SEAL 1438839 - Caterpillar

Install a 3B-7271 Pipe Nipple (5) with hose (6) into the hole on the bottom of the hydraulic tank.
Loosen drain plug (7) in order to drain the oil.
Drain the oil into a suitable container.
After the oil has been drained, tighten drain plug (7) to a torque of 110 15 N m (81 11 lb ft).
Remove Pipe Nipple (5) and hose (6).
Clean plug (4) and install the plug. Tighten the plug to a torque of 75 5 N m (55 4.8 lb ft).
Open the access door on the right side of the machine.
Clean the pump, the hydraulic lines, and the hydraulic tank.
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Remove the plug from the tube. Allow the oil to drain into a container.Note: Dispose of used filters and used fluids according to local regulations.
Inspect the O-ring. Replace the O-ring if wear or damage is evident.
Clean the plug. Install the plug and the O-ring into the drain port.
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(8) Bolts
(9) Washers
(10) Cover
(11) Spring
(12) Screen
Remove bolts (8), washers (9) and cover (10).Note: Dispose of used filters and used fluids according to local regulations.Note: Do not allow spring (11) to fall back into the tank.
Remove spring (11) and screen (12).Note: Refer to Operation and Maintenance, "General Hazard Information" for information on containing fluid spillage.
Wash the screen in a clean nonflammable solvent. Allow the screen to dry. Inspect the screen. Replace the screen, if the screen is damaged.
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(13) O-ring seal
Remove O-ring seal (13) from the screen.
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(14) O-ring seal
Inspect O-ring seals (13) and (14). Replace the O-ring seals if wear or damage is evident.
Install O-ring seal (13) on screen (12).
Install screen (12) and spring (11). Then install cover (10), washers (9), and bolts (8).Note: Make sure that the O-ring seals and the spring are properly positioned during installation.
Fill the hydraulic system oil tank. Refer to Operation and Maintenance Manual, "Capacities (Refill)".
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Inspect the O-ring seal on the filler plug for damage. Replace the O-ring, if necessary. Clean the filler plug. Install the filler plug.
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(15) Connector
(16) Seal
(17) Drain hose
When the main hydraulic pump has been serviced or the hydraulic oil has been replaced, the air in the hydraulic system must be purged. Do not start the engine until the main hydraulic pump has been filled with oil.Operating the hydraulic pump without proper lubrication will damage the pump and other hydraulic components.
When the hydraulic oil has been replaced, the air must be removed from the hydraulic oil system. To remove the air from the hydraulic oil system, follow Step 27.a through Step 27.g.Reference: Refer to Testing and Adjusting, "Main Hydraulic Pump Air Pressure - Purge" in the service manual.
While the engine is stopped, remove drain hose (17), connector (15) and seal (16) from the top of the pump. Add hydraulic oil through the opening.
Check the condition of seal (16). If the seal is damaged, replace the seal.
After the pump has been filled with oil, install drain hose (17), connector (15) and seal (16) to the original locations.
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(18) Negative flow control hose
(19) Vent plug
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