Great Dane wheel motor/pump issue, part II

Discussion in 'Mechanic and Repair' started by Korey, Mar 31, 2008.

  1. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Here I am again with the same problem and can't seem to figure it out. The left pump is new and as you can see in the pics, doesn't have any leaks but does not work as it should! The right one is completely covered in fluid and appears to be leaking, but is very strong. I can feel a groaning/grinding sound when the left side is under load, however, when the wheels are off the ground, they both appear to rotate normally. Fluid was changed, system was bled, all fittings, bolts, valves, etc are tight. Does the leaky but strong pump have something to do with the completely dry, but useless pump?

    pumps.jpg
     
  2. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Also- the left wheel when jacked up turns a bit faster in both directions than the right when forced to turn by hand. I read that a good wheel motor wouldn't shouldn't allow the wheels to turn in reverse by hand. I have to use some force to turn the wheels but the left definitely turns slightly faster than the right.
     
  3. DiyDave

    DiyDave LawnSite Bronze Member
    Posts: 1,695

    I can't see from your picture, pan the camera right just a little, and tell me if the transport valve is tightened securely. The handle for the valve is visible on the right side of the oily pump, but not the other one.
     
  4. Korey

    Korey LawnSite Senior Member
    Posts: 269

    It's actually on very very tight- I actually need to use pliers to loosen em.
     
  5. DiyDave

    DiyDave LawnSite Bronze Member
    Posts: 1,695

    Sounds like the weak side either has a pump or motor bad. When you are pulling it apart, look to see if there are metal grindings in the hyd system. Also check that the motor shaft is properly seated to the wheel hub, and that the key hasn't been wallowed out. Sounds like you are in for an education. In your area, take components that need testing/rebuilding to advanced fluid systems I think they are based in Lancaster, I know that the shop down here sends units up to lancaster. They saved me about 2/3 the cost from the dealer on a rebuilt wheel motor, the last time I had one done. Good luck!:waving:
     
  6. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Whoa that is defnitely great advice. I always thought it would cost more in labor than in parts, but what you just told me is definitely not the case. I'm suspecting it's the wheel motor but metal shavings in the tank will confirm that. I will also look to see if it's a broken keyway.

    Some questions:

    1- If it's sucking in air, then will air bubbles definitely show up in the tank?
    2- Does a grinding/groaning noise indicate anything specific or can it be symptoms of different things?
    3- Is it possible that the clean pump in the pic is so clean because there is an air lock on that side?
    4- If metal shavings are found in tank, then will pumps have to be replaced as well?

    Thanks a lot for the reply and help- I'm sure a lot of guys as well as myself will benefit from this thread.
     
  7. DiyDave

    DiyDave LawnSite Bronze Member
    Posts: 1,695

    Let me preface this by saying that I have no experience with your particular system, I have only the experience of those systems that I have worked on before. So, to your questions:
    1. The only way it could suck air is if there was a leaky suction hose on one or both pumps, perhaps that is where your oil on the leaky motor is coming from. My suggestion would be to pressure wash the heck out of that side, and operate the machine, as best you can, while looking for the source of the oil, also check all hoses for tightness.
    2. Grinding/groaning noise could be the keyway problem, also could be a similar problem on the belt pulley, or a bent fan blade, or a bad idler bearing. Lots of causes for this one.
    3. External leaks can be symptoms of minor or major problems. Major internal problems can happen with no external leak present. Some more history is needed here. Did you or a dealer replace the pump recently, and was it working for a while? If it was replaced, and never worked since, it could just need bleeding. You do this by simply running it for a while, with the lever for the motor in question in the full on position, till it starts moving on its own.
    4. Metal shavings will sometimes be found downstream of the bad component, best place to look is to start taking hoses off of the weak side. It is possible for a pump to go bad, send metal fragments down to the wheel motor, and either clog the hose, or that, and wipe out the wheel motor.
    Maybe this will help maybe others will know more Good luck.:waving:
     
  8. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Here's what I did:

    1- Inserted a magnet to hydro tank and found no shavings.
    2- Took wheel motor apart and pumped by hand, then reinstalled- no shavings.
    3- Found some loose hydro connections and tightened em.
    4- Top and bottom bolts on left side arm were loose, so I tightened em.
    5- Bled system, then took for a spin-worked great, shut it down to put mower belt on, took for spin again, the problem came back.
    6- Took belt off thinking maybe it had something to do with the problem, but it didn't do anything.
    7- Found leak near left wheel motor and tightened it, bled again, tested mower- still no change.

    Starting to go crazy here. There are no bubbles in the tank so I'd be suprised if it was sucking in air. Nobody wants to pressure test the machine and if I take it to a dealer they are not gonna know what the problem is and end up replacing both wheel motors and both pumps, then charge me a fortune. When I bleed the system, the left wheel doesn't respond as well as the right and seems to visually click in low rpm.

    The funny thing is that it has the symptoms of a bad wheel motor and sucking in air but there is absolutely no evidence to show that (no shavings, no air bubbles).
     
  9. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Ok just rode it again and the right side pump (the dirty, but stong side) is leaking out of the dump valve. Does this make any sense? Would this cause the left side to not function as it should even though the right side is good?
     
  10. Korey

    Korey LawnSite Senior Member
    Posts: 269

    Update- found a wheel motor on ebay and sent my pump to be rebuilt. Put everything back together and now it works like a charm. This was months ago but thought I may as well post an update. Thanks to everybody who helped.
     

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