I do not have any real experience with hydraulics, but I hope you guys can point me in the right direction. I have an older Brave 24 Ton wood splitter with a problem. After it warms up, it will spit hydraulic fluid out the top of the control valve. I only use the splitter in the vertical mode so the valve is also vertical. At the top of the valve is a flat metal disc with a small cutout (I assume it is for pressure relief) and it is held in place with a snap ring. After about 10 minutes of use it will start to spit a small amount of fluid only on the beginning of the upstroke. That is, when I am beginning to bring the rod back into the cylinder. I do not have this problem when I begin the downstroke. I have no problems splitting wood or with the speed up or down.
I have placed a baggy over the top of the valve with a rubber band and I see it balloon up with hydraulic fluid. It is only a little at first and goes up to maybe .5 teaspoon of fluid at a time. I thought I might need a new value assembly, but wanted to know before I buy the part. Any help is appreciated.

the disc and snap ring covering up the end of the spool bore?
Likely leaking past the spool o-rings.

Remove the spool, there shoudl be square or o-rings in a groove in the valve body. New seals/orings shoudl solve it.

If not mechanically inclined, just replace the entire valve.

or buy the baggies in larger boxes.......

Or take the valve to a Hydraulic Rebuilder and have it resealed. I'm sure they would be happy to have the work.

You can get a brand new Prince kick-off valve (aka "log splitter valve) for $69.99 at Northern Tool. Good price, since we sell them for $129.99 CDN.

http://www2.northerntool.com/product-1/472.htm