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Thread: How to bleed air from hydraulics system.

  1. #1
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    How to bleed air from hydraulics system.

    Going on the theory that I might have some air trapped in the system, it is probably best to test that theory. We know that air is much lighter than oil so any air in a system would want to move towards the top. Almost seems there should be dedicated bleeders at the VERY top of the systems but that they are not. Bleeders towards the bottom of the boom, and on the pilot blocks on main valve block.


    Curious what procedure people use to work out air? I am also I guess trying to learn the exact symptoms of air in the system in the first place. I know the oil level in this machine is low and I sure hope it is not getting air from the tank. that would be BAD. I am a little reluctant to put more oil in until we drop it all and replace it. In short, that is oil down the drain.

  2. #2
    Senior Member Nige's Avatar
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    Those "bleeders" are actually "system pressure release valves" designed to be used for releasing pressure in the lines to a cylinder before disconnecting them so as to avoid getting sprayed with high pressure oil.

    Usually in the implement system the method of removing any trapped air would be to work the cylinder back and forth through its full stroke with the engine at low idle. That should get all the trapped air back to the tank and a simple top-up of oil completes the process.

    You can bleed the Implement Pilot system. Here is the procedure.

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    MAIN CONTROL VALVES
    Valves marked 1-7. Bleed valves for the release of air from the pilot system oil.

    1. Install the swing lock pin and lower the boom assembly to the ground.
    2. Turn the plunger on the track brake valve all the way in.
    3. Start the engine and set the governor control to high idle.
    4. Move the safety lever to the OPERATE position.
    5. Move the control lever for swing movement to the bumper spring for swing RIGHT position and hold it there.
    6. Open bleed valve (7) one-half turn and make adjustment as needed to remove air from the housing.
    7. Tighten bleed valve (7) when there is no more air in the oil flow from the bleed valve opening.
    8. Move the control lever to NEUTRAL.
    9. Do Steps 5, 6, 7 and 8 for swing LEFT using the bleed valve on the inboard end of the swing valve. [Opposite bleed valve (7)].
    10. Do steps 5, 6, 7 and 8 for bucket OPEN. Use the control lever for bucket movement and bleed valve (2).
    11. Do steps 5, 6, 7 and 8 for bucket CLOSED. Use the control lever for bucket movement and the bleed valve on the inboard end of the bucket valve. [Opposite bleed valve (2)].
    12. Do Steps 5, 6, 7 and 8 for boom LOWER. Use the control lever for boom movement and bleed valve (1).
    13. Do Steps 5, 6, 7 and 8 for stick OUT. Use the control lever for stick movement and bleed valves (4) and (5).
    14. Do Steps 5, 6, 7 and 8 for boom RAISE. Use the control lever for boom movement and the bleed valves on the inboard end of the boom valve and the boom crossover valve. [Opposite bleed valves (1) and (4)].
    15. Do Steps 5, 6, 7 and 8 for stick IN. Use the control lever for stick movement and the bleed valve on the inboard end of the stick valve. [Opposite bleed valve (5)].
    16. Push down on the right pedal and hold. Do Step 6 and 7. Use bleed valves (3) and (6).
    17. Push down on the left pedal and hold. Do Steps 6 and 7. Use bleed valves on the opposite end of the right and left track valves. [Opposite bleed valves (3) and (6)].
    18. Turn the plunger on the track brake valve all the way out.

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