TUBE AS. 8V9431 - Caterpillar

Illustration 1. Typical stick valve group.Repair Procedure
Illustration 2. Location of valves in main control valve (viewed from front of machine). (1) Boom I. (2) Swing. (3) Stick I. (4) NFC Relief valve.1. Disconnect pilot line from upper end of each stem on hydraulic control valve group.2. Remove pilot housing from upper end of the respective stem being serviced.3. Remove stem assembly and install new valve group (spool kit) for the implement function being serviced.4. Install pilot housing and connect the pilot line.5. Change the NFC relief valves to new ones, if necessary.6. Set Engine Speed Dial to LOW IDLE position and start engine. Loosen fitting of pilot line at upper end of the boom (or stick) stem. Do not disconnect the fitting completely.7. Move the pilot control lever toward BOOM UP or STICK IN or SWING LEFT very slowly to bleed air from the loosened fitting.8. Tighten fitting.