247 and 257 Multi Terrain Loaders Machine Systems Caterpillar

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

This section provides probable causes to known problems. Prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation". Perform a visual inspection of the machine. Refer to Testing and Adjusting, "Visual Inspection".

Troubleshooting Problem List and Probable Causes

Problem 1

The hydraulic oil temperature is too high.

Probable Cause

1. The hydraulic oil temperature sensor is malfunctioning.

2. The hydraulic oil is aerated.

3. A restriction of air flow through the oil cooler.

4. A restriction of oil flow through the oil cooler.

5. The ambient air temperature is too high.

6. Operating the machine with one or more relief valves open for an excessive period of time.

7. The oil cooler bypass valve is stuck in the OPEN position.

Problem 2

The hydraulic oil temperature is too low.

Probable Cause

1. There is excessive oil flow through the oil cooler.

2. The oil cooler, the oil tank and other components in the hydraulic system are not protected from cold air temperatures or winds.

3. The oil cooler bypass valve is stuck in the CLOSED position.

4. The ambient air temperature is too low.

Problem 3

There is a large amount of air in the oil.

Probable Cause

1. The hydraulic oil suction line between the tank and the pump may be leaking.

2. There is air in the hydraulic system after assembly, inspection, or testing.

3. Air is entering the hydraulic system during operation.

Problem 4

The fan speed is too low or too high.

Probable Cause

1. Check the relief valve for contamination.

2. If the fan speed is low at LOW IDLE, determine that the gear pump is functioning correctly by hooking up a flow meter. If the gear pump is functioning correctly, replace the fan motor.

3. If the fan speed is too low or too high at HIGH IDLE, adjust the relief valve. If the problem cannot be resolved by adjusting the relief valve, replace the relief valve.

Problem 5

There is no hydraulic oil flow out of the charge section of the gear pump.

Probable Cause

1. The linkage between the two sections of the gear pump has broken. Replace the gear pump.

2. There has been damage to the seals on the charge pump. Replace the gear pump.

Problem 6

Hydraulic oil flow out of the two sections of the gear pump is limited.

Probable Cause

1. Check the inlet line for a restriction.

2. The strainer for the inlet is clogged.

3. The oil level is too low.

4. The hydraulic oil temperature is too low.

5. The hydraulic oil is aerated.

6. The gear pump is worn.

7. There is a restriction or there is a leak in the hydraulic line from the hydraulic tank.

8. Check the mechanical linkage between the piston pump and the engine.

9. Check the mechanical linkage between the gear pump and the piston pump.

Problem 7

The hydraulic tank is pressurized.

Probable Cause

1. The breather for the hydraulic tank is clogged.

Problem 8

The fan motor is noisy.

Probable Cause

1. The makeup valve for the fan motor is stuck.

Problem 9

The lift circuit and the tilt circuit are not functioning properly.

Probable Cause

1. The main relief valve setting is too low.

2. The charge pressure is incorrect.

3. The pilot operated hydraulic control ( work tool) is not functioning properly.

4. The control valve ( work tool) is not functioning properly.

5. The orifices for the pilot operated hydraulic control ( work tool) are clogged.

6. The cylinder is not functioning properly.

7. The gear pump is not functioning properly.

8. One of the lines or one of the hoses is broken.

9. The diverter valve (if equipped) is not functioning properly.

10. The interlock system is not functioning properly.

11. The load is too heavy.

12. A line relief valve is set too low.

13. A load check valve on the control valve ( work tool) is stuck in the CLOSED position.

Problem 10

The auxiliary hydraulic system is not functioning.

1. The switch for the hydraulic shutoff valve is in the OFF position.

2. The auxiliary circuit switch is not functioning properly.

3. The fourth function control is not functioning properly.

4. The platform harness, the cab harness, or the harness for the pilot operated hydraulic control ( work tool) is not functioning properly.

5. The modulating valves are not functioning properly.

6. The orifices for the pilot operated hydraulic control ( work tool) are clogged.

7. The control valve ( work tool) is not functioning properly.

8. The work tool is not functioning properly.

9. The harness for the work tool is not functioning properly.

10. The ECM or the software is not functioning properly.

11. The line relief setting is too low.

12. The auxiliary circuit connections are not fully engaged.

Problem 11

All work tool functions and auxiliary functions are sluggish, erratic, or intermittent.

