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Symptoms of a dying hydro pump?

Discussion in 'Mechanic and Repair' started by freerange, Oct 2, 2009.

  1. freerange

    freerange LawnSite Member
    Messages: 4

    I'm in the process of rehabbing a 52" Wright Stander and had a few questions...

    I picked up the machine cheap because it had issues with the right side hydro drive. Closer inspection revealed a bent hub and wasted wheel motor. I replaced both parts and now have a functioning mower. My only issue is when I try to attain speeds above 25%, I get a stuttering noise and feel from the right side. It seems to be coming specifically from the lines connecting the pump to the wheel motor. You can hear it there and feel it if you put your hand on them.

    When I give it more than 25%, it stutters and loses power. I noticed this while trying to load it into my enclosed trailer to move it from one shop to another. I got 1/2 way up and the power to the right wheel just faded. Is this normally the symptom of a dying/dead hydro pump?

    My first thought is cavitation, but why would everything be perfect below 25%? When the motor was replaced, I flushed the system and replaced the filter. I manually bled the air from the wheel motor prior to reassembly, and then followed the standard way of bleeding the hydro pumps while I still had it on the lift.

    BTW- this is more or less a side project I'm working on with hopes of adding it to the fleet someday. The left side already has a new pump & motor.

    Thanks for any ideas.
  2. silverado212

    silverado212 LawnSite Senior Member
    Messages: 373

    Sounds like you just need to match the pump and wheel motor on other side. You did all I could think of.
  3. Cboy7

    Cboy7 LawnSite Senior Member
    from Fl
    Messages: 386

    bleed the lines ,... sounds like air in the hose
  4. Tharrell

    Tharrell LawnSite Silver Member
    Messages: 2,967

    Probably air but, check the belt to the pumps also. Tony
  5. gene gls

    gene gls LawnSite Gold Member
    Messages: 3,213

    My Hustler S/Z was starting to have a simular issue and I switched over to the 20-50W oil and its like a new machine, for a while anyways.
  6. freerange

    freerange LawnSite Member
    Messages: 4

    Thanks so much for all of the info guys...

    I'll try working my way up from the wheel motor and cracking each connection in the lines looking for air. I'll do the same from the pump upwards also.

    The belt is new, but I'll pull it again and check the tensioner and right side hydro pulley. A friend also suggested a physical blockage in the lines connecting the pump to motor. It appeared as though the mower suffered some sort of physical "trauma" like it was hit in the right wheel by something causing the hub to bend. At that point, some genius decided to just run it like that, mangling the wheel motor (the teeth on the shaft inside were 90% ground away). Maybe something got caught up in the lines and the flushing just isn't enough to free it?

    I'll try your suggestions and update as it goes. I might try the heavier oil too...

    Thanks guys,
  7. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,074

    Take one guess where all those splines went. The pump has to come apart to be cleaned
    (or replaced). Flushing, for a failure you describe, is a waste of time. And the system is self bleeding - if the components were pre-filled before assembly.

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