Oliver 770 Oil Issue

[Dakotacornman]

Bought a nice running Oliver 770 last winter. After putting the battery back in I checked the oil and it was very high and ready for a change. Odd. I drained it and prepped for a change. When checking the other fluids I found the little tank up front looking good, but the hydraulic tank was very low. Is it possible that the hydraulic fluid somehow leaked into the crankcase? Have not yet found the leak on the ground.

 

[CoyPatton]

Bought a nice running Oliver 770 last winter. After putting the battery back in I checked the oil and it was very high and ready for a change. Odd. I drained it and prepped for a change. When checking the other fluids I found the little tank up front looking good, but the hydraulic tank was very low. Is it possible that the hydraulic fluid somehow leaked into the crankcase? Have not yet found the leak on the ground.

I am no expert on old tractors, Oliver or otherwise. However I have a question that may provide your answer.
Where is and how does your hydraulic pump work? What drives the pump?

 

[Dakotacornman]

Hard to tell how it all works from my shop manual, but the hydraulic tabk and controls are right in front of the seat, well behind although above the crankcase oil.

 

[Roadworthy]

I don't know old tractors, either. I do know that on some (many?) compact tractors the hydraulic pump is driven by a gear off the crankshaft. If the seal on the hydraulic pump leaks oil can escape directly into the crankcase. There will be no external leak when this happens.

 

[CoyPatton]

I don't know old tractors, either. I do know that on some (many?) compact tractors the hydraulic pump is driven by a gear off the crankshaft. If the seal on the hydraulic pump leaks oil can escape directly into the crankcase. There will be no external leak when this happens.

You hit on the info I was looking for. But I have a friend that has an 8N and he tells me that his hydro pump works of of gears in the differential. I had a distance cousin that passed a few years ago, that could probably have told the OP everything he would ever want to know about his Oliver. He collected Olivers.