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Jlg 40f boom leaking down

Discussion in 'Other Construction/Demolition Equipment' started by ramnit, Jun 5, 2022.

  1. ramnit

    ramnit Member

    Joined:
    Oct 30, 2018
    Messages:
    7
    Location:
    sacto california
    So my 40f has been sitting for about 9 months ,outside covered, a friend was using it to replace siding on his house . Ran it off and on for a few days ,now the main boom is leaking down ,rather quickly you can see it drop in a matter of a minute or so.
    Not sure if it is the check valve on the main ram or the ram it's self. No visible leaks on either ram main or the little one on the back of the boom.
    Not sure what to do
     
  2. OFF

    OFF Senior Member

    Joined:
    Sep 30, 2009
    Messages:
    950
    Occupation:
    HD Mechanic
    Location:
    Alberta, Canada
    Normally on those it was the check valve that caused problems. Before you panic, check and make sure that all the manual decent valves are tightly closed.
     
  3. ramnit

    ramnit Member

    Joined:
    Oct 30, 2018
    Messages:
    7
    Location:
    sacto california
    Thanks for the response
    All valves are closed ,they have never been opened.
    I thought it might be the valve ,iam thinking of replacing or if not to difficult repair the valve, just never done it
    Thanks again
     
  4. OFF

    OFF Senior Member

    Joined:
    Sep 30, 2009
    Messages:
    950
    Occupation:
    HD Mechanic
    Location:
    Alberta, Canada
    I've learned to start with the simplest things first. Next step would be to obtain a lift cylinder holding valve. JLG #4640265 Counter Balance Valve.
    Should be available still
     
  5. ramnit

    ramnit Member

    Joined:
    Oct 30, 2018
    Messages:
    7
    Location:
    sacto california
    OFF
    Have any good ideas wheee to get a service or parts manual online
    Any ideas would be great
    Also any ideas on rebuilding the locking brakes and hub drives
    Thanks
     
  6. OFF

    OFF Senior Member

    Joined:
    Sep 30, 2009
    Messages:
    950
    Occupation:
    HD Mechanic
    Location:
    Alberta, Canada
    Yes, I have them. PM me with an email address and I will send them to you in PDF.

    The brakes were always a pain.......
     
    Gary Layton likes this.