769D Off-Highway Truck and 771D Quarry Truck Caterpillar

Illustration 1	g00809883

The machine must be level. The parking brake must be engaged and the engine must be stopped.

1. Remove the filler cap in order to prevent a vacuum in the tank. Install the cap after the tank has been drained. This will prevent dirt from entering the system.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

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Illustration 2	g00524218

Note: Hand tighten the NPT pipe nipple. Do not use tools.

2. Remove the drain plug from the hoist and brake tank. Install a 88 mm (3.50 inch) long NPT pipe nipple in order to open the internal drain valve. The outer diameter of the NPT pipe nipple should be 25.4 mm (1 inch). Drain the oil into a suitable container.

3. Remove the pipe nipple. Clean the drain plug and install the drain plug.

4. Remove the tank filler cap.

5. Remove the retaining ring on the filler screen. Remove the screen.

6. Wash the cap and the filler screen in clean, nonflammable solvent. Allow the cap and the filler screen to dry.

7. Inspect the cap seal. Use a new seal if the used seal is damaged. Install the filler screen and the retaining ring.

8. Fill the hoist and brake tank. Refer to Operation and Maintenance Manual, "Lubricant Viscosities". Refer to Operation and Maintenance Manual, "Capacities (Refill)".

9. Add oil to the tank in order to raise the oil level to the safe starting range.

10. Start the engine and run the engine for approximately 15 seconds. The oil level will decrease as oil fills the system.

11. Stop the engine.

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Illustration 3	g00518506

12. Check the oil level in the tank. Fill the tank to the "FULL COLD" mark in the sight gauge.

13. Start the engine and operate the engine at low idle. Check the hydraulic system for leaks and make necessary repairs.

14. Once the oil is up to operating temperature, the oil must be maintained to the "FULL WARM" mark in the sight gauge.

15. Raise the dump body until the hoist cylinders are extended halfway. Lower the dump body and add oil, if necessary.

16. Raise the dump body until the hoist cylinders are fully extended. Lower the dump body and add oil, if necessary.

17. Repeat Step 15 and Step 16 until the oil level stabilizes at the "FULL WARM" mark in the sight gauge.

18. Install the filler cap.