Scag Tiger Cub Hydro problem

Discussion in 'Mechanic and Repair' started by William Graziose, Sep 13, 2017.

  1. William Graziose

    William Graziose LawnSite Member
    Messages: 3

    I searched the forum and can't find the exact problem I'm having.

    I have a scag tiger cub 48 " deck

    Recently, when sitting in the machine, the left handle and wheel became very weak and not keeping up pace with the right handles wheel. The past two days once you run the machine for about 15 mins you basically loose all power in the left handle on any kind of decline or incline.

    What I have done so far: rebuilt hydro pump (all seals). When I opened the pump there was no metal shavings or other wear. The valve attached to the handle seemed to move freely without problem. Changed belt. Changed tension spring. Purged the system and I made sure 5/8 hex nuts r tight again.

    There is a hydro leak near the filter. Is there any chance this is drawing in air?

    Please any help on what it could be, im praying it's not a wheel pump (which I don't think it is because when I purged it, it moved freely without any noise for 10 mins) or hydro pump cause there both big money.
  2. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,120

    Could be, best get it stopped before ya move on, right?
  3. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,092

    What valve on the handle? Were the pistons in the cylinder block free? Is the trunnion/control shaft tight?
    Is there any sign of aeration in the oil tank?

    And yes, as Fish says, fix the leak. Always fix the obvious, unless you have experience / knowledge of the system you're working with.
  4. William Graziose

    William Graziose LawnSite Member
    Messages: 3

    So sorry for the delayed response, been busy and machine has been sitting. I finally have free time and started ripping into it again.

    First thing I did was fix all visiable leaks. Next I changed the block kit and valve plate. Control shaft is tight. I opened up the resavoir and didn't see any bubbles. machine ran great for about ten minutes, then same problem happened. It started loosing power in the left to where it almost didn't move on that side.

    Side note I noticed resavoir was extremely hot, also if you pulled the left handle back to start going in circles it takes about 5 seconds to get going and even then isn't as quick or with the same power the right side has.

    I'm thinking the wheel motor, only thing that is stumping me is why it runs greAt cold then looses power. Is there any valves that need adjusting once engine heats up or possibly missing something stupid when I put it back together
  5. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,092

    Did you have the shock valves out? That "might" cause a problem if the were reversed. There's also the small ball and spring in the charge pump on top. The oval shaped part.
    The oil is much thicker when cold. Has a better sealing effect on components. Oil temp runs approx. 180~210 degrees. Many variables on that. The pump should be tested with a flow meter. Do you know a competent shop? They should be able to do it within a 1/2 - 3/4 of an hrs. That will tell you if it's the pump or motor. Usually they aren't needed, depending on experience. Motors are VERY expensive. Even more so when they're replaced when not needed.
    Of course the tow valve is closed?
  6. William Graziose

    William Graziose LawnSite Member
    Messages: 3

    Shock valves are correct and the tow valve is closed. There's no visiable leak coming from the wheel motor. With that being said, would it be smart to rebuild it? (I rebuilt a wheel motor that had a bad bearing, but it was leaking) without a leak does that mean an internal part is damaged most likely or could it be new o rings and bearings are causing a compression problem
  7. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,092

    Usually it’s not worth it. There’s no way to “check” a wheel motor for performance. You can take it apart and check the gerotar area. They fool me every so often. I’ve been at a dealership for too long LOL
    That’s why I say, if you can check the pump performance via a competent mechanic testing with a flow meter, then it becomes a process of elimination. Thats about all I can tell you.
    If you have no foam in oil tank, no visible leaks, and it’s plumbed correctly, with no strange or excessive noise.
    What’s left? I have seen wheel motor literally pump oil out and still drive with power. The only reason they fix them (I replace them) is they kill grass with the oil. Hydro oil, from what I understand is worse than gas on grass. Only what I hear. I dont cut grass. Maybe when I pack it in and start making some serious coin LOL
    JLSLLC likes this.

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