PIN 8I4313 - Caterpillar

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
The temperature of the oil is too hot.
The pump makes unusual noise and the cylinder rods do not move smoothly.
A large amount of air is in the oil.
The pump standby pressure is too low.
The pump standby pressure is too high.
There is a pause before the pressure is reached in all circuits.
Any of the implements move, when the control lever is in the HOLD position.
The line relief valves are too noisy.
The winch brake will not reapply.
The counterweight droops, when the counterweight is moved from a partially raised position to a raised position.
All implement cycle times are too slow. Problem 1The temperature of the oil is too hot.Possible Causes
The oil level in the hydraulic tank is too low.
The viscosity of the oil is wrong or the wrong oil is used.
The pump is worn.
There is a restriction in flow due to a bent hose, a bent tube or a restriction in an oil passage.
There is air in a hydraulic circuit.
There is a restriction to the flow of air through the oil cooler.
The outside air temperature is too hot.
The piston seal on the pump is worn.Problem 2The pump makes unusual noise and the cylinder rods do not move smoothly.Possible Causes
The oil level in the hydraulic tank is too low.
The viscosity of the oil is wrong.
There is a loose connection on the inlet side of pump or the tube on the pump outlet is bent.
The pump rotating group is worn.
There is air in a hydraulic circuit.Problem 3A large amount of air is in the oil.Possible Causes
There is a loose connection on the inlet side of the pump.
The hydraulic system was not purged of air after assembly, inspection or testing.
There is leakage in the cylinder seals or around the cylinder seals.
Check for loose fittings or cracked fittings.
The oil level in the hydraulic tank is too low.
There is aeration in the tank.Problem 4The pump standby pressure is too low.Possible Causes
The flow compensator is set too low.
The spring for the flow compensator in the pump is broken.
The pump is not upstroking. The swashplate is blocked or the actuator spring is broken.
The signal network is blocked.Problem 5Pump standby pressure is too high.Possible Causes
The flow compensator is set too high.
The flow compensator is not moving.
The load sensing relief valve is stuck or the load sensing valve is set too high.
The pump is not destroking. The actuator piston is stuck or the swashplate is blocked.Problem 6There is a pause before the pressure is reached in all circuits.Possible Causes
The margin pressure is low.
There is air in the signal network.
There is leakage in the signal network.
An orifice is slightly plugged in the signal network.Problem 7Any of the implements move, when the control lever is in the HOLD position. Possible Causes
The control valve spool or the bore for the valve spool