Hydro system problems

Discussion in 'Mechanic and Repair' started by carguyrob, Apr 17, 2013.

  1. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    I have researched this to death and the only solution I have found is that it could be anything, so any advice or pointers are welcomed! I have a scag wildcat with about 2000hrs on it. I took the left side wheel motor apart to replace the seals as it was leaking fluid at the end of last season. Everything went fine in the disassembly and reassembly of the unit and it no longer leaks. The only problem is the left side is lacking power. Going up hills it is almost useless and starting the left wheel from a stop I would describe as notchy or hesitant. On flat ground it runs almost normal, and the cooler the system the better it runs. I figured it was an air pocket but I have tried purging the system the recommended way 3 times now and it seems to do nothing with no air showing up in the resevoir. I filled the wheel motor with oil during and after reassembly and did a full fluid change with filter (which I also filled with oil prior to installation). The other side functions perfectly, and both pressure release valves are tight. Sorry for the long winded post! Any ideas? Thanks
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024


    Just curious...... Describe the "recommend" way ?

    Is the hydro belt in good condition and tensioned properly ?

    Make sure your hydro lines are tight, They can suck air without leaking oil.....
     
  3. dieselss

    dieselss LawnSite Bronze Member
    Posts: 1,549

    Was it doing this before you tore dwn the wheel motor?
    What weight oil are you running in it
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  4. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    I jacked the mower up and opened the release valves and moved the controls back and forth for a few minutes. I did check the belt and tensioner and both appear to be fine. The right side runs perfectly. The only lines I removed are the 2 going into the wheel motor and I doubled checked them yesterday, they are tight. If there is air in the system is it possible it would only affect the left side?
     
  5. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    The hydro's weren't 100% before I tore it down, but it had no problems going up any hill I wanted it too. I had noticed over the years the ground speed doesn't seem to be what it used to, but never any shortage of torque. I am running 20-50 amsoil in the hydros.
     
  6. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    Also, after running the mower all day yesterday, the problem definitely gets worse as the fluid heats up. Cold off the trailer it runs pretty good, but by the end of a 4 lawn stop I did yesterday I needed to push the left lever almost all the way to get it up the trailer.
     
  7. dieselss

    dieselss LawnSite Bronze Member
    Posts: 1,549

    Id say pump. But are all the seals in the proper ways. Are they all the same sizes etc...
    Posted via Mobile Device
     
  8. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    In the wheel motor there were 2 or 3 different sized seals. It was pretty obvious where they all went, I had the service manual too. Is there a way to test the pump? I wish the parts weren't so expensive, just don't wanna buy stuff I don't need. Thanks!
     
  9. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Try purging by leaving the bypass valves closed, Run throttle at about 3/4's then move sticks slowly full forward then full reverse. Do this 8-10 times back and forth slowly and see if it makes a difference.

    You need a fluid flow meter to test hydro pumps, Their in the $350-400 range in which is why some smaller shops don't have one......
     
  10. carguyrob

    carguyrob LawnSite Member
    Posts: 204

    I will try that today. Do you think it will make a difference since mowing with it hasn't? I figure all my maneuvering is pretty much purging with the valve closed. The fact it gets way worse with hot fluid has me wondering. Thanks for the help
     

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