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Motor runs, no lift or angle

Discussion in 'Fisher Engineering Discussion' started by MarkD65, Nov 23, 2010.

  1. MarkD65

    MarkD65 Junior Member
    Messages: 3

    I bought a 7 1/2' MM1 used last year and used it for the season. The maintenance manual says you should change the hydraulic fluid annually so I decided to do it today to get it ready for the season. I figured I would hook the plow up to my truck before changing the fluid. After mounting,I went to raise the plow, the motor wined, but the plow would not lift. The same was true for angling. It was working fine when I disconnected last year, any idea what may have gone wrong?:cry:

    Thanks for the help!
  2. Arc Burn

    Arc Burn PlowSite.com Addict
    Messages: 1,141

    Drain the fluid and check your filter,i'll bet it's clogged,condensation does crazy things to the insides of these units
  3. fx4plowin

    fx4plowin Member
    Messages: 47

    is it a constant motor running, as in motor runs without pushing any buttons on the controls?
  4. Philbilly2

    Philbilly2 PlowSite Veteran
    Messages: 3,770

    Check your grounds going to your coils on your directional valves. If the motor runs, but no valves will open, commonly a gound issue.
  5. ma71t

    ma71t Junior Member
    Messages: 3

    Same Issue here almost exactly i got one lift out of it to move the plow then the same symptoms started.... I have:

    Checked all grounds
    checked all solenoids
    checked poppett valves
    everything is all set, i guess now i have to check the pickup screen and pump output pressure
  6. equip guy

    equip guy Member
    Messages: 38

    What happens now, no lift again after 1 pick up
    Can you see the plow jerk in the direction of where you select it?
    If you jacked it up a little, can you move the plow at all?
  7. ma71t

    ma71t Junior Member
    Messages: 3

    nothing happening just motor running no jerking no nothing.... damn plows just replaced it with a x blade anyway but i need to fix it to sell it and recoup some of my costs
  8. MarkD65

    MarkD65 Junior Member
    Messages: 3

    Thanks for the help! I got the plow running.
    I'll go through what I did in case it helps somebody else out. The reason I hooked the plow up was to change the hydraulic fluid. I found it wouldn't move. Instead of draining it I pulled the resevoir off the bottom and dumped the oil out. Next I pulled the filter off and cleaned it and the resevoir out. It was dirty (oil left in it wouldn't leak back out of the filter, and there was sludge at the bottom of the resevoir). I put it all back together with high expectations, still didn't work.
    Next I opened each of the hydraulic lines one at a time and tried to activate the circuit with the control to see if the fluid was entering the hoses, none was.
    Next I measured the resistance of each of the 3 solenoid coils, all 3 were about 7.5 ohms. So they were good. I pulled the coils off, and then removed S1, S2, and S3. They looked ok externally. Next I inserted something blunt into the end of each of them and pressed down to see if the spring inside would compress, they didn't. I pressed a little harder, it broke free and compressed. This was true for all 3 solenoids. I reassembeld everything and voila, the plow now works.