416E, 420E and 430E Backhoe Loaders Hydraulic System Caterpillar

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

Problem List for the Hydraulic System

1. The temperature of the oil is too hot.

2. The pump makes unusual noise and the cylinder rods do not move smoothly.

3. A large amount of air is in the oil.

4. The pump standby pressure is too low.

5. The pump standby pressure is too high.

6. There is a pause before the pressure is reached in all circuits.

7. Any of the implements move, when the control lever is in the HOLD position.

8. The line relief valves are too noisy.

9. There is too much implement drift.

10. The implement droops, when the implement is moved from a partially raised position to a raised position.

11. All implement cycle times are too slow.

12. The cycle times for the backhoe boom, the cycle times for the bucket or the cycle times for the stick are too slow.

13. There is a long pause when the bucket enters the ground during the boom lower.

14. There is a long pause when the bucket enters the ground during the loader bucket lower.

15. The cycle times for the backhoe boom, the cycle times for the bucket or the cycle times for the stick are too fast.

16. The cycle times are too slow for the following: Loader Lift Cylinder, Tilt, Clam Bucket, Backhoe Extendable Stick, or Auxiliary Hydraulics

17. The swing cycle times are too slow.

18. The swing cycle times are too fast.

19. The cycle times for the stabilizer LOWER are too fast.

20. The cycle times for the stabilizer are too slow.

21. The stabilizers will not lower the machine.

22. The swing cylinders hit the swing stops hard.

23. The Auto Up mode for the stabilizers does not work.

Problem 1

The temperature of the oil is too hot.

Possible Causes

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

2. The viscosity of the oil is wrong or the wrong oil is used.

3. The pump is worn.

4. There is a restriction in flow due to a bent hose, a bent tube, or a restriction in an oil passage.

5. The load that is on the system is too high.

6. There is air in a hydraulic circuit.

7. There is a restriction to the flow of air through the oil cooler.

8. The outside air temperature is too hot.

9. The work tools are operated too long.

10. The piston seal on the pump is worn.

Problem 2

The pump makes unusual noise and the cylinder rods do not move smoothly.

Possible Causes

1. There is cavitation due to atmospheric low pressure.

2. The oil level in the hydraulic tank is too low.

3. The viscosity of the oil is wrong.

4. There is a loose connection on the inlet side of pump or the tube on the pump outlet is bent.

5. The pump rotating group is worn.

6. There is air in a hydraulic circuit.

Problem 3

A large amount of air is in the oil.

Possible Causes

1. There is a loose connection on the inlet side of pump.

2. The hydraulic system was not purged of air after assembly, inspection, or testing.

3. There is leakage in the cylinder seals and around the cylinder seals.

4. Check for loose fittings or cracked fittings.

5. The oil level is low.

6. There is aeration in the tank.

Problem 4

The pump standby pressure is too low.

Possible Causes

1. The pressure compensator is set too low.

2. The spring for the pressure compensator in the pump is broken.

3. The pump is not upstroking. The swashplate is blocked or the actuator spring is broken.

4. Because the setting for the torque limiter is wrong, the torque limiter opens and the torque limiter causes a leak in the signal network.

5. The signal network is blocked.

Problem 5

Pump standby pressure is too high.

Possible Causes

1. The flow compensator is set too high.

2. The flow compensator is not moving.

3. The pump is not destroking. The actuator piston is stuck or the swashplate is blocked.

Problem 6

There is a pause before the pressure is reached in all circuits.

Possible Causes

1. The margin pressure is low.

2. There is air in the signal network.

3. There is leakage in the signal network.

4. An orifice is slightly plugged in the signal network.

5. There is an incorrect orifice in the signal network.

Problem 7

Any of the implements move, when the control lever is in the HOLD position.

Possible Causes

1. The pilot control valve (if equipped) is stuck open.

2. The control valve spool or the bore for the valve spool may be worn excessively and may cause leaks.

3. There is leakage in the seals and around the seals of the piston in the cylinders that are affected.

4. There is a leak in the lines between the control valve and the cylinders.

5. The solenoid for the multipurpose bucket has current and the solenoid has contamination.

6. The makeup valves are open.

7. The swing check valves are open.

Problem 8

The line relief valves are too noisy.

Possible Causes

1. The line relief valves that are affected are set too low.

2. The springs in the line relief valves that are affected are broken or fatigued.

3. The pressure compensator valve is set too high.

Problem 9

There is too much implement drift.

Possible Causes

1. There is leakage in the seals and around the seals of the piston in the cylinder that are affected.

2. The line relief valve is set too low.

3. There is leakage past a line relief/makeup valve in the circuit that is affected.

4. The spool in the main control valve is not correctly centered. This problem can be caused by a broken spring, a sticky valve spool, or a control linkage that is not adjusted properly.

