1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Hydraulic pressure

Discussion in 'Truck & Equipment Repair' started by 3seasonguy, Dec 28, 2011.

  1. 3seasonguy

    3seasonguy Junior Member
    from cen ma
    Messages: 4

    Looking for some assistance with a SEHP Fisher MM. Motor is spinning but no hydraulic pressure. Recently replaced motor and changed fluid.

    I was getting this same problem towards the end of last season.. low or no pressure, slow blade movement. I thought it was the motor so I was surprised that after replacing it, the problem is worse.
    Thanks in advance.
     
    Last edited: Dec 28, 2011
  2. kimber750

    kimber750 PlowSite Veteran
    Messages: 3,686

    Is this insta act or sehp?
     
  3. 3seasonguy

    3seasonguy Junior Member
    from cen ma
    Messages: 4

    SEHP Fisher Unit
     
  4. kimber750

    kimber750 PlowSite Veteran
    Messages: 3,686

    If it is two post motor make sure pos and neg are not backwards. If wiring is correct could be pump itself, clogged filter or pump relief valve. I would start with the filter.
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Can be a blown O-ring under the pump too. Fairly common on the SEHP units. Could have pulled the pump out and checked the O-ring under it while you had the motor off.
     
  6. 3seasonguy

    3seasonguy Junior Member
    from cen ma
    Messages: 4

    Actually, I just realized that it is an Insta act unit...sorry.
     
  7. TJS

    TJS PlowSite.com Addict
    Messages: 1,344

    Ok now that you know which pump you have, get yourself a filter and service kit along with new fluid. Remove the fluid resiviour and you may notice the pickup tube or the filter has fallen off. Clean everything out, all the gook and stuff. I find it easier to remove the pump from the frame and get it on a work bench. I also power up the motor and set the pickup in fresh fluid and power the pump up and flush it out. I also follow the procedure for flushing out the rams. You can download the fisher manual at fisher.com
    T.J.