Tractor Repair: International 856 wont steer, air leak, rear frame

Question
Power steering, TA, and brakes won't work.  Occasionally they will but quit for apparently no reason.  Have overhauled valve body, power steering control valve, changed oil, and filter. Steering is solid both ways.


Answer
Hello.

  As you may already know, the steering, brakes, and TA are all fed by the same pump which is located behind the multiple control valve on the left side of the transmission.  The hitch and remotes are fed by the other pump on the inside of the rear frame in front of the rear axle.  By valve body, I will assume you mean the multiple control valve.  This contains the pressure regulator, steering relief valve, steering priority valve, TA selector spool, lube pressure spool, etc.  It's not uncommon for a gasket to blow inbetween the sections of the multiple control valve, or to have a leaking sump check valve ( little plastic plunger in the bottom of the valve ).  The pumps will occasionally suck air into the system from a leaking filter cover o-ring or a bad o-ring on the suction tube that feeds the pump.  If all spools move freely in the multiple control valve and there are no blown gaskets, then suspect an air leak.  This will cause it to quit working intermittently for no apparent reason, and will sometimes start working suddenly as mysteriously as it stopped.  Some people claim that overfilling it with oil will help, but I can't recommend doing that.  That's not really fixing the problem, only the symptom.

                          Good luck,

                             Arnie