Tractor Repair: 5250 brakes, piston seals, wheels and axles

Question
I just rebuilt the master cylinders on Case IH 5250 thinking that was the problem with the fluid leak down out of the reservoir.  Wrong guess.  I can bleed the brakes and they will be fine for about a day.  Then the fluid in the reservoir will be gone and no brakes.  Is there a check valve in the feed hose? What am I missing?  Thanks for any help.

Answer
Hello,

  There is no check valve in the supply hose, but some models have a small orifice inside the hose that if restricted, would cause it to not keep the reservoir full.  However the problem of the fluid leaking down if the tractor sits for a day or so, is caused by the fluid leaking past the brake piston seals inside the rear axle.  Unfortunately, to replace the piston seals, the rear wheels and axles must be removed to get at the brakes.  To verify, the brake lines can be disconnected and capped off.  If the fluid has not gone down after sitting overnight, then the piston seals are the problem.  But if there are no external leaks on the brake lines and hoses, the brake pistons are really the only other place the fluid can go.  And it's not an uncommon problem either, I just fixed one last spring.

                   Good luck,

                        Arnie