Air in the hydros

Discussion in 'Mechanic and Repair' started by Envy Lawn Service, Oct 22, 2004.

  1. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    I have a new mower that seems to have air in the hydro system. It's not an air lock I don't suppose. The cap stays damp with oil and when I open it I hear an air suction/pressure sound. When I first crank it up, all is fine. But after a while of running, the hydros start pissin and moaning. So today I stuck my jumper wire in the seat safety and hopped off while it was making noise. I opened the cap and I could see very tiny bubbles coming to the surface.

    Thinking back I remembered having to tighten the fluid filter the day I got it because oil was running out before I got out of the dealer's lot. I was concerned about air then, but the shop told me not to worry about that.

    So anyways, today I decided I should got ahead with jacking it up and bleeding. So I did so. I jacked the rear wheels off the ground. I ran it forward, backward, one side, the other side, high rpm, slow rpm, push valves closed, push valves open. I ran it forever and still I had these very tiny bubbles coming to the surface.

    I don't get it...... :confused:
     
  2. Green Quality

    Green Quality LawnSite Member
    Posts: 176

    what is the make and model of your tractor or ztr? what kind of hydro do you have? I might be able to help!
     
  3. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Yazoo/Kees ZT Max Mini Z
    21hp Kawasaki 48" Commercial
    Hydro Gear BDP 10L Pumps
    Parker Ross TE 14 Wheel motors
    Metal high pressure lines
    Rubber low pressure lines
    Runs on 8 quarts of 20w50
     
  4. Green Quality

    Green Quality LawnSite Member
    Posts: 176

    If it is a hydro-gear pump.I had the same problem with my cub cadet tractor.change the tranny filter and oil,now the trick is not too over tighten the filter,which will cause the rubber gasket to fold under it self and cause air flow in you tranny,the oil that is called for my cub cadet is called drive system plus syn oil,$10 a Qt,did my home work and found out that hydro -gear used 20w-50 syn motor oil in there pumps.my cub called for 7Qt,so I bought some 15w-50 mobil1 syn,After I changed the filter and oil. I had more power to the rear wheels no more air bubbles,because i think I over tighten the filter on my unit which in turn caused the air leak in the tranny.
     
  5. Green Quality

    Green Quality LawnSite Member
    Posts: 176

    I hope this helps.I know it bugged the hell out of me.
     
  6. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Thanks.... that could very well be my issue because I operated it with a loose filter, saw the oil leaking down the filter when I trailered it, then checked it by hand. it was pretty loose. So I tightened by hand. Later I got a dribble or two, which possibly could have been oil that had made it past the seal and stayed on top until hot. I didn't think of that at the time though. I just cranked the filter a bit tighter, spit shined it and kept an eye out for more leakage.
     
  7. Eric 1

    Eric 1 LawnSite Bronze Member
    Posts: 1,220

    So you bought a new Y/K?
     
  8. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Yeah, but I don't like to advertise that or for them
    Lets just say I refuse to continue to be their 'poster boy' any longer....
     
  9. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    I also would like to add that I have not recieved my new filter yet, so I've done diddly so far. One new thing I noticed during this ordeal is that my hydro fluid level is right on when cold. But once I operate it, the fluid level appears to rise in the tank.

    It's gotta be sucking air on the low pressure side right? Yet not enough to cause an air lock I guess? Boy I hope it's as simple as the filter seal....
     
  10. UNISCAPER

    UNISCAPER LawnSite Bronze Member
    Posts: 1,426

    One other thing to check..........If for what ever rason someone stuck detergent oil in the resevoir, it will bubble and make all kinds of funky sounds. Hydro oil, jack oil, jack hammers, power steering, are all systems that should not have detergent in the oil.
     

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