5. If the drift problem is in the stabilizer cylinders, the cause can be any of the possible causes. In addition, the lock valve in the stabilizer that is affected may not be seated properly. The problem can be from pilot pressure that is trapped.

6. The control valve spool or the bore for the valve spool may be worn excessively and may cause leaks. Refer to Systems Operation, "Control Valve (Lift) - If Equipped"

7. The lock check valves are open.

8. If significant drift is in the loader only, check for a failure in the dead engine lower valve (if equipped).

Problem 10

The implement droops, when the implement is moved from a partially raised position to a raised position.

Possible Causes

1. The signal passages in the main spool of the control valve that is affected is blocked. The signal passages may leak into the signal network.

2. The flow control spool is not operating properly.

3. The load check valve may be stuck in the boom circuit, the bucket circuit, or the stick circuit.

4. The margin pressure is set too low.

5. There is air in the signal network.

Problem 11

All implement cycle times are too slow.

Possible Causes

1. There is a blockage or a leakage in the signal network.

2. The standby pressure is set too low.

3. The pump does not upstroke fully. The actuator piston is stuck or the swashplate is blocked.

4. The pump is worn.

5. The pressure compensator valve is set too low.

6. The torque limiter is set too low.

7. The pilot pressure is low.

8. The orifices in the signal network are wrong.

9. The engine speed is too low.

Problem 12

The cycle times for the backhoe boom, the cycle times for the bucket or the cycle times for the stick are too slow.

Possible Causes

1. The control valve spool is not fully shifted for the circuit that is affected.

2. The load signal to the pump compensator valve is blocked or partially blocked or there is leakage in the signal network.

3. The line relief valve for the affected circuit is set too low.

4. The line relief valve or the makeup valve for the affected circuit is leaking.

5. The seals for the cylinders are leaking for the affected circuit.

6. The pilot valve pressure is low.

Problem 13

There is a long pause when the bucket enters the ground during the boom lower.

Possible Causes

1. The valve for back pressure that is located near the filter inlet for the backhoe stays open. The valve spring is broken or the valve is sticking.

2. The makeup valve does not open.

Problem 14

There is a long pause when the bucket enters the ground during the loader bucket lower.

Possible Causes

1. The valve for back pressure that is located near the filter inlet for the backhoe stays open. The valve spring is broken or the valve is sticking.

2. The makeup valve does not open.

Problem 15

The cycle times for the backhoe boom, the cycle times for the bucket or the cycle times for the stick are too fast.

Possible Causes

1. The standby pressure is set too high.

Problem 16

The cycle times are too slow for the following: Loader Lift Cylinder, Tilt, Clam Bucket, Backhoe Extendable Stick, or Auxiliary Hydraulics

Possible Causes

1. The control valve spool is not fully shifted for the affected circuits.

2. The load signal to the pump compensator valve is blocked or partially blocked or there is leakage in the signal network.

3. The line relief valve or the makeup valve for the affected circuits is set too low.

4. The line relief valve for the affected circuit is leaking.

5. The seals for the cylinders are leaking for the affected circuit.

6. There is a broken spring for the flow control spool.

7. The pilot pressure for pilot operated machines is too low.

Problem 17

The swing cycle times are too slow.

Possible Causes

1. The control valve spool is not fully shifted.

2. The load signal to the pump compensator valve is blocked or partially blocked or there is leakage in the signal network.

3. The line relief valve for the affected circuits is set too low.

4. The line relief valve for the affected circuit is leaking.

5. The seals for the cylinders are leaking for the affected circuit.

6. There is a broken spring for the flow compensator valve.

7. The crossover relief valves are set too low.

8. The swing cushion valve is not operating properly.

Problem 18

The swing cycle times are too fast.

Possible Causes

1. The orifices in the spool are not within the specification.

2. The standby pressure is set too high.

Problem 19

The cycle times for the stabilizer LOWER are too fast.

Possible Causes

1. The standby pressure is set too high.

Problem 20

The stabilizers will not lower the machine.

Possible Causes

1. There is a hydraulic lock, because the pilot signal passage to the lock valve is blocked.

2. The pilot pressure is too low.

3. There is contamination in the stabilizer control valve. Perform one of the following procedures.
   • Replace the stabilizer control valve.

   • Remove the stabilizer control valve. Disassemble the valve. Clean the valve. Replace any worn parts or damaged parts. Reassemble the valve.

Problem 21

The swing cylinders hit the swing stops hard.

Possible Causes

1. The head end snubber springs are broken on the affected cylinders.

2. The snubber is stuck on the affected cylinder rods.

3. The swing cushion valve is not operating properly.

Problem 22

The Auto Up mode for the stabilizers does not work.

Possible Causes

1. The timer for the Auto Up mode is not functioning properly.

2. The switches for the detent solenoid are not functioning properly.