247 and 257 Multi Terrain Loaders Machine Systems Caterpillar

Show/hide table

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.

Operate the machine in each direction. Note the noises that are not normal and find the sources of the noises.

Troubleshooting Problem List and Probable Causes

Problem 1

The piston pump ( hydrostatic) makes noise.

Probable Cause

1. The hydraulic oil level is low.

2. The hydraulic oil is aerated.

3. The viscosity of the hydraulic oil is incorrect.

4. The charge pressure is too low.

5. The brakes are not fully disengaging.

6. The hydraulic inlet strainer may be clogged.

7. The gear pump or the piston pump are worn.

8. The hydraulic oil filter may be clogged.

Problem 2

The drive torque is not at specifications.

Probable Cause

1. The crossover relief valve may be improperly set. Replace the crossover relief valve.

2. The crossover relief valve is stuck in the OPEN position. Replace the crossover relief valve.

3. The brakes are not fully disengaging.

4. The pilot pressure is too low.

5. The piston pump ( hydrostatic) may not be functioning correctly.

6. The piston motor may not be functioning correctly.

7. The pilot operated hydraulic control ( hydrostatic) may not be functioning properly.

Problem 3

The output of the piston pump is low.

Probable Cause

1. The hydraulic oil level is low.

2. The gear pump has excessive wear.

3. The pilot pressure is low.

4. The viscosity of the hydraulic oil is incorrect.

5. The speed sensing valve is out of adjustment.

6. The piston pumps have too much wear.

7. The crossover relief valves are not set to the correct specifications.

8. The pump may have an internal leak.

9. Both of the piston motors may have an internal leak.

10. The charge relief valve is out of adjustment.

Problem 4

There is no pressure from the piston pump.

Probable Cause

1. The hydraulic oil level in the hydraulic tank is low.

2. The pilot operated hydraulic control ( hydrostatic) is not functioning properly.

3. The charge relief valve is damaged.

4. The gear pump has failed.

5. The speed sensing valve may have failed.

6. The mechanical linkage between the piston pump and the engine has broken.

7. The piston pump has a severe internal leak.

Problem 5

The machine moves when the pilot operated hydraulic control ( hydrostatic) is in the NEUTRAL position.

Probable Cause

1. The pilot operated hydraulic control ( hydrostatic) is not functioning properly.

2. The neutral position of the piston pump is not set correctly.

3. The piston pump may be worn or damaged.

Problem 6

The machine will not start to move until the engine speed is very high.

Probable Cause

1. The speed sensing valve is not properly adjusted.

2. There may be a problem with the pilot operated hydraulic control ( hydrostatic).

3. The pilot pressure is too low.

4. The brakes may be engaged.

5. The charge pressure may be low.

Problem 7

The machine has low performance. The machine has weak force.

Probable Cause

1. HIGH IDLE is not set to the correct specifications.

2. Engine power is low.

3. The speed sensing valve is not properly adjusted.

4. A pilot operated hydraulic control ( hydrostatic) is not functioning correctly.

5. The viscosity of the hydraulic oil is incorrect.

6. The brakes are not fully disengaged.

7. The crossover relief valves are not set to the correct specifications.

8. The pilot pressure may be too low.

9. The orifices at the pilot operated hydraulic control ( hydrostatic) may be plugged.

10. The piston motors may be worn or the pumps may be worn.

11. The charge pressure is low.

Problem 8

The machine does not move correctly when the pilot operated hydraulic control ( hydrostatic) is actuated.

Probable Cause

1. The speed sensing valve may not be set correctly.

2. The charge pressure is too low.

3. The pilot operated hydraulic control ( hydrostatic) may not be functioning correctly.

4. The orifices at the pilot operated hydraulic control ( hydrostatic) may be plugged.

5. The piston motors may be worn or the pumps may be worn.

Problem 9

The charge pressure is low at LOW IDLE and HIGH IDLE.

Probable Cause

1. There is a leak in the system.

2. The charge relief valve is out of adjustment.

3. The gear pump is worn.

4. There is a restriction between the piston pump and the charge pump.

Problem 10

The brakes on the machine are dragging.

Probable Cause

1. The brake solenoid is sticking.

2. The brake solenoid is receiving poor voltage.

3. There is a bad internal seal on the piston motor.

4. The charge pressure is low.

5. The gear pump is worn.

6. There is a restriction between the charge pump and the piston pump.

Problem 11

The machine is not modulating correctly.

Probable Cause

1. The oil temperature is too low.

2. There is a restriction in one of the pilot lines.

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

4. The piston pump is worn or damaged.

5. The piston motors are worn or damaged.

Problem 12

The motor speed is low on both sides of the machine.

Probable Cause

1. The engine may have low power.

2. The machine may not have warmed up sufficiently.

3. The brakes may be partially engaged.

4. The speed sensing valve may be out of adjustment.

5. The pilot pressure may be incorrect.

6. The charge pressure may be low.

7. HIGH IDLE is not set to the correct specification.

8. The piston pump is worn or the piston motors are worn.

Problem 13

The machine does not track straight.

Probable Cause

1. The neutral null setting is incorrect.

2. The pilot operated hydraulic control ( hydrostatic) is not functioning correctly.

3. One section of the piston pump could be malfunctioning.

4. A piston motor may be malfunctioning.

5. The displacement stops on the piston pumps may need adjustment.

6. The orifices on the pilot operated hydraulic control ( hydrostatic) may be plugged.

Problem 14

The tracks keep coming off of the machine.

1. The track tension is too loose.

2. The machine is being operated on a transition or a slope.

3. There is debris in the undercarriage.

Problem 15

The track wears out too soon.

1. The track tension is too tight.

2. The machine is operated in rocky terrain, in concrete demolition, or in any application that requires a solid tire on the skid steer loader.

Problem 16

The hydrostatic system is noisy.

Probable Cause

1. The flushing valve in the piston motor is malfunctioning.

2. The piston pump is worn.

3. The charge pressure is low.

4. There is air in the hydraulic oil.