Zg227 - Transmission Fluid bubbles/foaming

[mvan85]

I recently removed the vent/fill cap on the transmission of my ZG227 zero turn, and noticed the fluid was full of small bubbles, and a white foamy look to it. This ultimately goes away after a few minutes, and the machine seems to operate normally, however my concern is air getting into the system somehow, and compromising the fluid, and risking damage to the pump(s).

When I removed the fill cap when the engine is running, there was visible "dancing" of the fluid, jumping up in small droplets, as well as some cloudy gasses or fumes starting to occur. I don't see any fluid leaking anywhere outside of the transmission, so I'm not sure if this is normal, or if there is a leak somewhere. Looking for some insights into what it should look like when you pull the vent/fill cap while the engine is running, and where to go from here.

Thanks

 

[lugbolt]

It's not unusual for them to do that.

If it's severe, like spitting fluid out of the fill/vent cap, check the lines and hoses along the sides of the transmission assembly, and also check the filter for tightness, leak, etc.

if that's all ok, and it's working fine, live with it until it's time to service the transmission. At that point go ahead & change the fluid and filter, and before pouring oil back in, pull the screen out from the back of the trans and clean it off good. Use Super UDT2 fluid, everything else will affect the operation of the transmission including regular UDT.

 

[mvan85]

It's not unusual for them to do that.

If it's severe, like spitting fluid out of the fill/vent cap, check the lines and hoses along the sides of the transmission assembly, and also check the filter for tightness, leak, etc.

if that's all ok, and it's working fine, live with it until it's time to service the transmission. At that point go ahead & change the fluid and filter, and before pouring oil back in, pull the screen out from the back of the trans and clean it off good. Use Super UDT2 fluid, everything else will affect the operation of the transmission including regular UDT.

I appreciate the quick response, Lugbolt! I changed the fluid about 70 hours ago (UDT-2), as well as a new Kubota brand filter, and removed and cleaned the screen filter underneath. Like I said, the machine operates normally, I was just surprised to see the bubbles on the surface of the fluid in transmission case, when looking through the breather opening. I assume there is some pressure in the fluid being returned to the transmission resorvoir. I wasn't operating the control levers, or the deck lift at the time, but the brake was engaged, and it is a wet brake, so I assume that requires some hydraulic fluid to flow through the system. (I'm mostly unaware of how the who Hydrostatic system works to be honest). Does fluid flow constantly, or only when the PTO/hydraulic deck lift/parking brake is engaged?

There is no fluid bubbling out of the breather, or leaking out anywhere that I can see. So it's normal, or not unusual to see the fluid churned up, moving around a bit when looking in the transmission case?

Thanks again!

 

[lugbolt]

actually the brake is mechanical, couple levers run back to each one of the brakes. Not hydraulically operated.

As far as aeration, there are spinning parts inside the trans that rotate as long as the engine is running-this causes some aeration, which is normal.

I think it's ok based on what you are describing. Good job on maintaining it! Most folks don't know about the screen. Those are great mowers.

 

[mvan85]

actually the brake is mechanical, couple levers run back to each one of the brakes. Not hydraulically operated.

As far as aeration, there are spinning parts inside the trans that rotate as long as the engine is running-this causes some aeration, which is normal.

I think it's ok based on what you are describing. Good job on maintaining it! Most folks don't know about the screen. Those are great mowers.

Appreciate your expertise...you helped me out last year with regards to a heat soak issue I posted about for this same mower, and you were spot on about the position of the carb and the heat it's subjected to based on the design of the engine. Idling down for an extra 30-60 seconds really mitigated that issue quite a bit. Have a good weekend!