I have a 1972 727, stock except for a Transgo TF-2 kit. It was rebuilt last winter, developed a small leak in the spring once I began driving the car, that was either the vent or input shaft seal.

Transmission has been out, input shaft seal and bushing replaced, still leaking. Confirmed to be the vent but it has the right amount of fluid in it, drained converter and filled from empty.

Does anyone know what can cause enough pressure, in park, for fluid to come out the vent? Car is on a level surface.

At this point, we are absolutely sure of:

1. Fluid is not overfilled.
2. Leak is from the vent, not the converter hub or input shaft seal.

Thanks in advance,

Mike.