Gravely 44z hydro problem

[sstumpf]

I am having a problem with my gravely 44z zero turn, it is not wanting to move forward or back. so i replaced the hydro fluid and drive belt. jacked it up and ran it forward and back to bleed any air out. dropped it back down and it moved both ways just fine, so i thought it was fixed. now 24 hours later same thing, it does not want to move either way. when i jack it up to take the weight off it moves the tires really slow. any ideas on my next step? thanks.

 

[RandyT]

Assuming that you have two separate drive units it seems odd that both would go goofy at the same time. My first suspicion is a damage drive unit, but that wouldn't normally effect both sides at once, unless the other side was also going bad, but you didn't notice it until the second unit failed. Jack up the rear of the mower and release the parking brakes, and with the bypass is the drive position(there normal running position) see how easy you can turn the wheels. if they are really hard to turn or impossible to turn I would say that unit is Ok as far as the hydraulic motor side of the unit. if the wheels turn easily then the drive is toast and will either need repaired or replaced.

I am currently waiting on parts for a hydrogear unit out of hustler that damaged the drive motor, drive pump, the center section. The charge pump, and cover, as also scored the bottom cover for the tranny unit that the charge pump runs against.

 

[sstumpf]

ok, well both wheels are easy to turn when jacked up. but what is odd is that when i replaced oil and belt it worked great, but the next day it was back to doing the same thing. any chance I have a bad fitting or hose and its sucking in air?

 

[RandyT]

Sucking air would cause cavitation. It would still move, but be very jerky.

I am assuming that you have separate completely contained drive units for each wheel, and not separate pump and drive wheel motors If you have the pump and wheel motor setup connected by hoses, then the whole system could be toast due to damage to one of the components sending shrapnel through the rest of the system.

 

[sstumpf]

ok. I have the separate pump and drive wheel motors that are connected by hoses. hmm, I guess the whole system could be messed up, its just odd, it wouldnt move, so i replaced belt and fluid, it worked that night just fine, then next day it was back to not working.

 

[sstumpf]

Also, when it is jacked up the wheels spin at almost full speed, but as soon as I let it down and put the weight back on them, it wont move. on the low pressure line between the filter and the 2 hydro pumps where it tees off, There is quite a bit of fluid build up there, almost looks like a leak.

 

[sstumpf]

this is the part im talking about Gravely Part , HOSE- TEE ASSM .38 | PartsTree.com

the back side of the tee has fluid running down it, as well as the left yellow rubber ring is cracked and fluid is starting to come out around that.

 

[RandyT]

Any leak between the oil tank and the pump will cause a vacuum leak when running. That may be the reason that you lost drive after setting overnight. You have air in the system introduced by the leaking suction line. that will need to be repaired before further testing can be done. When you have separate pumps and drive motors fed by a single oil storage tank, any shrapnel from one failure will migrate to the oil tank and then get distributed to the rest of the system causing failure of those components also.

 

[sstumpf]

Ok, I will get that fixed and go from there. Thanks for the help, I will post back when i get the leak fixed this weekend.

 

[sstumpf]

Got the hose replaced on Saturday, and everything is back to normal, think it fixed it.