7020/40 Oil Transfer

I know Mack talked about the seal on the hydraulic pumps drive shaft as pretty much always his fix. I myself don't ever remember fighting a rear end to tranny oil transfer situation. Mine have always been transmission disappearing into the rear end and that was always related to the gerotor pump to gear pump seal or bad pump bushings/bad pump. I did have one 7080 back in 1979 that another dealer had just recently been in the rear end and had that upper PTO seal in backwards. It would transfer oil when running it down the road and didn't seem to bother in the field. Do you think your transfer occurs only when using the tractor?? or might it slowly transfer sitting in a level shed??   I guess if you drained the tranny completely and left a clean 5 gallon pail under the trans suction screen for a week, you'd know if the rear end was going down and the 5 gallon pail was gaining. That would then get down to the pump drive shaft seal and bushing (you could actually see it) or the pinion seal or the large core plug inside the range transmission floor. A plugged breather to the rear end (the fill cap) I suppose is a possibility, so I'd leave it removed for this gravity test. If the fill cap was plugged I could see it allowing pressure to build in the rear end maybe forcing oil to push thru the pinion seal ?? especially when in the field and hot.   EDIT:  I know on the gerotor pump seal, I always had to wrap the splines with a thin spirol layer of black tape and oil it, to slide the new seal over the splines to not damage the seal. I don't remember the pumps drive shaft design if it is also prone to seal damage when sliding it on over the splines or not. You kind of made mention that repairs had just been made to each of these tractors and then they started transferring oil?????     I know for a fact there have been times when black belly tractors have had hoses and lines crossed up ahead of the radiator causing this.

Edited by DrAllis - 7 hours 15 minutes ago at 9:29am