Transmission components are faulty or damaged - Check and change defective components.
Input drive shaft is defective - Change or repair faulty drive shaft.
Hydraulic system is leaking air - Bleed air from system.

Drive system is overheated
Insufficient hydraulic oil - Check and refill the hydraulic oil.
Plugged hydraulic fluid filter - Change or clean hydraulic filter.
Relief valver is broken - Change or repair defective relief valve.
Defective drive pump or hydraulic motor - Repair or change faulty component.
Hydraulic oil cooler is plugged - Clean the cooling fins.
Drive system is overloaded - Reduce drive system load.

Drive system is excessively noisy
Oil viscosity is wrong - Use oil of proper viscosity.
Air in the hydraulic system - Bleed air from hydraulic system.
Worn hydraulic motor or drive pump - Change or repair faulty component.
Mechanical components of drive system are defective or worn - Inspect the components for worn or defect and repair as required.

Hydraulics Troubleshooting

Hydraulic system is overheated
Hydraulic pressure is not adjusted correctly - Set pressure correctly.
Misadjusted or defective main relief valve - Adjust or replace the relief valve.
Hydraulic oil is contaminated - Change hydraulic oil.
Hydraulic oil level is low - Add oil to the hydraulic system.
Defective hydraulic pump - Install new pump or repair it.

Lift arm cannot be raised or lowered
Lift controls are faulty - Inspect and repair if necessary.
Hydraulic pump malfunction - Repair or replace pump if necessary.
Defective hydraulic control valve - Repair or replace hydraulic valve.
Hydraulic cylinder is defective - Repair or install a new lift cylinder.
Hydraulic fluid is insufficient - Add fluid as required.

Bucket can't tilt
Bucket controls failure - Replace or repair.
Defective hydraulic pump - Install new pump or repair it.
Hydraulic control valve malfunction - Repair or replace hydraulic valve.
Broken bucket cylinder - Repair or change cylinder.
Hydraulic oil level low - Need to add oil.

Boom or bucket runs slowly
Faulty hydraulic oil pump - Test the pump flow rate and change pump if required.
Leaking hydraulic cylinder - Replace cylinder piston seals.
Low hydraulic fluid level - Fill the system to proper hydraulic fluid level.
Hydraulic control valve is faulty or out of adjustment - Set correctly or repair.
Hydraulic pressure loss - Set pressure correctly.

Lift arm or bucket is jerky
Hydraulic system is leaking air - Bleed air from hydraulic system.
Hydraulic oil filter clogging - Replace or clean the filter.
Hydraulic fluid is dirty - The fluid must be changed.
Scratched cylinder rod or tube - Change failed component.

Excessive hydraulic pump noise
Insufficient oil level or leaking hydraulic system - Repair hydraulic leaks or add oil as required.
Clogged hydraulic filter - Replace or clean the filter.
Suction line is clogged - Clean suction line as required.
Pump sucks air - Bleed air from hydraulics.
Pump parts are worn out - Replace or rebuild the pump.

Electrical Troubleshooting

Battery does not charge
Loose or corroded cable connections - Clean or tighten connections.
Faulty electrical terminal connectors - Terminal connectors should be replaced.
Battery is defective - Battery change required.
Belt is worn or loose - Belt needs to be adjusted or replaced.

Starter turning slow
Battery power is low - Battery is drained, recharge it.
Battery is draining quickly - Service charging system or change battery.
Bad terminals or disconnected battery cables - Check wire connections and change or service terminals.

Starter is not cranking
Battery is drained or worn - Charge or replace the battery.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Low battery power - Low battery charging, charge as required.
Starter motor failure - Change or repair starter.