- Hydraulic hoses and hydraulic lines
- Hydraulic oil level is low.
- The hydraulic oil contains a large amount of air.
Hydraulic Hoses and Hydraulic Lines
Kinks or restrictions in hydraulic lines or hoses may act like an orifice that creates excessive noise and heat as the high pressure oil is forced through a passage that is smaller than the original opening.
Be sure to check for these conditions on all hydraulic oil hoses, lines, tubes and fittings in the system or the circuit that are in question. Correct any problems that are found. Then retest the hydraulic system for any symptoms.
Check the oil level. Add oil, if necessary. Refer to Operation and Maintenance Manual, "Hydraulic System Oil Level - Check" for the 953D and 963D machines. Refer to Operation and Maintenance Manual, "Hydrostatic Transmission and Hydraulic System Oil Level - Check" for the 973D machines.
The Hydraulic Oil Contains A Large Amount Of Air
Check all of the fittings and connections for proper torque on the suction side of pumps or on negative pressure side of other motors and other components.
Check the fluid level sight gauge on the side of the hydraulic oil tank. If the hydraulic oil appears cloudy, check the inside of the hydraulic oil tank. Make sure that the suction tube and the return oil tube are in the proper position. Ensure that both tubes are submerged in the oil (return oil splashing or spraying back into the tank can aerate oil).
Examine implement cylinder rod seals for signs of oil leakage or seeping which may allow air to be drawn in when the rod end of the cylinder is below tank/ambient pressure (such as during bucket FLOAT).
Loosen oil line connections after each hydraulic component (pressure side) and examine the oil for aeration at each inspection point. If the oil appears aerated as the oil seeps out of the loosened connection then that component may be the source of the aeration. The aeration may also be occurring some place between that component and the prior component that showed no signs of aeration.
Examine the suction hoses, suction screens, and all suction lines, fittings, and connections from the suction manifold to the implement pumps, the fan pump, and the implement pump. Look for indications of oil leakage. If oil leaks from these lines or connections when the machine is shut down, the connections will also draw air into the hydraulic oil system during operation. This condition will cause the pumps to infuse the air and distribute it to the components in that system/circuit and then return the aerated oil back to the tank
Ensure that the procedure to purge the air from the hydraulic system was completed correctly.