Air in the hydros

[Envy Lawn Service]

I have a new mower that seems to have air in the hydro system. It's not an air lock I don't suppose. The cap stays damp with oil and when I open it I hear an air suction/pressure sound. When I first crank it up, all is fine. But after a while of running, the hydros start pissin and moaning. So today I stuck my jumper wire in the seat safety and hopped off while it was making noise. I opened the cap and I could see very tiny bubbles coming to the surface.

Thinking back I remembered having to tighten the fluid filter the day I got it because oil was running out before I got out of the dealer's lot. I was concerned about air then, but the shop told me not to worry about that.

So anyways, today I decided I should got ahead with jacking it up and bleeding. So I did so. I jacked the rear wheels off the ground. I ran it forward, backward, one side, the other side, high rpm, slow rpm, push valves closed, push valves open. I ran it forever and still I had these very tiny bubbles coming to the surface.

I don't get it...... :confused:

[Green Quality]

what is the make and model of your tractor or ztr? what kind of hydro do you have? I might be able to help!

[Envy Lawn Service]

Yazoo/Kees ZT Max Mini Z
21hp Kawasaki 48" Commercial
Hydro Gear BDP 10L Pumps
Parker Ross TE 14 Wheel motors
Metal high pressure lines
Rubber low pressure lines
Runs on 8 quarts of 20w50

[Green Quality]

If it is a hydro-gear pump.I had the same problem with my cub cadet tractor.change the tranny filter and oil,now the trick is not too over tighten the filter,which will cause the rubber gasket to fold under it self and cause air flow in you tranny,the oil that is called for my cub cadet is called drive system plus syn oil,$10 a Qt,did my home work and found out that hydro -gear used 20w-50 syn motor oil in there pumps.my cub called for 7Qt,so I bought some 15w-50 mobil1 syn,After I changed the filter and oil. I had more power to the rear wheels no more air bubbles,because i think I over tighten the filter on my unit which in turn caused the air leak in the tranny.

[Green Quality]

I hope this helps.I know it bugged the hell out of me.

[Envy Lawn Service]

Thanks.... that could very well be my issue because I operated it with a loose filter, saw the oil leaking down the filter when I trailered it, then checked it by hand. it was pretty loose. So I tightened by hand. Later I got a dribble or two, which possibly could have been oil that had made it past the seal and stayed on top until hot. I didn't think of that at the time though. I just cranked the filter a bit tighter, spit shined it and kept an eye out for more leakage.

[Eric 1]

So you bought a new Y/K?

[Envy Lawn Service]

Yeah, but I don't like to advertise that or for them
Lets just say I refuse to continue to be their 'poster boy' any longer....

[Envy Lawn Service]

I also would like to add that I have not recieved my new filter yet, so I've done diddly so far. One new thing I noticed during this ordeal is that my hydro fluid level is right on when cold. But once I operate it, the fluid level appears to rise in the tank.

It's gotta be sucking air on the low pressure side right? Yet not enough to cause an air lock I guess? Boy I hope it's as simple as the filter seal....

[UNISCAPER]

One other thing to check..........If for what ever rason someone stuck detergent oil in the resevoir, it will bubble and make all kinds of funky sounds. Hydro oil, jack oil, jack hammers, power steering, are all systems that should not have detergent in the oil.

[pfifla1]

oil expands when it gets hot, thats why, you are supposed to leave a few in. at the top of your tank for fluid expansion.

[Envy Lawn Service]

One other thing to check..........If for what ever rason someone stuck detergent oil in the resevoir, it will bubble and make all kinds of funky sounds. Hydro oil, jack oil, jack hammers, power steering, are all systems that should not have detergent in the oil.

Really? I was not aware there was any other non-detergent oil available beyond the non-detergent SAE30....

[Envy Lawn Service]

oil expands when it gets hot, thats why, you are supposed to leave a few in. at the top of your tank for fluid expansion.
Yeah, I realize it expands some when hot... but just how much expansion should you expect? I'm guessing it rises an inch, maybe less, and this is a large reservoir. There is however plenty of room in the tank for expansion before the oil reaches the top.

I'm hoping I'm able to get the filter tomorrow so I can do something....