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Bobcat 963 G-Series Problems

The Bobcat 963 G-Series skid steer loader is powered by Perkins 1004-40T 4-cylinder direct injection turbocharged diesel engine with a rated power of 105 hp (78 kW) at 2200 rpm. The Bobcat 963 is equipped with a radial-lift loader boom, single-speed or two-speed hydrostatic transmission, 100HS drive chains, and 14.00x17.5 standard tires. The hydraulic system has a pump with fluid flow rate of 26.2 gpm (99.2 lpm). The hydraulic pressure is 3000 psi (207 bar). The skid steer loader has a rated operating capacity of 3000 lbs (1360 kg) and tipping load of 6000 lbs (2722 kg). The lift height is 125" (3250 mm) to hinge pin, and dump height is 98.7" (2505 mm).

Engine Troubleshooting

Engine starts up hard or will not start
Air in the fuel system - Air bleeding.
Clogged fuel filter - Replace the filter element.
Dirty or damaged injection nozzles - If necessary, replace with a new nozzle.
Water in the fuel system - Change fuel and repair fuel system.
Improper valve clearance - Correct valve clearance needs to be set.
Fuel injection pump malfunctioning - Rebuild or replace pump.

Engine starts but then stalls
Air filter is clogged - Replace or clean air filter element.
Fuel filter plugging - Clean or change the filter.
Poor fuel injection pump tightness - Look for any leaks of fuel pump, tighten it fast.
Clogged or defective injectors - Replace fuel injectors.
Damaged fuel injection pump - Replace injection pump or repair it.

Diesel shuts off while driving
Engine is not preheated - Warm up to required temperature.
Fuel filter element clogging - Change the filter element.
Air in the fuel system - Air bleeding.
Faulty fuel injection nozzles - Install a new kit of correctly balanced nozzles.
Improper fuel injection timing - Use the correct fuel injection pump timing adjustment.

Engine stops at low idle speed
Low idle speed set incorrectly - Normalize low idle speed.
Defective fuel injection pump - Rebuild or replace pump.
Clogged or defective injectors - Test and replace fuel injectors if necessary.
Improper valve clearance - Have it adjusted.

Diesel engine loses power
Dirty air filter - Clean or replace element.
Faulty fuel injection nozzles - Replace injection nozzles.
Uneven fuel injection pressure - Test fuel injection pressure and adjust it correctly.
Valve clearance is wrong - Adjustment procedure required.
Too low idle RPM - Normalize low idle speed.
Fuel hoses or lines are clogged - Service fuel lines and hoses.
Worn cylinder head gasket - Cylinder-head gasket replacement required.
Defective or worn piston rings - Replace the piston rings as required.

Engine overheats
Coolant level is low - Fill radiator to proper level and check components for faults.
Engine oil level is insufficient - Need to add engine oil.
Dirty radiator core or faulty radiator cap - Install new cap or clean radiator.
Fan belt is loose or defective - Install new fan belt.
Engine overload - Load reducing required.

Insufficient oil pressure
Low oil level - Check oil level and add oil as required.
Clogged oil filter element - Service or replace engine oil filter.
Improper type of engine oil - Use proper viscosity oil.
Incorrect oil clearance in crankshaft bearing - Install new bearings.
Defective oil pump - Repair or replace.

Engine knocking or noise
Insufficient engine oil - Fill up the engine oil.
Low coolant temperature - Warm up the engine.
Wrong setting of fuel injection pump timing - Set it up as required.
Wrong adjustment of low idle speed - Adjust as required.
Damaged or clogged injectors - Inspect fuel injectors and change as required.
Connecting rod is defective or not aligned - Need to replace or align the connecting rod.
Scored or worn pistons - Pistons need to be replaced.

Drive System Troubleshooting

Drive system does not work in either direction
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.
Damaged drive chain - Check drive chain and change faulty components.
Faulty relief valve - Rebuild or install a new relief valve.
Plugged suction line or hydraulic filter - Check, clean, or change if necessary.
Foot or hand controls are damaged - Replace or repair.
Worn drive motor or pump - Inspect and change as required.

