MAINTENANCE PROCEDURE MAINTENANCE Hydraulic System - Bleed Air 0. NOTICE If the pump is operated without filling the pump case with hydraulic oil, there is danger that the pump may be prematurely damaged. Be sure to bleed the air completely. 1. Bleeding air from piston pump 1) Remove the oil filler cap from the hydraulic oil tank. 2) Open cover (1) at left side of machine. 3) Loosen air bleeder (2) and confirm that oil oozes through it (the all air has been bled.) 4) After bleeding air, tighten the air bleeder. Tightening torque: 8.83 ± 0.98 N·m (0.9 ± 0.1 kgf·m, 6.5 ± 0.7 lbft) 5) Tighten the oil filler cap of the hydraulic oil tank. NOTICE Be sure to pressurize the hydraulic tank.
If it is not pres- surized, the pump will suck in air, and this will adversely affect the equipment. 6) Extend the boom, arm, and bucket cylinder fully as shown in the diagram on the right. Remove the oil filler cap, then install the cap and pressurize the inside of the tank. 7) After bleeding air from the hydraulic tank, check the oil level. Refer to section "Hydraulic Oil Level - Check/Add ( 3-36 )" in this manual. NOTICE If the engine is run immediately at high speed or the cylinder is operated to the end of its stroke, the air inside the cylinder may cause damage to the piston packing. 2. Start the engine. For details, see "STARTING ENGINE ( 3-43 )".
Run the engine at low idling for 10 minutes, then do as follows. 3. Bleeding air from cylinders 1) Run the engine at low idling, and extend and retract each cylinder 4 to 5 times. Do not operate the cylinder to the end of its stroke. (Stop at a point approx. 100 mm (4 in) before the end of the stroke.) 2) Next, operate each cylinder 3 to 4 times to the end of its stroke. 3) Finally, operate each cylinder 4 to 5 times to the end of its stroke to completely remove the air. 4-40