914 GEARBOX LEAKS

My experience in other situations where a shaft seal leaks is that there is sometimes a problem with the bearing such that the shaft isn't running true and the seal gets stretched causing the leak.

I agree with checking the bearings - in addition the "true" running of the shaft itself, should be checked, along with any damage to the shaft surface, which may be impacting on the seal.

Your problem screams that the vent line off the oil tank is plugged or too small. It should be 3/8" all the way to the end.

Make sure there are no dirt dauber or other insect nests in the line as well.

Excess crankcase pressure will cause this problem.

Glenn Mathis wrote:

Your problem screams that the vent line off the oil tank is plugged or too small. It should be 3/8" all the way to the end.

Make sure there are no dirt dauber or other insect nests in the line as well.

Excess crankcase pressure will cause this problem.

And a plugged oil tank vent line may result in oil starvation ...