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  1. #1

    Default Hydrostatic Transmissions

    I have a Chraftsman Lawn Tractor with a Hydrostatic Transmission that sounds like its bypassing fluid or passing air through the system. When this whine like noise is occuring the tractor looses its power going up hill and free wheels (overspeeds) going downhill. After it operates like this for about 1/2 hour it will correct itself and run normal. Any suggestions as to what repair is needed.

  2. #2

    Join Date
    Jul 2004
    McHenry, Illinois - Right up near Wisconsin
    New Holland TC40DA

    Default Re: Hydrostatic Transmissions

    The obvious place to start - have you checked the hydro fluid levels? How about a clogged filter?


  3. #3
    Gold Member
    Join Date
    May 2004
    Near Edmonton, Alberta, Canada
    John Deere 990 4x4

    Default Re: Hydrostatic Transmissions

    Unfortunately, I think all these small hydros are sealed units (I've got one too). No way to change filters, check or add fluid, etc. I guess they assume a garden tractor doesn't see hard enough usage to worry about it, or that the average garden tractor owner isn't smart enough to handle things like fluid checks (dumb assumption [img]/forums/images/graemlins/mad.gif[/img]).

    Anyway, the procedure for bleeding air out is to first put the transmission in free-wheel mode. On mine there is a metal rod you can pull out and latch, or let it pop back in by spring pressure. It is located at the rear of the tractor by the right wheel. If I remember right, the hole the rod comes through is keyhole shaped and you pull the rod out until a collar comes through the wide part of the hole, and then push it down into the smaller part of the hole to hold it there (this is just holding the internal relieve valve open I think). Once in free-wheel mode, start the tractor up and slowly push the forward and backward pedals to full travel several times. Release the rod to get out of free-wheel mode and try it out.

    If bleeding the air out doesn't help, there probably isn't much choice but to take it in and have it looked at. As I said, these are usually sealed units and even checking the fluid would require some major disassembly which might be more than you want to get into.

    Good Luck

    ps. If you work it hard and get the transmission hot (I have many hills), my garden tractor will lose power too. This is just from the fluid thinning when it's hot and slipping too much past internal clearances. This is annoying, but fairly normal I think. All is well again when it cools off. I don't notice any unusual whining when it's doing this, however, so that may not be what you are experiencing.

  4. #4
    Veteran Member
    Join Date
    Mar 2004
    Central Ma.
    7275 Cub Cadet

    Default Re: Hydrostatic Transmissions

    Is your rear end a Sullivan by any chance? My MTD as a problem climbing hills in fast mode. It works fine if you back off the lever. I hope to tear it down this winter and see what makes it tick.

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