727 Rebuild Woes: Oil Pump stator / drum air leak

I took a look at an exploded view of the 727. First, check all the scarf cut rings and be sure they are floating freely in the grooves, and the ends aren't jammed together. If you replaced scarfs with the steel 'clasp' type (not sure the true name) rings, make sure they are locked/snapped together at the ends. (stator)

I would rebuild the pump as well while its out. Just to be sure that the two halves, or the stator/pump are not 'clocked' incorrectly. Causing Obstructed passages or venting them to atmosphere. (leaks) Or just clogged with trash from a failure.

There are two large lip seals in the direct drum on the 727, an inner, and an outer. The forward drum has both these seals as well. Check that you did not mix the seals up between the direct and forward drum sets. Additionally, the lip seals are often an "L" shape. I believe that they need to be installed in the correct direction. The large diameter outer seals need to have the 'lip' or 'skirt' of the seal protruding towards the 'thin' side of the piston in relationship to the groove, for both the direct and forward drum. The inner seals 'lip' direction should mirror the outer seals, so all seals face the same direction after install. Not getting this right will cause a drum leak for sure during clutch engagement.

I believe there is a seal on the direct hub as well, that engages with the direct drum. I think it is accessible without removing the shaft from the hub. its out of the equation with a bench test. But, I would just check that too while you are at it.

If I remember correctly I had to install my pump into the direct drum (on the bench) and rotate it around a few times to help seat the rings and then air check on the bench.