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Lift piston hesitates towards top of lift stroke.

Discussion in 'Fisher Engineering Discussion' started by gtmustang00, Feb 8, 2015.

  1. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Plow has a new motor (old one **** out), plow worked great, now it's hesitating towards the top of the stroke (friend insisted it was the pump). Did not change. We had installed a new valve a couple months ago as the lift piston would drop slowly (new valve fixed that issue). Friend is frustrated and I'm not quite sure what it could be.
     
  2. NHresident

    NHresident Senior Member
    Messages: 285

    it sounds like the pump is going only way to tell is undo the lift cylinder hose and attach a gauge to it and u watch while somebody hits lift on the controller IF ur getting 1750 psi or better the pumps working as it should IF less u need another pump
     
  3. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Pump is brand new and did not fix the issue.
     
  4. kimber750

    kimber750 PlowSite Veteran
    Messages: 3,669

    Fluid level or pick up tube.
     
  5. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    Put a gauge on it.
     
  6. NHresident

    NHresident Senior Member
    Messages: 285

    if it goes left right as it should and down and im assuming the cartridge u did was the s1 only thing left is some things going on with lift cylinder
     
  7. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Yes s1 was done. The one on the left looking at it from the back.
     
  8. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Put a guage on it 1500psi. And of course the valve adjustments are frozen. Pump was brand new.
     
  9. linckeil

    linckeil PlowSite.com Addict
    from CT
    Messages: 1,265

    does it have a pressure relief valve that can be adjusted? my western does. clockwise a quarter turn is like 225 psi - thats about what you need.
     
  10. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    It is frozen... Don't want to put heat on it as isn't there a rubber o-ring?
     
  11. linckeil

    linckeil PlowSite.com Addict
    from CT
    Messages: 1,265

    frozen as in seized, or frozen as in water in your fluid and actually frozen? i think you are saying the relief value is seized. i can't say i've ever seen that happen as the pump is (or should be) submersed in fluid and well lubricated. it really shouldn't take too much force to move it.

    the only O ring on the pump that i can recall is at the bottom between the pump and the housing at the pickup. i do not think there is one to worry about at the pressure relief valve, but don't quote me on that....

    by the way, what pump is this? an insta-act, or a SEHP?
     
  12. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Insta act. On the passenger side of manifold. The reliefs won't turn. Frozen on a couple of my plows as well.
     
  13. kimber750

    kimber750 PlowSite Veteran
    Messages: 3,669

    Try one of the handheld impact drivers. If that doesn't get heat will be your only option other than replacing manifold. If you do use heat just replace the o rings.
     
  14. navyman

    navyman Member
    Messages: 66

    Sure sounds like a oil quantity issue.
     
  15. gtmustang00

    gtmustang00 Senior Member
    from Berlin
    Messages: 747

    Oil is fresh fisher oil and up to the fill port...
     
  16. navyman

    navyman Member
    Messages: 66

    or as someone else suggested pick up tube or related part is bad or cracked and you are getting some air.
     
  17. superdog1

    superdog1 Senior Member
    Messages: 256

    Here goes a shot in the dark...............If the plow is going left and right without an issue and only messes up at the top of the lift stroke, then maybe you have something bent or binding on the A frame back at the mounting pins? If you are in New England I am sure you have been pushing a little bit of snow the last few weeks Lol. While I like Fisher plows, I would like to find the engineer that decided it would be a good idea to make a pin that is 3" long and the last inch is like 1/2 the diameter of the first 2" and kick him right in the wobbles! Lmao. I have had issues on my MM2 with them, as the holes elongated and had to be fixed. It was giving me issues with binding before I fixed them.