924G and 924GZ Wheel Loaders Steering System Caterpillar

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To help prevent possible injury before testing and adjusting any hydraulic system, perform the procedure that follows:

Read Testing and Adjusting, RENR3508, "Machine Preparation for Troubleshooting" and understand Testing and Adjusting, RENR3508, "Machine Preparation for Troubleshooting" before performing any procedures.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Performance tests for the steering system can be used for a diagnosis of poor performance and for finding the source of oil leaks inside the hydraulic system.

This section provides probable causes to a known problem. Since there may be several probable causes, specific inspections or specific instrument tests may be recommended. These inspections and tests will help to identify the cause that is most probable.

Note: To prevent environmental contamination, make sure that you clean up any spilled fluids properly.

Note: Make sure that you use hydraulic oil with the correct viscosity for the ambient temperature and for the operating conditions.

Reference: For more information on the correct oil viscosity for the 924G Wheel Loader, refer to Service Manual Module, SEBU7265, "Lubricant Viscosities and Refill Capacities". For more information on the correct oil viscosity for the 924Gz Wheel Loader, refer to Service Manual Module, SEBU7266, "Lubricant Viscosities and Refill Capacities".

Problem List

1. The steering metering pump makes noise and the steering cylinder rods do not move freely.

2. Too much force is needed to turn the steering wheel.

3. The machine does not turn when the steering wheel is turned.

4. The machine turns slowly in both directions.

5. The machine turns slowly in one direction.

6. The steering wheel does not return to the center position correctly.

7. The steering wheel turns without the operator's action.

8. The machine will not stay in a straight line.

9. Operation of the hand metering unit is erratic.

10. Operation of the hand metering unit is erratic.

11. The steering wheel has excessive free play.

12. The machine turns in the wrong direction when the operator turns the steering wheel.

Problem 1

The steering metering pump makes noise and the steering cylinder rods do not move freely.

Probable causes

1. There is a loose connection of the oil line on the inlet side of the pump. Refer to Service Manual Module, RENR3508, "Visual Inspection" in this module.

2. The oil level in the hydraulic oil tank is low. For the 924G, refer to Service Manual Module, SEBU7265, "Hydraulic System Oil Level - Check" for the proper procedure to check the oil level. For the 924Gz, refer to Service Manual Module, SEBU7266, "Hydraulic System Oil Level - Check" for the proper procedure to check the oil level.

3. The viscosity of the oil is incorrect. For the 924G, refer to Service Manual Module, SEBU7265, "Lubricant Viscosities and Refill Capacities" for the proper oil viscosity. For the 924Gz, refer to Service Manual Module, SEBU7266, "Lubricant Viscosities and Refill Capacities" for the proper oil viscosity.

4. The pressure and flow compensator valve is adjusted too low. Refer to Service Manual Module, RENR3511, "Piston Pump (Work Tool and Steering)" for the adjustment procedure for the pressure and flow compensator valve.

5. There is air in the steering hydraulic circuit. Refer to Problem 10.

6. The pump has too much wear. Refer to Problem 4.

7. The suction screen in the tank is blocked.

Problem 2

Too much force is needed to turn the steering wheel.

Probable causes

1. The oil level in the tank is low. For the 924G, refer to Service Manual Module, SEBU7265, "Hydraulic System Oil Level - Check" for the proper procedure to check the oil level. For the 924Gz, refer to Service Manual Module, SEBU7266, "Hydraulic System Oil Level - Check" for the proper procedure to check the oil level.

2. The oil is cold. For the 924G, refer to Service Manual Module, SEBU7265, "Engine Starting". For the 924Gz, refer to Service Manual Module, SEBU7266, "Engine Starting".

3. The steering cylinders have failed. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

4. The suction screen in the hydraulic oil tank is blocked. Refer to Service Manual Module, RENR3513, "Hydraulic Tank-Remove".

5. The margin pressure or the standby pressure is too low. Refer to Service Manual Module, RENR3508, "Steering Pump Margin Pressure Test" for the procedure to adjust the steering pump margin pressure. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby Test" for the procedure to adjust the standby pressure.

6. The pressure and flow compensator valve is adjusted too low. Refer to Service Manual Module, RENR3511, "Piston Pump (Work Tool and Steering)" for the adjustment procedure for the pressure and flow compensator valve.

7. Oil pressure from the steering metering pump is low. The pump is worn. Refer to Problem 4.

8. The steering metering pump is damaged. Refer to Problem 9.

9. The operation of the relief valves are not correct. Refer to Problem 9.

Problem 3

The machine does not turn when the steering wheel is turned.

Probable causes

1. The oil level in the tank is low. For the 924G, refer to Service Manual Module, SEBU7265, "Hydraulic System Oil Level-Check" for the proper procedure to check the oil level. For the 924Gz, refer to service Manual Module, SEBU7266, "Hydraulic System Oil Level-Check" for the proper procedure to check the oil level.

2. Dirt is in the hydraulic system. For the 924G, refer to Service Manual Module, SEBU7265, "Hydraulic System Oil Filter-Replace" for the proper procedure to replace the hydraulic oil filter. For the 924Gz, refer to Service Manual Module, SEBU7266, "Hydraulic SystemOil Filter-Replace" for the proper procedure to replace the hydraulic oil filter.

3. Leaks can occur at these locations: the seals in the steering cylinder pistons, the accessory valve between the cylinder lines and the ports. Refer to Service Manual Module, RENR3508, "Visual Inspection".