Probable Cause

1. The gear pump is not functioning properly.

2. The main relief setting is too low.

3. The pilot system pressure is incorrect.

4. The pilot operated hydraulic control ( work tool) is not functioning properly.

5. The hydraulic system is contaminated.

6. The control valve ( work tool) and the spools have an excessive amount of wear.

7. The charge pressure is too low.

8. The line relief valves are set too low or the line relief valves are damaged.

9. The orifices on the pilot operated hydraulic control ( work tool) are clogged.

10. The load check valve is partially closed.

11. The modulating valves are not getting an adequate amount of current or the modulating valves are sticking.

12. The seals on the lift spool are damaged or worn.

13. The cylinders may have leaks.

14. The diverter valve (if equipped) is not functioning properly.

15. The ball valve is not fully closed.

16. The power supply from the engine is low.

Problem 12

The gear pump makes noise and the cylinder rods move erratically.

Probable Cause

1. The hydraulic oil is aerated.

2. The viscosity of the oil is incorrect.

3. The setting of the main relief valve is too low.

4. There is a loose connection of the oil line on the inlet side of the pump.

5. The gear pump has too much wear.

6. The line relief valve is set too low.

Problem 13

The oil pressure in the hydraulic system is low.

Probable Cause

1. The setting of the main relief valve is too low.

2. The gear pump has too much wear.

3. The control valve ( work tool) and the valve spools have an excessive amount of wear.

4. The setting of the line relief valves is too low.

5. The pilot pressure is too low.

Problem 14

The work tool moves while the pilot operated hydraulic control ( work tool) is in the HOLD position.

Probable Cause

1. A spool in the pilot operated hydraulic control ( work tool) is sticking.

2. The control valve ( work tool) and the valve spools have an excessive amount of wear.

3. A piston seal in a cylinder has excessive wear.

4. There is an external leak between the control valve ( work tool) and the cylinder that is drifting.

5. The seals on the control valve ( work tool) could be worn.

6. The ball valve is not fully closed.

7. The load check valve could be stuck in the control valve ( work tool).

8. The line relief valve in the lift circuit is set too low or the relief valve is stuck in the OPEN position.

Problem 15

The work tool droops when the pilot operated hydraulic control ( work tool) is moved from the HOLD position to the RAISE position.

Probable Causes

1. The hydraulic oil is aerated.

2. The piston seals of the lift cylinder are worn.

3. The control valve ( work tool) and the valve spool have an excessive amount of wear.

4. The load check valve on the control valve ( work tool) may be open or leaking.

Problem 16

The work tool droops when the pilot operated hydraulic control ( work tool) is moved from the HOLD position to the TILT FORWARD position.

Probable Causes

1. The hydraulic oil is aerated.

2. The piston seals of the tilt cylinder are worn.

3. The control valve ( work tool) and the valve spool have an excessive amount of wear.

4. The line relief valves are damaged or worn.

Problem 17

The work tool will not lower to the ground when the engine is stopped.

Probable Cause

1. The accumulator is not properly charged.

2. The pilot pressure is low.

3. The seals on the control valve ( work tool) may be damaged or worn.

4. Charge pressure may be leaking past a solenoid in the interlock system.

5. The pilot operated hydraulic control ( work tool) is not functioning properly.

6. The interlock system is not functioning properly.

Problem 18

The machine has poor hydraulic performance when the engine is at HIGH IDLE.

Probable Cause

1. The setting for the corresponding line relief valve or for the main relief valve may be incorrect.

2. The gear pump may be worn.

3. The pilot pressure is low.

4. The cylinder may have internal leaks.

Problem 19

The line relief valves are noisy.

Probable Cause

1. The line relief valve is adjusted too low or the line relief valve is damaged.

2. The main relief valve is set too high.

Problem 20

There is instability in the hydraulic system.

Probable Cause

1. The diverter valve (if equipped) is damaged or worn.

2. The hydraulic oil is aerated.

3. The gear pump has excessive wear.

Problem 21

The diverter valve (if equipped) is not functioning properly.

Probable Cause

1. The electrical connection between the machine and the diverter valve has been broken.

2. The solenoid on the diverter valve is not functioning.

3. The spool in the diverter valve is stuck in the OPEN position.

4. The cylinder may have internal leaks.

Problem 22

The diverter valve (if equipped) is not making the bucket level with the ground.

Probable Cause

1. The diverter valve is out of adjustment.

2. The cylinder may have internal leaks.

3. The hydraulic lines for the lift circuit or the hydraulic lines for the tilt circuit may have leaks.