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help zx160lc when i boom down boom goes up

Discussion in 'Excavators' started by Btad, Apr 3, 2022.

  1. nowing75

    nowing75 Senior Member

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    i saw i guy use that as a testing method. Port fluid on the retract side and if the cylinder extends its bad seals.
     
  2. Btad

    Btad Well-Known Member

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    You are my hero
    The spool was stuck I had to put a pry bar in the top spring to get it out I did not have to pry hard but I could not pull it out by hand i could not see any problems with it put it back in and it moved good so put it back to gether and it works again the doom still bleeds off slow like a foot in 10 minutes
    But with all that said if it happens again I can fix it in about 30 minutes
    I am a a pretty good mechanic bit I never worked on hydraulic before now
    So thanks again
     
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  3. terex herder

    terex herder Senior Member

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    My guess is there was a piece of contamination that stuck the spool. Watch for signs of something in the hydraulic system coming apart. Hopefully the contamination was a piece of the bad piston seal that is allowing your boom to drift.
     
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  4. Btad

    Btad Well-Known Member

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    I will probably look at the boom cylinder
    One of these day soon when I get a chance
     
  5. Vetech63

    Vetech63 Senior Member

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    If you take care of it now it’s the difference between $300 and $3000. The machine has already given you a warning……proceed with caution.
     
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  6. aongheas.macask

    aongheas.macask Well-Known Member

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    where did you measure the foot,was it on the cylinder or at the bucket,all excavators will have a certain amount of drift
    On the cylinders unless you have load control / counterbalance valves fitted on the cylinder. Cat should be able to give you the allowable drift measurement
     
  7. aongheas.macask

    aongheas.macask Well-Known Member

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    Sorry, Hitachi should give you allowable drift measurement
     
  8. Vetech63

    Vetech63 Senior Member

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    1 foot in 10 minutes is way too much.
     
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  9. mg2361

    mg2361 Senior Member

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    They do. Bucket loaded and curled, arm all the way out. Maximum drift is 15mm in 5 minutes measured at the bucket to ground.
     
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  10. Btad

    Btad Well-Known Member

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    In your professional opinion
    Next step redo the boom cylinders
     
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  11. aongheas.macask

    aongheas.macask Well-Known Member

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    Seems strange to measure at the bucket,I would always measure at the hoist cylinder for an accurate reading if you suspect that is the one that is drifting, also if you suspect piston seals are bypassing them an easy test is to fully extend cylinder and hold against relief valve for a few minutes and if piston seals are bypassing the cylinder will beat up rapidly in the area where the piston sits.
     
  12. aongheas.macask

    aongheas.macask Well-Known Member

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    should read heat up not beat up
     
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  13. mg2361

    mg2361 Senior Member

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    I agree, that is just what the manual says. Later units have specs for rod travel so you are not subject to the influence of other cylinders leaking.
     
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  14. Vetech63

    Vetech63 Senior Member

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    Yeah ASAP! You could crater the cylinder and contaminate the entire hydraulic system. What you just dealt with is nothing compared to what that catastrophe while be.
     
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  15. Vetech63

    Vetech63 Senior Member

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    LOL.....thats like almost nothing! 12" in 10 minutes? It may be 5 feet in 10 minutes stretched out.:eek:
     
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  16. Btad

    Btad Well-Known Member

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    Will order parts Monday morning
    Any thing special that I should know when I put in new seal kits in
    Won't the filter catch ant of the seal do it won't contaminat the system?
    And again thank you do much
     
  17. Vetech63

    Vetech63 Senior Member

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    If you have trouble with the seal kit replacement just post pics. There are several different types of glands and I don’t know which you have.
    The system is filtered on the low/return side of the system. A failure in 1 circuit can contaminate the others through the common control valve. As you use the failing circuit, the return side feeds back into the main control valve which may make that return oil available for the following circuit if it is being used at the same time. A lot of this also depends on the type of control valve your machine is equipped with, whether it’s open/closed center and open/closed port.
     
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  18. Acoals

    Acoals Well-Known Member

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    As a general question, how much internal leak down is acceptable without running the risk of causing a major failure as you described? For reference my Cat 315's thumb will weep down, not 12" in ten minutes, but it will drop to the ground overnight from the folded position. I have a couple other functions on different machines that will weep down, or sag if they are holding a load.
    Also, what exactly do you mean by "cratering" the cylinder? What would happen internally that would cause this, and what exactly would be cratered, the cylinder walls?
     
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  19. Vetech63

    Vetech63 Senior Member

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    It’s not necessarily the leak down that bothers me in the op’s situation. It’s the fact that something in that boom circuit is coming apart (I assume it’s the cylinder packing) and a contaminant had already made it’s way to the main valve and hung it up. He only repaired a symptom and not what is causing it. If chunks, big enough to lock up the control spool, are coming off then odds are the metal of the piston can start dragging the sides of the barrel…..beginning a infusion of metal particles into the hydraulic system.
     
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  20. Acoals

    Acoals Well-Known Member

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    I see, thank you
     
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