Hydraulic Oil May Transfer To The Transmission Caterpillar

Problem:

The hydraulic oil transfers to the transmission. The only connections between the hydraulic system and the transmission are the shaft seals in the steering pump, the implement pump, and the 9T-1823 Valve Group (Diverter Valve). The diverter valve is the primary source of the oil transfer. The shaft seal on the implement pump being second, and the steering pump being the final source of oil transfer. However, before proceeding to the second and third sources, remove any debris that has built up at the hydraulic tank return line screen (located on the midbeam axle). Debris build-up at this screen can distort the implement pump shaft seal and cause oil transfer.

NOTE: The return line screen is usually replaced during the 1000 service hour oil change interval.

Solution:

If oil transfer is suspected, perform the following procedure in order to check for leakage. Begin with the 9T-1823 Valve Group.

Show/hide table

Hot oil and components can cause personal injury. Do not allow hot oil or components to contact skin.

Show/hide table

Personal injury or death can result without releasing all of the hydraulic pressure. Release all the pressure from the hydraulic system before any lines are disconnected.

Test Procedure

Illustration 1.

Steering Control Group. (Rear View) (1) Signal Line. (2) Valve Port.

1. Disconnect signal line (1) from the transmission. Check for leakage at diverter valve port (2) when the engine is running and the transmission is in NEUTRAL. Very little oil should be leaking at the ports. (Over 10 mL in 20 minutes is considered to be a problem.)

NOTE: Do not put the machine in gear with an uncapped transmission signal line.

Illustration 2.

Steering Control Group. (Right Side View) (3) Return Line Screen.

2. Check for debris build-up at return line screen (3).

3. If there is still hydraulic oil transfer, inspect both steering filter bases to make sure they are installed correctly. If the steering filter base orientation needs to be corrected, the steering filter elements must be changed.

If hydraulic oil transfer is still a problem after following the above procedure, remove the implement pump and install a new seal. If there is still oil transfer, replace the steering pump shaft seal.

Make sure to record the dimensions of the shaft and seal and other relevant information. Report the information to Caterpillar Agricultural Products Service Support at (815) 754-8426 or (815) 754-8332.

NOTE: Damaged seals or shafts would be variable items to have returned intact.

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