Tractor Repair: case 2390 no hydraulics, piston pump, hydraulic transmission

Question
After I changed the hydraulic/transmission filters and replaced all the fluid 32 gals. nothing is working. Hydraulics and PS worked briefly then quit. Do you have to prime or bleed any lines. Also the filters looked good but the hydraulic oil looked dirty. Any suggestions?

Answer
Hello,

  There is nothing to bleed, it should prime itself.  It's possible that the charge pump is worn and can't prime once the oil was changed.  But if the hydraulics worked briefly and then quit, it could be that something else failed.  Is the charge pressure warning light on?  If so, the bevel gears that drive the pumps could have failed, or the key in the charge pump could have sheared.  The charge pressure can be checked by putting a gauge in the line between the charge pump and the piston pump by removing the charge pressure warning light sending unit and putting a gauge in instead.  There should be about 30 psi charge pressure.  You can verify that the bevel gears are OK by removing the steering pump from the end of the piston pump and cranking the engine over to see if the piston pump shaft turns.