BASE AS 5251496 - Caterpillar

Caterpillar recommends obtaining an oil sample and performing a SOS Oil Analysis at regular intervals to help prevent damage to components. Use the information in "Sampling Interval and Location of the Sampling Valve" in this OMM to find the proper sampling interval for your machine.
Open the compartment access doors for the hydraulic tank.
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Remove the filler cap breather (1) .
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Place a suitable container next to the machine. Place the drain hose (2) in the container. Remove the cap on the hose and drain the hydraulic system. Dispose of the oil in a proper manner.
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Remove the tank cover (3) and remove the return filter element (4) .
Inspect the inside of the tank for contamination. If contamination is found, remove the tank from the machine and clean the tank.
Clean the tank cover (3). Install a new gasket. Install the tank cover (3) .Note: See Operation and Maintenance Manual, "Hydraulic System Oil Filter - Change" for information on changing the filter element.
Replace the hydraulic system filter element (4) in the return line. Replace all other hydraulic system filter elements.
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There are two return filter elements (5) and (6). Place a suitable container under the filter elements in order to catch any spilled oil.
Remove the small filter (6). Discard the element in a proper manner. Remove the large canister (5). Remove the element from the canister. Discard the element in a proper manner.
Clean the filter base. All of the old seal must be removed.
Apply a thin coating of oil to the seal of the new filters.
Install the new filter by hand. When the gasket contacts the filter base, turn the filter by 270 degrees more. This will tighten the filter sufficiently.Note: Every new oil filter has rotation index marks that are spaced at 90 degree increments. Use the rotation index marks as a guide for tightening the oil filter.
Refill the hydraulic tank. See the Operation and Maintenance Manual, "Capacities (Refill) " for the correct amount of oil.
Discard the spilled oil in a proper manner. Discard the old elements in a proper manner.
Replace the filler cap breather.
Install the filler cap breather.
Start the engine. Run the engine for a few minutes. Check the hydraulic system for leaks.
Stop the engine.
Repair the leaks that were found.
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Maintain the oil in the middle of the sight gauge (7) .
Close the compartment access doors for the hydraulic tank.