Reduced power
Dirty hydraulic oil filter - Change or clean hydraulic filter.
Open or damaged relief valve - Change or close relief valve.
Defective or worn transmission parts - Check and replace defective components.
Defective input drive shaft - Rebuild or change the shaft.
There is air in the hydraulic system - Need to bleed air.

Drive system overheats
Hydraulic oil is insufficient - Check and refill the hydraulic oil.
Hydraulic fluid filter is dirty - Replace hydraulic filter.
Relief valve defective or worn - Relief valve need to be replaced or repair.
Hydraulic motor or drive pump is worn - Inspect and change as required.
Clogged hydraulic oil cooler - Cooling fins should be cleaned.
Drive system is overloaded - Reduce the load.

Drive system makes excessive noise
Incorrect oil viscosity - Use oil of proper viscosity.
There is air in the hydraulic system - Bleed air from hydraulic system.
Drive pump or hydraulic motor malfunction - Inspect and change as required.
Mechanical components of drive system are defective or worn - Check drive system and change faulty parts.

Hydraulics Troubleshooting

Hydraulic system is overheated
Hydraulic pressure incorrectly adjusted - Hydraulic pressure must be set correctly.
Unadjusted or defective main relief valve - Adjust the valve or replace if necessary.
Contaminated hydraulic fluid - Fill up with fresh hydraulic fluid.
Lack of hydraulic fluid - Check and refill the hydraulic fluid.
Hydraulic pump is defective - Repair or change pump if required.

Lift arm does not lower or raise
Lift controls are faulty - Check and repair as required.
Damaged hydraulic oil pump - Repair or change pump if required.
Damaged hydraulic control valve - Replace or repair the valve.
Broken hydraulic cylinder - Change or repair lift cylinder.
Low hydraulic fluid level - Fill up the hydraulic fluid.

Bucket won't move
Damaged bucket controls - Repair or replace.
Hydraulic pump not working - Install new pump or repair it.
Damaged hydraulic control valve - Repair or change hydraulic valve.
Bucket cylinder failure - Install a new cylinder or repair it.
Hydraulic oil is insufficient - Need to add oil.

Bucket or lift arm moves slowly
Defective hydraulic pump - Test pump performance and replace pump if necessary.
Leaking hydraulic cylinder - Change cylinder piston seals.
Hydraulic fluid level low - Add fluid as required.
Hydraulic control valve is faulty or out of adjustment - Repair or adjust properly.
Hydraulic pressure loss - Adjust pressure correctly.

Bucket or boom movements are jerky
Air in the hydraulic system - Bleed hydraulic system.
Hydraulic oil filter is dirty - Clean or change the filter.
Hydraulic fluid is contaminated - Fill up with fresh hydraulic fluid.
Cylinder tube or rod scoring - Change damaged component.

Hydraulic pump is excessively noisy
Hydraulic leaks or lack of oil - Repair hydraulic leaks or add oil as required.
Plugged hydraulic filter - Service or replace hydraulic filter.
Suction line is dirty - Suction line must be serviced.
Air trapped in hydraulic pump - Need to bleed air.
Worn pump components - Rebuild or replace hydraulic pump.

Electrical Troubleshooting

Battery does not charge
Loose or corroded wire connections - Tighten or service connections.
Faulty battery terminal connectors - Terminal connectors should be replaced.
Battery faulty cell - Install a new battery.
Damaged or loose belt - Change belt or adjust belt tension.

Starter turns slow
Low battery power - Charge the battery.
Battery will not hold charge - Service or change the battery.
Faulty battery terminals or disconnected cables - Connect wires properly or change terminals.

Starter doesn't crank
Battery is low or faulty - Recharge or replace battery.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Battery voltage is low - Recharge the battery.
Defective starter motor - Starter should be changed.