D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Hydraulic System Oil Level Is Low Caterpillar


Hydraulic System Oil Level Is Low
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1.1. Probable Causes
2.1. Recommended Actions
3.2. Hydraulic Oil Level In The Tank Is Decreasing
4.2. Leaks At Fittings And Other Types Of Hydraulic Line Connections
5.2. Oil Leaking Or Seeping At Tube Connections, Hose Connections, And At The Bypass Valve

------ WARNING! ------

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.


Probable Causes

  • Hydraulic oil level in the tank is decreasing.

  • Leaks at fittings and other types of hydraulic line connections

  • Hydraulic oil is leaking or seeping at a tube connection, a hose connection, or at the bypass valve

Recommended Actions

Note: Care must be taken in order 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.

Hydraulic Oil Level In The Tank Is Decreasing

Inspect the following items of the hydraulic tank for oil leakage:

  • All of the weld joints

  • All of the bolted covers and components

  • All fittings

  • All hose flange connections

Oil may leak out of the system if the welds are damaged, if covers and components have the seals or gaskets gaskets installed improperly, or if the bolts and fittings are improperly torqued. Correct any of the problems that are found. Fill the hydraulic tank with the correct oil. Monitor the tank in order to ensure that the leaks have been stopped.

Leaks At Fittings And Other Types Of Hydraulic Line Connections

Check for leaks at all fittings and connections of hydraulic oil hoses/lines/tubes in the system in question. Correct any problems that are found then retest for the symptom(s).

Leaks at fittings and other types of hydraulic line connections can cause loss of oil flow and prevent components from attaining pressures necessary to perform work. Pressure losses generate complaints of weak force such as the blade tilt or the lift force and implements drifting while in the HOLD condition. Flow losses generate complaints of component speed such as the fan speed or the cylinder speed.

Leaks at fittings and connections on the pressure side of pumps are a direct source of oil loss in the system, which can lead to component failure if the low oil levels are not monitored and pumps and motors are starved of oil.

Leaks at fittings and connections on the suction side of pumps are a direct source of oil aeration, which can also cause cavitation damage to components and create excess or unusual noise as well.

Oil Leaking Or Seeping At Tube Connections, Hose Connections, And At The Bypass Valve

Perform this inspection before cleaning the core.

Inspect the hydraulic oil cooler for leaks. Thoroughly examine all surfaces, tubes, and connections on the hydraulic oil cooler for signs of leaks. If oil is leaking, dirt and dust will adhere to the oily surfaces more than dry surfaces. Tighten any loose connections or fittings that might be leaking and recheck for leaks.

Thoroughly clean the cooler. Examine any suspected areas found during initial the inspection while the machine is running and the oil has been warmed to operating temperature in order to allow the bypass valve to close. Look for oil leaking or seeping at tube connections, hose connections, and at the bypass valve. Tighten any loose connections or fittings that might be leaking and recheck for leaks. The hydraulic oil cooler should be replaced if there are leaks on surfaces in addition to the fittings.

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