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Rebuilt hydraulic pump not operating properly

Discussion in 'Mechanic and Repair' started by Shammi, Mar 23, 2014.

  1. Shammi

    Shammi LawnSite Member
    Posts: 55

    I have a Husqvarna IZ6123 61" 23 hp Zturn mower with 500 hours. Last fall, my left Parker hydro pump (H110A2011DDAAX) developed a leak and upon opening it, there were metal shavings inside. The thrust bearing and rotor shaft were trashed. So, I ordered parts and rebuilt that pump and as a precaution opened up the hydro motor as well. The left motor was fine. I didn't open the right side motor at all since it didn't have any problems. I did, however purge all the oil from it by turning a few times by hand. With the hoses disconnected. I also cleaned the reservoir, all the hose lines, removed metal shavings from reservoir and opened the right side pump as well as a precaution. Put it all together yesterday and am not getting the right side (which was good anyway) to turn. Left side (the one that needed repair) seems to be working better.

    The pump that I rebuilt (left side of mower) using new parts is working better than the right side which is now overheating and not turning the wheel motor. The right side was originally fine and the only thing that I did was to open it for inspection as a precaution and put in a new seal kit, but now it is not working. It could be that there is air in the system - I have tried to bleed it by back and forth rocking of control lever, but to no avail. I even took the entire right side pump apart again and reassembled it just to be sure that I hadn't messed it up. It seemed fine - no damaged parts. I also tried to fill some of the lines with hydro oil to minimize air entrapment. I don't know what could be wrong with it. It is not turning the motor much.
    Any ideas?

  2. Shammi

    Shammi LawnSite Member
    Posts: 55

    Maybe I am not bleeding the air from the system properly- since it was completely drained of oil (I mean completely), it may require a specialized procedure for priming/bleeding that I am unaware of. I have tried to rock the control levers back and forth several times at various speeds (maybe 15 separate sets with over 2 hours of engine run time), but no joy. I even left the reservoir cap loose all night to promote bleeding. Nothing worked.
    Any ideas? I really need to get this going in time for the season.
  3. Shammi

    Shammi LawnSite Member
    Posts: 55

  4. Shammi

    Shammi LawnSite Member
    Posts: 55

    What is the purpose of bypass valve on Parker H1 pump?
  5. retrodog

    retrodog LawnSite Silver Member
    Posts: 2,421

    Man lift the mower up, put pumps in nuetral, then work your levers back and forth for a while. Do same thing after you put back in drive. When you took pumps apart did you mark all your plates so you would put them exactly back in the same sequence? It's really easy to make mistakes when rebuilding pumps, I recommend letting a hydraulic shop do it, or just buying new for $499 each....
    Posted via Mobile Device
  6. Shammi

    Shammi LawnSite Member
    Posts: 55

    I lifted the mower. No load on wheels. I marked all plates and assembled them as they were. How do I put the pump in neutral? When I start the engine, the belt drives the pump shaft even at idle speed. As far as I know, it is always in 'drive' - increase throttle and the pump spins faster. Maybe something I need to do with the bypass valve? Thanks

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