Tractor Repair: IH 300 utility power steering failure, power steering failure, crankshaft pulley

Question
Dear Arnie,
  We have an IH 300 utilty tractor with a loader attached.  When it was put away for the winter, the power steering worked.  Now when we brought it out it doesn't work. The loader works just fine.  So we know that it's not the hydraulic pump. I tried to look up the power steering pump diagram on CNH's website to get an idea what the internal guts look like, but had no success.  My husband and I are quite app at fixing tractors.  Should we put a presure guage in the hyd line going into the power steeing pump?  Is there such a thing as the power steeing "pump" loosing its prime?  If so what do we do?  Any suggestions would be appreciated before we tear the pump off.

Answer
Hello,

  Depending on what kind of loader you have and how it gets it's hydraulic supply, the loader might be running off a separate pump.  Some loaders have their own pump that is driven by a shaft attached to the front crankshaft pulley of the engine, and the pump sticks out in front of the grille of the tractor.  If your loader does not have this pump, then it is running off the tractor hydraulic pump.  There is no separate power steering pump on this model tractor.  Everything runs off the main hydraulic pump that is mounted onto the side of the engine.  The oil goes from this pump into a flow divider valve either under or on the side of the seat.  The flow divider sends some oil to the power steering, and the rest to the remotes and the rear hitch, but steering is supposed to get priority over the other functions so you don't lose steering while operating them.  I have seen a pump that was airlocked on one of these once, so it's not impossible.  I loosened the discharge fitting on the pump until the air came out and it started to work, which shot oil all over the place until I got the engine shut off.  It's also possible that there is a spool sticking in the flow divider valve.  If it worked OK when you put it away and doesn't work now, then the problem is not going to be the pump itself so don't take it off.  Not sure where you can put a gauge in to check pressure without seeing it.