I've got an oil leak on our Aztec left engine, IO540 C4B5. The hydraulic
pump on the left engine has a drain/vent hose that is leaking engine oil. It
is definitely not hyd oil. I had a new garlock oil seal pressed into the
accessory drive adapter housing thinking that this was how the oil was
passing into the hyd pump housing, the old seal was hard as a rock. Tonight
I test flew it for about 20 minutes, operating the flaps and gear as normal.
After landing there were a few oil streaks along the inner main gear door.
After refueling and parking the airplane, there were more streaks and a few
drops dripped from the drain hose.

I popped the inner cowl off and pulled the hyd pump housing drain hose, sure
enough, that's where it was coming from.

Does the garlock seal require some time to absorb oil and expand against the
accessory drive shaft? I've been told both yes and no. I'm hoping that after
a flight or two that the seal will lap itself against the shaft.

Any opinions?

Thanks,
Jim