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Fisher mm2 pressure relief valve

Discussion in 'Fisher Engineering Discussion' started by 07PSDCREW, Mar 9, 2013.

  1. 07PSDCREW

    07PSDCREW Senior Member
    Messages: 873

    Is it possible for the pressure release valve to go bad? This last storm I noticed when I'm pushing snow (heavy wet) that my blade will turn on its own if I'm pushing hard. Also when pushing if the blade is slightly angled right with a load of snow on it, if I hit left, it dosent have the to push it left and sometimes it just flops all the way right when I'm pushing left. Pump and all electrical work fine all other times.
    Any ideas? I did recently adjust the "quill" that's sticking up hopefully to improve drop speed but that seems unaffected. Since doing that, now I have this new issue.
  2. durafish

    durafish PlowSite.com Addict
    from 02919
    Messages: 1,092

    I think that is suppose to do that my blade does the same.
  3. camaro 77

    camaro 77 Senior Member
    from ma
    Messages: 276

    I had this same thing happen to me last year I was unable to get the pressure relief valve screws out of the alum manifold the screws are steel I ended up changing the manifold block and we then took the whole new block apart and antiseized everything.
  4. 07PSDCREW

    07PSDCREW Senior Member
    Messages: 873

    Durafish..., I know that it is supposed to do it...problem is that it's doing it wayyy to easily. Just pushing a large pile of snow down a driveway on either side of the blade will make it do it.

    Thanks camaro 77 I will look into the block. I'm not exactly sure what I'm looking for but ill try to find the valve.
    That flathead screw sticking up that supposedly helps drop speed, is that the relief valve? Reason I ask Is because drop speed is the same no matter where I turn the screw. Last night I was resting my truck in neutral on a slight incline against a snowbank. Run the blade right and just the weight of the truck would push it back left. I turned that screw back approx where it was before and then the blade wouldn't move when the truck was pushing on it.
    Just curious if that screw is really for drop speed or something else.
  5. unhcp

    unhcp PlowSite.com Addict
    Messages: 1,267

    Yes the quill screw on top of the manifold is the drop speed, I believe the pressure relief valves are on each sides of the block.
  6. camaro 77

    camaro 77 Senior Member
    from ma
    Messages: 276

    they pressure relief valves are on the side of the alum block there should be flat head screws holding in the springs
  7. camaro 77

    camaro 77 Senior Member
    from ma
    Messages: 276

    if the quill screw did not show any signs of change in drop speed you have has a couple different problems going on have you checked pump pressure at all yet
  8. vmj

    vmj Senior Member
    from conn
    Messages: 762

    what would be the other problems? Noticed no change in my drop speed last year....
  9. 07PSDCREW

    07PSDCREW Senior Member
    Messages: 873

    What other problems?
  10. Snow Commandor

    Snow Commandor Senior Member
    from 07666
    Messages: 443

    The crossover relief valves as they're called are located on the 2 sides of the valve body. The quil adjuster on top has nothing to do with the angle function of the plow. Buy the replacement valves and change them out. The package comes with a diagram showing how they go into the block. Just make sure u have a small magnet to remove the springs and balls from the block.
  11. 07PSDCREW

    07PSDCREW Senior Member
    Messages: 873

    Thank you very much for that info ... Ill call the local fisher dealer and see if they have those.