Bobcat S740 Skid Steer Troubleshooting

The Bobcat S740 skid steer loader driveline system components: a 208.1 cu.in (3.4L) Bobcat Doosan D34 four-cylinder turbocharged diesel engine with a rated power of 74 hp (55 kW), and 1-speed or 2-speed hydro transmission. The hydraulic system has a pump with a rated capacity of 23 gal/min (87.1 l/min). The system relief pressure is 3500 psi (241 bar). The Bobcat S740 is equipped with a vertical-lift loader boom, 120 HSOC roller chains, and 12x16.5 tires. The skid steer loader has a maximum lift height of 132" (3355 mm) to hinge pin and dump height of 104.3" (2650 mm). The rated operating capacity is 3100 lbs (1405 kg), and tipping load is 6200 lbs (2810 kg).

Engine Troubleshooting

Engine difficult to start or doesn't start

Air in the fuel system - Air bleeding.
Fuel filter plugged - Change the filter element.
Fuel injection nozzles are damaged - Check and replace nozzles if required.
Water or dirt in fuel system - Drain, flush, and service the system.
The valve clearance is not adjusted - Have it adjusted.
Fuel injection pump is damaged - Replace or repair injection pump.

Diesel starts and stops

Air filter is clogged - Clean or replace element.
Fuel filter element is dirty - Change the filter element.
Fuel injection pump has loose connections - Tighten the connections.
Dirty or defective injectors - Replace or clean fuel injectors.
Faulty fuel injection pump - Replace or rebuild injection pump.

Engine stalls after running

Low coolant temperature - Warm up the engine.
Fuel filter element clogging - Replace filter element.
Air in fuel tank - Bleed fuel tank.
Faulty fuel injection nozzles - Replace injection nozzles.
Fuel injection pump timing is not adjusted - Adjust fuel injection pump as required.

Engine stalls when idle

Improperly adjusted low idle speed - Adjust low idling as recommended.
Fuel injection pump malfunctioning - Rebuild or replace pump.
Damaged or clogged injectors - Clean fuel injectors or change it.
Valve clearance is out of adjustment - Adjust valve clearance.

Diesel power loss

Air cleaner is clogged - Clean or replace air cleaner element.
Fuel injection nozzles are faulty or clogged - Check injection nozzles and replace if required.
Fuel injection pressure is wrong - Adjust to correct pressure.
Valve clearance is not correct - Adjust valve clearance.
Incorrectly adjusted low idle speed - Need to adjust idle speed.
Fuel hoses or lines are clogged - Clean fuel lines and hoses.
Cylinder head gasket defective - Change cylinder head gasket.
Piston rings are worn or defective - Piston rings need to be replaced.

Engine overheats

Engine coolant is insufficient - Add coolant and check the components of cooling system.
Low engine oil level - Check and refill engine oil.
Radiator fins are clogged or radiator cap is faulty - Clean radiator or install new cap.
Damaged or worn fan belt - If necessary, replace the belt.
Engine is overloaded - Load reducing required.

Oil pressure is low

Not enough oil in the engine - Fill the crankcase with oil.
Engine oil filter is plugged - Change or clean engine oil filter element.
Improper type of engine oil - Drain crankcase and refill with correct oil.
Incorrect crankshaft bearing oil clearance - Change bearings.
Oil pump is damaged - Repair or replace.

Engine noises or knocks

Engine oil level is low - Check and refill engine oil.
Coolant temperature is low - Warm up the engine.
Fuel injection pump timing is wrong - Adjust the pump as required.
Incorrect low idle setting - Adjust low idle speed.
Defective fuel injectors - Clean or replace fuel injectors.
Connecting rod misalignment or failure - Alignment procedure or replacement is required.
Scored or worn pistons - Install new pistons.

