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monarch m-3551 pump in a 1ton dump

Discussion in 'Truck & Equipment Repair' started by t.i.b, Feb 6, 2015.

  1. t.i.b

    t.i.b Senior Member
    Messages: 140

    does anyone know how to change the motor on the pump? I don't see any bolts that hold the motor to the pump? I have the new motor and cant for the life of me figure out how to swap them.
    thanks
     
  2. t.i.b

    t.i.b Senior Member
    Messages: 140

    So i think the motor may not be the problem.(still wondering how to change it though). Now I think its just iced up. does anyone know how to change the fluid? Are there filter(s) in there? cant find a drain plug, so im gonna siphon out what I can fill with new fluid crack the line on the cylinder and run till I get clean fluid. Unless some one has a better idea,
     
  3. Herm Witte

    Herm Witte Senior Member
    Messages: 553

    Most monarch pumps have two long bolts attaching the motor to the pump. They are found on the end cap of the motor. The oil reservoir is attached to the pump with several screws. Yes there is a small screen in the reservoir. If this unit is old and working ok I would not take it apart and just siphon the fluid out. In our history of working with electric hydraulics we have found that most often when the electric motor goes bad the pump is not far behind.
     
  4. t.i.b

    t.i.b Senior Member
    Messages: 140

    ok. I thought the 2 long bolts held the guts in the motor, like in older starters. the dump body is acting like a plow that has ice in it. Its in a 2004 truck so I assume the pump is the same age. ive got a hair dryer on it to try to warm it up but so far no luck. ive siphoned out what I could for fluid but no luck with getting it to work correctly it goes up & down just very slowly with a lot or battery drain.
     
  5. Herm Witte

    Herm Witte Senior Member
    Messages: 553

    A pressure test will tell you if the pump is ok and your issue is the result of a bad motor. Given that it is ten years old, I would not even mess with a motor I would replace the entire unit. A hydraulics shop would likely help you test the pressure.
     
  6. wahlturfcare

    wahlturfcare Senior Member
    Messages: 320

    Also check your hinges on the dump body as I have had one dragging before to cause the same symptoms. And also make sure the lift cylinder isn't dragging on the seal as it will cause it also. Those monarch pumps have a check valve you can adjust to speed it up too. And each coil should have a scree. On them. You might try. Cleaning them also.