259D Skid Steer Loaders Machine Systems – Hydraulic System Troubleshooting – Implement

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

• The hydraulic oil temperature sensor is malfunctioning.

• The demand fan is not operating properly.

• A restriction of air flow through the oil cooler.

• A restriction of oil flow through the oil cooler.

• The ambient air temperature is too high.

• Operating the machine with one or more relief valves open for an excessive time.

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

Problem 2

The hydraulic oil temperature is too low.

Probable Cause

• There is excessive oil flow through the oil cooler.

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

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

• The ambient air temperature is too low.

• The demand fan is not operating properly.

Problem 3

The fan speed is too low or too high.

Probable Cause

• The demand fan motor may be calibrated incorrectly.

• The solenoid on the fan motor is bad.

• The hydraulic temperature switch is bad.

• The coolant temperature switch is bad.

• Charge pump flow is low.

• Broken wire in the harness.

• Connector loose at solenoid.

Problem 4

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

Probable Cause

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

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

Problem 5

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

Probable Cause

• Check the inlet line for a restriction.

• The strainer for the inlet is clogged.

• The oil level is too low.

• The hydraulic oil temperature is too low.

• The gear pump is worn.

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

• If there is NO OIL FLOW, check the mechanical linkage between the hydrostatic piston pump and the engine.

• If there is NO OIL FLOW, check the mechanical linkage between the gear pump and the implement piston pump.

Problem 6

The hydraulic tank is pressurized.

Probable Cause

• The breather for the hydraulic tank is clogged.

Problem 7

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

Probable Cause

• The main relief valve setting is too low.

• The charge pressure is incorrect.

• The electrohydraulic control (work tool) is not functioning properly. Check the calibration of the joystick.

• The control valve (work tool) is not functioning properly. Check the calibration of the implement valve solenoids.

• The cylinder is not functioning properly.

• The work tool pump is not functioning properly.

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

• The interlock system is not functioning properly.

• The load is too heavy.

• A line relief valve is set too low.

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

Problem 8

The auxiliary hydraulic system is not functioning.

Probable Cause

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

• The auxiliary Quick disconnect block has an internal leak.

• The auxiliary controls on the joystick are not functioning properly.

• The platform harness, the cab harness, or the harness for the electrohydraulic control (work tool) is not functioning properly.

• The auxiliary solenoids are not functioning properly.

• The control valve (work tool) is not functioning properly. Check the calibration of the implement valve solenoids.

• The work tool is not functioning properly.

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

• The ECM or the software is not functioning properly.

• The line relief setting is too low.

• The auxiliary circuit connections are not fully engaged.

Problem 9

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

Probable Cause

• The work tool pump is not functioning properly.

• The main relief setting is too low.

• The hydraulic system is contaminated.

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

• The valve or joystick calibration is incorrect.

• The charge pressure is too low.

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

• The load check valve is partially closed.

• The auxiliary solenoid is not getting an adequate amount of current.

• The work tool cylinders or motor may have internal leaks.

• The power supply from the engine is low.

Problem 10

The work tool oil pressure in the hydraulic system is low.

Probable Cause

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

• The work tool pump has too much wear.

• The valve spool is not shifted fully due to improper valve calibration.

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

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

• The pilot pressure is too low.

Problem 12

The work tool moves while the electrohydraulic control (work tool) is in the HOLD position.

Probable Cause

• A piston seal in a cylinder is damaged.

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

• The dead engine lower valve is not fully closed.

• A load check valve could be stuck in the control valve (work tool).

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

Problem 13

The work tool drops when the electrohydraulic control (work tool) is moved from the HOLD position to the RAISE position.

Probable Causes

• The piston seals of the lift cylinder are damaged.

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

• The electrohydraulic operated control is not calibrated correctly.

Problem 14

The work tool drops when the electrohydraulic control (work tool) is moved from the HOLD position to the TILT FORWARD position.

Probable Causes

• The piston seals of the tilt cylinder are damaged.

• The line relief valves are damaged .

• The electrohydraulic operated control is not calibrated correctly.

Problem 15

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

Probable Cause

• The accumulator is not properly charged.

• The pilot pressure is low.

• The electrohydraulic control (work tool) is not functioning properly. Check the calibration of the joystick.

• The interlock system is not functioning properly.

• The dead engine lower valve may not be functioning properly or the ball valve is not fully actuated.

• The check valve in the pilot shut off valve manifold may be stuck open.

Problem 16

The machine has low hydraulic power or fails to meet implement cycle time specifications when the engine is in high idle.

Probable Cause

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

• The pilot pressure is low.

• The work tool pump may be worn.

• The cylinder may have internal leaks.

• The throttle pedal may not be calibrated correctly.

• The work tool control valve may not be calibrated correctly.

• The joystick control may not be calibrated correctly.