Drive System Troubleshooting

Drive system will not operate in either direction

Low hydraulic fluid level - Add fluid as required.
Faulty drive chain - Inspect drive chain and replace defective parts.
Input drive shaft failure - Replace or service the drive shaft.
Defective or worn relief valve - Change or repair defective relief valve.
Plugged hydraulic filter or suction line - Clean suction line or replace hydraulic filter.
Worn or damaged foot or hand controls - Repair or change.
Drive motor or pump is worn - Repair or change faulty component.

Power is too low

Hydraulic oil filter is plugged - Change hydraulic filter.
Relief valve is open or defective - Replace or close relief valve.
Defective or worn transmission parts - Check and change defective components.
Input drive shaft is damaged - Rebuild or change the shaft.
Air in the hydraulic system - Air bleeding is required.

Drive system overheating

Low hydraulic fluid level - Checking hydraulic fluid level and add if necessary.
Hydraulic fluid filter is plugged - Change hydraulic filter.
Relief valver is broken - Change or repair defective relief valve.
Worn hydraulic motor or drive pump - Replace or repair faulty component.
Hydraulic oil cooler is dirty - Clean cooling fins as required.
Transmission overloading - Reduce the load.

Drive system is noisy

Oil viscosity is incorrect - Use oil of correct viscosity.
Air in hydraulic system - Bleed air from hydraulic system.
Damaged drive pump or hydraulic motor - Repair or replace faulty component.
Mechanical components of drive system are damaged or worn - Inspect the components for defect or damage and repair as needed.

Hydraulics Troubleshooting

Hydraulic system overheated

Incorrect hydraulic pressure setting - Hydraulic pressure must be set correctly.
Unadjusted or defective main relief valve - Adjust or replace the relief valve.
Hydraulic oil is contaminated - Change hydraulic oil.
Lack of hydraulic oil - Fill up the hydraulic oil.
Hydraulic pump is defective - Install new pump or repair it.

Boom cannot be lowered or raised

Damaged lift controls - Repair or change.
Defective hydraulic pump - Replace or repair pump if necessary.
Hydraulic control valve malfunction - Change or repair hydraulic valve.
Hydraulic cylinder is broken - Repair or install a new lift cylinder.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.

Bucket fails to tilt

Defective bucket controls - Check and repair as required.
Hydraulic pump malfunction - Replace or repair pump if necessary.
Hydraulic control valve malfunction - Install a new hydraulic valve or repair it.
Bucket cylinder failure - Install a new cylinder or repair it.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.

Bucket or lift arm is moving slowly

Defective hydraulic pump - Check pump performance and change it if necessary.
Oil leaks from hydraulic cylinder - Repair leak by replacing the seals.
Hydraulic fluid level low - Checking hydraulic fluid level and add if necessary.
Hydraulic control valve is unadjusted or worn - Adjust properly or repair.
Hydraulic system loosing pressure - Hydraulic pressure must be set correctly.

Lift arm or bucket movements are jerky

Air trapped in hydraulic system - Bleed hydraulic system.
Plugged hydraulic oil filter - Clean or replace the filter.
Hydraulic oil is contaminated - Change hydraulic oil.
Cylinder rod or tube is scuffed - Replace defective component.

Excessive hydraulic pump noise

Hydraulic leakage or lack of oil - Remedy hydraulic leakage or refill oil as necessary.
Clogged hydraulic filter - Clean or change the filter.
Suction line is clogged - Suction line needs to be cleaned.
Air in hydraulic pump - Bleed air.
Faulty pump components - Install new hydraulic pump or rebuild it.

Electrical Troubleshooting

Battery will not charge

Corroded or loose electrical wire connections - Service or tighten connections.
Battery terminal clamps are defective - Terminal clamps should be changed.
Battery failing - Install a new battery.
Defective or loose belt - Belt needs to be adjusted or changed.

Starter turns slow

Low battery power - Battery is drained, charge it.
Battery discharges quickly - Service or replace the battery.
Terminals are faulty or battery cables are disconnected - Check wiring and clean or replace terminals.

Starter is not working

Battery is drained or defective - Need to charge or replace the battery.
Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly.
Battery voltage is low - Recharge the battery.
Faulty starter motor - Repair or replace starter.