Home / Skid Steer Loaders / Bobcat Skid Steer Loaders / Bobcat S770

Bobcat S770 Troubleshooting

The Bobcat S770 skid steer loader driveline system components: a 230 cu.in (3.8L) Kubota V3800-DI-TE3 4-cylinder direct injection turbocharged diesel engine with a rated power of 88.1 hp (65.6 kW), and fully hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 23 gal/min (87.1 l/min). The system relief pressure is 3550 psi (245 bar). The Bobcat S770 is equipped with hydraulic wet disc brakes and 12x16.5-12 tires. The skid steer loader has a boom lifting force of 5490 lbs (2490 kg) and bucket breakout force of 5035 lbs (2285 kg). The rated operating capacity is 3350 lbs (1520 kg), and tipping load is 6700 lbs (3040 kg).

Engine Troubleshooting

Engine starts hard or doesn't start
Air in the fuel system - Air bleeding.
Dirty fuel filter - Change filter element.
Fuel injection nozzles are dirty or defective - Clean or replace injection nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Valve clearance is out of adjustment - Adjust valve clearance.
Fuel injection pump is damaged - Repair or replace injection pump.

Engine starts but immediately stalls
Air cleaner is clogged - Install new air cleaner element.
Fuel filter plugged - Service or replace the filter.
Fuel injection pump has loose connections - Tighten the connections.
Clogged or defective injectors - Change or clean fuel injectors.
Fuel injection pump malfunctioning - Rebuild or replace pump.

Engine stops unexpectedly during operation
Engine is not preheated - Warm up the engine.
Fuel filter is plugged - Change the filter element.
Air trapped in fuel system - Bleed air.
Fuel injection nozzles are damaged or dirty - Check and replace nozzles if required.
Fuel injection pump timing is not adjusted - Use the correct fuel injection pump timing adjustment.

Engine shuts off while idling
Low idle speed setting is not correct - Correct low idle adjustment.
Fuel injection pump damage - Install a new pump or rebuild.
Fuel injectors are dirty or defective - Clean or replace fuel injectors.
Valve out of adjustment - Correct valve clearance.

Engine power is insufficient
Plugged air cleaner - Clean or change.
Fuel injection nozzles fault - Check injection nozzles and replace if required.
Improper fuel injection pressure - Adjust pressure to proper level.
The valve clearance is not adjusted - Check and adjust.
Low idle speed setting is incorrect - Adjust the low idle speed.
Fuel lines or hoses are dirty - Clean fuel system lines and hoses.
Cylinder-head gasket is leaking - Install new cylinder head gasket.
Leaking or damaged piston rings - Piston rings replacement required.

Engine overheated
Coolant level is low - Refill to the correct level and inspect system for leaks.
Not enough engine oil - Checking oil level and add if necessary.
Faulty radiator cap or dirty radiator fins - Clean radiator or change cap.
Fan belt is broken or worn - Install new fan belt.
Engine is under excessive load - Reduce load on the engine.

Insufficient oil pressure
Not enough oil in the engine - Add oil to the engine crankcase.
Oil filter clogging - Replace or clean engine oil filter element.
Incorrect engine oil Use correct viscosity oil.
Crankshaft bearing oil clearance is excessive - Bearing needs to be changed.
Oil pump malfunction - Repair or replace.

Abnormal engine knocking or noise
Engine oil level low - Need to add engine oil.
Engine is not fully warmed up - Warm up to required temperature.
Improper fuel injection timing - Use the correct fuel injection pump timing adjustment.
Incorrect low idle speed adjustment - Adjust low idle speed.
Fuel injector fault - Replace or clean fuel injectors.
Connecting rod is worn or misaligned - Replace or align connecting rod.
Worn or broken pistons - Replace the pistons.

Drive System Troubleshooting

Machine will not move in either direction or one direction
Hydraulic fluid level low - Fill up the hydraulic fluid.
Drive chain is damaged - Check drive chain and change faulty parts.
Faulty input drive shaft - Replace or service the drive shaft.
Relief valve is damaged - Relief valve need to be replaced or repair.
Plugged suction line or hydraulic filter - Change hydraulic filter or service suction line.
Foot or hand controls are faulty - Repair or replace.
Worn drive motor or pump - Repair or replace faulty component.