4. The operation of the steering metering valve is not correct. Refer to Service Manual Module, RENR3508, "Steering Time -Check".

5. The metering section of the hand metering unit has a lack of oil. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby-Test".

6. No oil flow is going to the hand metering unit. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby-Test".

7. Air is in the steering system. Refer to Problem 10.

8. The steering metering pump operation is not correct. Refer to Problem 9.

9. There is a restriction in the steering linkage. Refer to Problem 5.

10. The operation of the relief valves in the steering metering pump or the anticavitation valves in the steering metering pump is not correct. Refer to Problem 9.

11. The steering column upper shaft is loose or damaged.

12. The lower splines on the steering column may be disengaged or broken.

Problem 4

The machine turns slowly in both directions.

Probable cause

1. The steering axle is overloaded. For the 924G, refer to the Service Manual Module, SEBU7265, "Specifications and Model Views". For the 924Gz, refer to the Service Manual Module, SEBU7266, "Specifications and Model Views".

2. The operation of the steering metering pump is not correct. Refer to Service Manual Module, RENR3508, "Steering Time-Check".

3. The oil flow from the piston pump is low. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby-Test".

4. The margin pressure or the standby pressure is too low. Refer to Service Manual Module, RENR3508, "Steering Pump Margin Pressure Test" for the procedure to adjust the steering pump margin pressure. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby Test" for the procedure to adjust the standby pressure.

5. The seals in the steering cylinders leak. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

6. The operation of the relief valves in the steering metering pump are not correct. Refer to Problem 9.

Problem 5

The machine turns too slowly in one direction.

Probable causes

1. The steering linkage is worn or damaged. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

2. A seal in the steering cylinder leaks. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

3. There is a restriction in the steering metering valve. Refer to Problem 9.

4. The operation of the crossover relief valve is not correct. Refer to Problem 9.

Problem 6

The steering wheel does not return to the center position correctly.

Probable causes

1. The pressure in the tank line is high. Refer to Service Manual Module, RENR3508, "Metering Pump (Steering) - Test".

2. The valve spool in the steering metering valve has a restriction. Refer to Service Manual Module, RENR3513, "Metering Pump-Disassembly".

3. The centering springs in the steering metering pump are worn. Refer to Service Manual Module, RENR3513, "Metering Pump-Disassembly".

4. Contamination is in the steering metering pump. Refer to Problem 8.

5. The steering column is not in the correct alignment with the steering metering pump.

Problem 7

The temperature of the oil is too hot.

Probable causes

1. The viscosity of the oil is incorrect. For the 924G, refer to Service Manual Module, SEBU7265, "Lubricant Viscosities and Refill Capacities" for the proper oil viscosity. For the 924Gz, refer to Service Manual Module, SEBU7266, "Lubricant Viscosities and Refill Capacities" for the proper oil viscosity.

2. There is a restriction in the hydraulic lines. Refer to Service Manual Module, RENR3508, "Visual Inspection".

3. Air is mixed with the oil. Refer to Problem 10.

4. An auxiliary cooler may be required for rugged operations.

Problem 8

The steering wheel turns without the operator's action.

Probable causes

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Illustration 1	g00635329

1. The drive timing in the steering metering pump is not correct. The pin (1) must align with the valley of the internal gear (2) in the steering metering pump.

2. The centering spring in the steering metering pump is broken. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassembly".

3. Due to foreign material, the sleeve valves in the steering metering pump stick open. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassembly".

4. The steering column is not in the correct alignment with the steering control unit.

Problem 9

The machine will not stay in a straight line.

Probable causes

1. The cylinder rod is bent. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

2. The steering cylinder piston is loose. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

3. The cylinder relief valves or the anticavitation valves are leaking. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassemble".

4. The hand metering unit is worn. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassemble".

5. Air is in the hydraulic system. Refer to Problem 10.

Problem 10

Operation of the hand metering unit is erratic.

Probable causes

1. Air is in the hydraulic system. Refer to Service Manual Module, RENR3508, "Visual Inspection". For the 924G, refer to Service Manual Module, SEBU7265, "Hydraulic System Oil Level-Check". For the 924Gz, refer to Service Manual Module, SEBU7266, "Hydraulic System Oil Level-Check".

2. A steering cylinder piston is loose. Refer to Service Manual Module, RENR3513, "Steering Cylinder-Remove".

3. The flow control spool is sticking. Refer to Service Manual Module, RENR3513, "Steering Pump-Disassemble".

Problem 11

The steering wheel has excessive free play.

Probable causes

1. The steering wheel nut is loose. Refer to Service Manual Module, RENR3513, "Steering Wheel-Remove".

Problem 12

The hand metering unit locks up.

Probable causes

1. Insufficient hydraulic power is being received from the steering piston pump. Refer to Service Manual Module, RENR3508, "Steering Pump Low Pressure Standby-Test".

2. Large dirt particles are in the metering section of the hand metering unit. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassembly".

3. The pin between the spool and the sleeve is severely worn or broken. Refer to Service Manual Module, RENR3513, "Metering Pump (Steering)-Disassembly".

Problem 13

The machine turns in the wrong direction when the operator turns the steering wheel.

1. The hydraulic lines to the steering cylinders are connected to the wrong ports on the hand metering unit. Refer to Service Manual Module, RENR3508, "Metering Pump (Steering)" in this module.