308C CR Excavator Hydraulic System – Relief Valve (Pilot) – Test and Adjust

  1. Place the machine on level ground.
  1. Stop the engine.
  1. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, “Hydraulic System Pressure – Release”.



    Illustration 1 g00858163

    Pilot oil manifold compartment

    (31) Pilot relief valve

    (32) Setscrew

    (33) Locknut

    (34) Pressure tap

  1. Connect a 6000 kPa (870 psi) pressure gauge to pressure tap (34) .
  1. Start the engine.
  1. Place the machine controls at the following settings: engine speed dial “10” and Low idle switch OFF. Refer to Testing and Adjusting, “Engine Performance – Test” for engine rpm settings.
  1. Place the hydraulic activation control lever in the UNLOCKED position.
  1. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
  1. Check the pilot relief valve setting at pressure tap (34) .
  1. The pilot relief valve setting should be 4100 to 4300 kPa (595 to 625 psi). If the pilot relief valve setting is not within the specification, adjust the pilot relief valve.
  1. In order to adjust the pilot relief valve, loosen locknut (33) .
  1. Turn setscrew (32) until the pressure gauge reading at pressure tap (34) is 4100 to 4300 kPa (595 to 625 psi).

    Note: Turning setscrew (32) clockwise increases the pressure. Turning setscrew (32) counterclockwise decreases the pressure.

    Note: Always make final pressure adjustments on pressure rise.

  1. Tighten locknut (33) to a torque of 49 ± 5 N·m (36 ± 4 lb ft).