Lack of power
Clogged hydraulic oil filter - Change or service hydraulic filter.
Damaged or opened relief valve - Change or close relief valve.
Faulty or damaged transmission components - Check and replace faulty components.
Worn input drive shaft - Service or change faulty drive shaft.
Air trapped in hydraulic system - Bleed hydraulic system.

Overheated drive system
Low hydraulic fluid level - Fill the system to proper hydraulic fluid level.
Clogged hydraulic fluid filter - Change hydraulic filter.
Stuck relief valve - Repair or change.
Worn hydraulic motor or drive pump - Check and repair if required.
Hydraulic oil cooler is dirty - Clean the cooling fins.
Overloaded drive system - Load needs to be reduced.

Excessive noise
Oil viscosity is incorrect - Use the specified type of oil.
Air leaks in hydraulic system - Bleed hydraulic system.
Drive pump or hydraulic motor is damaged - Inspect and change as required.
Worn or damaged mechanical components of drive system - Check drive system and change faulty parts.

Hydraulics Troubleshooting

Hydraulic system overheating
Hydraulic pressure is not correct - Adjust pressure as required.
Unadjusted or defective main relief valve - Set up or change the relief valve.
Dirty hydraulic oil - The oil must be changed.
Hydraulic fluid level is low - Fill the hydraulic system with oil.
Worn hydraulic oil pump - Repair or change pump if required.

Boom does not raise or lower
Damaged lift controls - Repair or change.
Hydraulic pump is broken - Repair or change pump if required.
Hydraulic control valve is faulty - Install a new valve or repair it.
Hydraulic cylinder not working - Install a new boom cylinder or repair it.
Hydraulic oil level low - Checking hydraulic oil level and add if necessary.

Bucket does not tilt
Bucket controls failure - Change or repair.
Hydraulic pump is broken - Repair or replace pump if necessary.
Hydraulic control valve is faulty - Install a new valve or repair it.
Defective bucket cylinder - Repair or replace cylinder.
Hydraulic fluid level low - Fill up the hydraulic fluid.

Bucket or lift arm is moving slowly
Worn hydraulic oil pump - Test pump flow rate and replace pump if required.
Leaking hydraulic cylinder - Cylinder seals need to be replaced.
Insufficient hydraulic oil - Check and refill the hydraulic oil.
Hydraulic control valve is not set properly or defective - Repair or set properly.
Hydraulic pressure loss - Adjust it correctly.

Jerky operation of the bucket or boom
Air trapped in hydraulic system - Air bleeding is required.
Hydraulic oil filter element clogging - Clean or replace the filter.
Dirty hydraulic fluid - Change hydraulic fluid.
Scratched cylinder rod or tube - Replace defective component.

Hydraulic pump makes excessive noise
Low oil level or hydraulic leaks - Refill hydraulic oil or repair leaks in system.
Hydraulic filter is clogged - Change or clean oil filter.
Suction line is clogged - Service the suction line.
Pump is sucking air - Bleed air from hydraulics.
Pump parts are worn out - Install new hydraulic pump or rebuild it.

Electrical Troubleshooting

Battery cannot be charged
Electrical cable connections are corroded or loose - Tighten or service connections.
Battery terminal clamps are defective - Terminal clamps should be changed.
Worn-out battery - Install a new battery.
Belt is loose or defective - Adjust belt tension or change the belt.

Starter motor turns slow
Low battery voltage - Recharge the battery.
Battery discharges quickly - Service charging system or install new battery.
Bad terminals or disconnected battery cables - Check wiring and clean or replace terminals.

Starter will not crank
Battery is low or faulty - Replace or charge as required.
Disconnected or improperly connected wiring harness - Inspect battery wiring harness and connect as required.
Battery voltage is low - Battery is drained, charge it.
Starter motor is faulty - Starter needs to be replaced.