Tractor Repair: case/int model 585, piston seals, master cylinder

Question
Sir: Lost left brake.. right brake still works. is it the
left master cylinder? if so how do i test it..?
Or is it bleeding into the transmission on the left rear axle?
how do i check that?  thanks,  gmo

Answer
  It could be the master cylinder, equalizer valve, or the brake piston seals so you will have to narrow it down.  Make sure the right brake pedal comes all the way back up, otherwise it will hold the equalizer valve open and affect the left brake.  Bleed the left brake with the engine running until all the air comes out.  If you keep getting more air no matter how much you bleed, the piston seals in the rear axle are leaking.  If you can get all the air out and get firm pedals, try applying both brakes at the same time.  If the pedals hold and don't fade, the master cylinder and piston seals should be OK.  If you can't get a firm pedal or if you keep losing the left brake, try capping off the brake line to the left brake.  If the pedal is firm, the master cylinder is good and the piston seals are leaking.  If the pedal still is not firm, the master cylinder or equalizer valve is leaking internally.