HOSE AS 3904975 - Caterpillar

Probable Causes
The oil level is low.
The pump is worn or damaged.
The implement solenoids are not calibrated.
The pilot pump controller relief valve is faulty.
The main control valve is contaminated or damaged
The pilot system pressure is low.
Implement pump margin is too lowRecommended Actions
Note: Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the machine. You must be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component that contains fluid. Dispose of all fluids according to local regulations.The Oil Level Is Low
Check the oil level. Add oil, if necessary. Refer to Operation and Maintenance Manual, SEBU8589, "Hydraulic System Oil Level - Check".The Pump Is Worn Or Damaged
Refer to Testing and Adjusting, "Operational Checks (Hydraulic System)" in this manual.Use the following procedure to determine the efficiency of the pump.
Remove the end of the implement pump case drain hose from the case drain manifold. Direct the end of the hose into a large bucket or a container suitable for holding hydraulic oil. Ensure that the case drain hose will stay in the bucket.
Start the engine and set the engine speed to HIGH IDLE.
Slowly RAISE the blade. As the blade begins to raise, redirect the oil flow from the case drain hose into a second, empty bucket. (The second bucket is needed to measure the volume of case drain oil accurately coming from the hose during the RAISE cycle.) At the same time the hose is directed into the second bucket, record the number of seconds that elapse while the blade is being raised. When the blade reaches the fully raised position, redirect the hose back into the first bucket, then shut off the engine.
Measure and record the volume of case drain oil in the second bucket. Also record the total amount of time that the case drain oil flow was directed into the second bucket.
Convert the two statistics from Step 4 into "Litres per Minute" or "Gallons per Minute". The volume of case drain oil in the bucket during the elapsed time is an indicator of the degree of inefficiency of the pump.
If the case drain volume is equal to or greater than 27 L/min (7.1 US gpm), then the pump is worn or damaged. Remove the pump and bench test the pump to confirm the test on the machine in Steps 1 through 5. If the bench test confirms the test on the machine, then repair or replace the pump. Retest the system. The Implement Solenoids Are Not Calibrated
Refer to Testing and Adjusting, "Calibration" in this manual.The Pilot Pump Controller Is Faulty
Refer to Testing and Adjusting, "Operational Checks (Hydraulic System)" in this manual.The Main Control Valve Is Contaminated Or Damaged
Refer to Testing and Adjusting, "Calibration" in this manual.The Pilot System Pressure Is Low
Refer to Testing and Adjusting, "Operational Checks (Hydraulic System)" in this manual.Implement Pump Margin Is Too Low
Refer to Testing and Adjusting, "Piston Pump (Implement) - Test and Adjust" in this manual.