Tractor Repair: Hydralic problem with loader Ford 3400, shaft seal, hd loader

Question
We have a 1967 Ford 3400 3cyl Gas with a HD loader. While pushing snow in 20 Degree temp. I experienced a hydraulic problem. First I noticed fluid pushing back through the vent at the top of the reservoir which is on the left side and in the loader frame. Also no hydraulic pressure now. I was able to get it home a short distance and parked it. Later I noticed fluid leaking from the pump mounted in front which drives off the front. crankshaft. I checked the lines on both sides of the pump and no leaks, so it appears to be coming out of the pump housing at the bottom. I'm assuming a seal has ruptured within the pump. Its probably time to service the pump either to rebuild it or replace it. My real question is do you have any idea what may have caused this and what may be your recommendations? I'm guessing that the pressure side clogged and back pressure pushed the fluid back into the reservoir. Further the pump seal ruptured? I plan on flushing the pressure side lines to the main control valve, replacing the filter, oil, and servicing the pump? One other note; the pump did have a wining noise for some time. Appreciate any advise you may offer and thank you!!!

Answer
  You won't know for sure until you get the pump off to see what actually happened.  The shaft seal could be leaking, or the pump could be leaking between the sections, or the pump housing could be cracked or broken.  If the shaft seal is leaking and if the pump is not worn out inside, just replacing the seal would be all it needs to fix the leak, but if you have no hydraulic pressure I'm sure there is more wrong than that.  If the pump is worn out inside, then too much oil pressure gets to the seal and causes it to leak or blows the seal out.  If the pump housing is cracked or broken, the relief valve is stuck and caused the pump to build more pressure than it could take when the loader cylinders reached the end of their stroke.  In that case, just replacing the pump only fixes the symptom and not the problem.  If you replace a broken pump without fixing the relief valve, the new pump will break also.  If the pump has been making noise for awhile, it's probably toast and will need to be replaced.  You will know for sure when you get it apart and inspect it.