Bobcat 773 leaking Hydraulic fluid into Gearbox

[BamaGN]

First off, thanks for any help with this. I have a bobcat 773 I bought last year to work around the house. I have been chasing a lot of gremlins with it, like bad computer, leaking hoses, leaking wheel seals, etc. I now have all the leaks fixed and noticed the top of the 3 gear box covers were leaking. So I ordered new seals and replaced them. I did not know at the time it was overfilled.
So my issue is when I add hydraulic fluid to the recommended level, it leaks down to the gearbox and fills it to the top. It usually takes a week to leak down. I don't know where to begin to chase this issue. I have looked for how the fluid travels through the system, but cant find anything. Again, thanks for any help.

 

[brdgbldr]

There is a seal in the motor carrier that causes this. It keeps oil from going from the motor into the chain case. They are normally pretty easy to replace but the motor has to be removed.

 

[BamaGN]

On the diagram below is #7 the correct seal? Is there just one motor carrier? Thanks so much for the help.

 

[brdgbldr]

If you got that diagram from: https://www.bobcatpartsonline.com/#/catalogBrowser
and entered your serial number, then yes, that is the correct seal.

There are two motor carriers and two motors. One on each side of the machine. I would suggest replacing both at the same time.

 

[BamaGN]

I will replace both. Thanks for your help.

 

[Land-Tech Custom Landscap]

I had this happen to mine and it almost drove me crazy!! This will sound out of this world but my problem was a bad hydraulic hose coming from the chain case filter. Brdgbldr is correct that it is the seal going bad so I replaced mine. Sometimes it would last 20 min, sometimes it would last weeks, but eventually it would fail again. I replaced all of the o-rings in the carrier, nope, that wasnt it, and every time it did this it would pump $50-100 dollars worth of hydraulic oil into the chaincase. UGHHH I was going crazy and every bobcat mechanic knew they had the answer but none ever did. Finally this old mechanic said that the seal is a 2 sided seal and that mine was building up pressure on the outside and pushing it in. He said check that tiny hydraulic line on the top of the carrier and see if it is blocked or clogged. I said no way, its brand new.....Guess what, the brand new hydraulic line coming from the chain case filter down to the carrier that was brand new, they had over crimped the fitting. This would not allow the oil to flow through the line, it would build up pressure against the seal and eventually blow it out (or actually in). I took the lines off and just tried to blow through them, thats how I found out which one it was. I replaced the line with another new one and have not had a problem since.

 

[BamaGN]

Thanks for the advice. I will check that too. Been too busy to install the new seals, but I will definitely check this out.