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Thread: D4-7U hydraulics will not hold blade up slowly drops within a minute or two

  1. #11
    Join Date
    Nov 2017
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    446

    Default

    around here most machine shops will rubuild hydraulic cylinders. they will probably use oem parts if you order them and supply.
    D4 6U,1943 D4 2T,Laplant Choate C41 Carrimor Scraper

  2. #12
    Join Date
    Oct 2010
    Location
    Trinity, NC
    Posts
    53

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    my 7u dropped on right side. had cylinder rebuilt and it still dropped. I switched cylinders from another machine that did not drop and after installation it dropped. don't know what the cause is but it still drops. just learned to live with it. must be multiple causes for dropping.

  3. #13
    Join Date
    Jan 2017
    Posts
    394

    Default LEAKS - seeps

    Liquids are not compressible -

    It drops because of a leak - either in packing, hoses, pipes or valves.

    If you find no visible signs of oil leaking, that leaves the valves and packing glands. They all have seals.

    Leaving a load suspended on hydraulics or cable, etc. is a Taboo! Asking for trouble and injury at some point in time.

    cts

  4. #14
    Join Date
    Oct 2010
    Location
    Eastern iowa
    Posts
    36

    Default Blade drops

    Sounds like ram seal/packing,one way to know for sure.raise blade and hold up with forklift,unhook both hoses,plug lift hose and lower blade.if oil comes out up side hose,it is getting by ram piston.

  5. #15
    Join Date
    Jan 2007
    Location
    Moriches NY, Hancock Ma
    Posts
    2,374

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    along with this discussion, my D3B angle blade slowly turns to the right when pushing a load. I assume it is the piston seal on the right side leaking letting fluid go from the lower end to the top end and not the seal on the left side letting fluid from the top end to the lower end?? or both??
    Thanks--- Dan
    Cat 941B, Cat D2 4U, Cat D3B, Cat D4 7U, Cat D6 9U

  6. #16
    Join Date
    Nov 2007
    Location
    NW Ohio
    Posts
    3,366

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    Once in a while my D4 blade will drop quick, its the relief valve that will stick open in the front unit. After working it awhile it stops doing it.

  7. #17
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
    Posts
    14,746

    Default

    Again, need to know the cylinder #. Early and late are not the same piston seals or cushion (end of stroke) valves.

  8. #18
    Join Date
    Feb 2009
    Location
    Vining, Minnesota
    Posts
    486

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    Quote Originally Posted by dpendzic View Post
    along with this discussion, my D3B angle blade slowly turns to the right when pushing a load. I assume it is the piston seal on the right side leaking letting fluid go from the lower end to the top end and not the seal on the left side letting fluid from the top end to the lower end?? or both??
    Thanks--- Dan
    I have a swing arm haybine https://bigiron.blob.core.windows.ne...160mower-8.jpg that did as you describe. Had the cylinder rebuilt and problem solved.

    Rick

  9. #19
    Join Date
    Nov 2006
    Location
    Faunsdale, AL USA
    Posts
    4,048

    Sick

    Quote Originally Posted by dpendzic View Post
    along with this discussion, my D3B angle blade slowly turns to the right when pushing a load. I assume it is the piston seal on the right side leaking letting fluid go from the lower end to the top end and not the seal on the left side letting fluid from the top end to the lower end?? or both??
    Thanks--- Dan
    Sounds like one of those situations that could be caused by either one or both pistons' seals leaking.

    I usually find if one of a pair of cylinders is leaking, it's best to go ahead and rebuild both. The seals come to the end if their life at about the same time. Saves worrying about diagnosing which one is leaking and you deal with the mess once instead of twice.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

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