I know there might be better forums for this, and that may be the help I need, but HEF is my family. I also believe that one out of ten heavy equipment mechanics are JD experts. So my problem is that the large o ring behind the flo control valve spits out. It has been replaced four times now. Some history, we mostly mow with it. One day the Hydrolics start to lose pressure and on this tractor it is a sequence of things stoping. First the three point then PTO then power steering. After letting it sit 20min. every thing works but not for long ant levels and temp are ok. When it is cold as in sitting some hrs. I have good pressure (2100) thinking the pump is good. I read that there is a screen that gets plugged so I put the tractor in my shop and start going through things and yes clogged pickup screen, pin holes in suction line. I use clean oil and filter, replace all O rings. We take it to a job where it works perfectly but the next day it has the same failure after working about one hour I start to lose pressure. Now I take the pump to a respectable hyd house where they take it down,inspect it and replace the seals and washers. We we work it one day and the next day the o ring blows. First o ring was new OE JD, second was local hyd shop maybe a hair to small, third o ring hyd shop much better fit,and last a o ring from my old cheep Harbor freight kit. I do not like pukeing oil all over every other day. Can any one help me solve the problem or steer me in the right direction?
I'll take some guesses that you have both problems ongoing, the hydraulics losing power and the O-ring keeps failing, it wasn't real clear? The only times I've seen O-rings fail repeatedly/quickly is when they move, either the connection is loose and it moves under pressure, or the O-ring gets moved when the parts are put together. Air in the fluid under pressure will work things loose and blow an O-ring. It looks like you have a typical JD closed center radial piston pump. Those are typically fed PRESSURIZED oil from the transmission "charge" pump, and that's where I'd look first. Either check the suction screen again, or the "charge pressure" at the hydraulic pump.
I haven't had any pressure lose since my pump was checked. The o ring sits in a recess, maybe I should resurface the FCV and locktite/torx the bolts? One more time.
Are the bolts tight after it blows? What does the O-ring look like? Definitely torque the bolts, based on the size and grade of the bolt if you can't find a spec. And tighten them in stages, finger tight, then a couple pounds, etc.