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unimount lift-cylinder stuck

Discussion in 'Western Plows Discussion' started by grizbait, Oct 5, 2008.

  1. grizbait

    grizbait Junior Member
    Messages: 18

    Broke out the plow to get ready for the season, and I'm having issues with the lift cylinder / rod not lifting more than 4-6 inches. It turns fine left/right, but lifts up a short distance only, then is stuck.

    Most of what I've searched on seems to suggest loosening the packing nut. So - I've attempted, and it's stuck so tight that I can't get that thing to turn... so that's most likely the problem - but does anyone have any tricks to get the packing nut to loosen? I don't want to put any heat on it if I could risk damage. I've dropped some PB blaster in there - hopefully that will free it up.

    Another issue seems to be that the lift cylinder will not drop all the way down. The plow hits the ground OK, but the lift cylinder stops there, and doesn't settle all the way in. I'm hoping it's also related to the packing nut, but could something else cause this? Could the packing be blown up?

    Any ideas would be appreciated...

    (oh - specifics, this is the unimount pro plow, with the isarmatic hydraulic pump)
  2. iceyman

    iceyman 2000 Club Member
    Messages: 2,925

    B & B should be chiming in right about .................
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Are you sure its just not low on fluid as to why it will only lift so far?

    The fact that it wont retract the ram any further than it does once the blade is on the ground is normal.
  4. grizbait

    grizbait Junior Member
    Messages: 18

    I will double check the fluid levels, but I am unable to force the cylinder into the housing. I would think it would settle all the way down:confused: Seems like when I initially purchased it, that's what it did...
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Not on its own it won't. The cylinder is ONLY retracted by the weight of the plow pulling it down, it's not a double acting cylinder. They can get rather tight in times of no use so yes they can be difficult to fully retract by hand. Spraying the packings with oil will usually loosen/soften them up as the packings tend to dry out and get pretty tight from lack of use.
  6. grizbait

    grizbait Junior Member
    Messages: 18

    OK - will I'll try to get the packing nut outta there. The parts diagram shows a 'packing set' which I assume has some o-rings on it. Is it typical for that nut to be a bear to get loosened?
  7. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    You can usually work enough oil in there without disassembling it. Just takes a little time.

    And yes the packings are multi piece.
  8. grizbait

    grizbait Junior Member
    Messages: 18

    Alrighty then... I'll give it a go and post back... thanks for the info.
  9. grizbait

    grizbait Junior Member
    Messages: 18


    Unfortunately, I'm going to have to revive this thread.

    So - since I originally posted, I have changed fluids, cleaned filter, checked packing, and loosened the packing nut - and had er going fine most of the season - but still I thought - hey, it seems weak lifting?

    We just had a warm day today, I plowed yesterday, it was slow lifting then, but was doing the job fine - around 10 degrees. But today, it was 45 degrees... and I could barely get it to lift off the ground. Not sure if this is a clue or related to the issue or not.

    Still goes fine side-side, just won't lift (barely) now. Checked fluid levels - and it was fine. Changed the fluid again - still won't lift more than a few inches.

    Is my pump motor going out on me? And is there a way to service it... or test it to be sure?

    (BTW - a sticky on common 'lift' problems for these would be great :cool:)

    Any help appreciated.
  10. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    sounds like weak pump to me. pull the motor off and turn up the pressure 1 quarter turn and see what happens.
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Agreed. TIme to get a pressure gage on it.
  12. Mebes

    Mebes Senior Member
    Messages: 451

    Warm snow tends to stick to the blade making it heavy.
    If it is not raising because of the added weight stuck to the blade, then turn it up 1/4 turn like no lead suggested (main pressure relief valve).

    It does not take as much pressure to turn (angle) the blade as is necessary to lift it.
    So if your blade is to heavy to lift the relief valve will not allow the pump to send enough pressure to the lift ram to pick it up.

    If turning up the relief valve works then get yourself a pressure gauge and set the relief valve to the factory recommended setting.
    If you turn it up beyond that, then you run the risk of burning up the pump.

    By the way every western plow I have ever seen (cable, unimount, or ultramount) I was able to push the piston down by hand (in float)
    If the packing is to tight it is just like adding weight to the plow.
  13. grizbait

    grizbait Junior Member
    Messages: 18

    OK - thanks all, I'll go through the pressure test procedure...