Volvo Saildrive Oil Leak

[Sid at SailAway]

I have a Lagoon 410 with the Volvo saildrives. I have noticed an oil leak on the port drive. The leak is coming from the top of the drive. The only thing on top of the drive is the filler and a square plate of some sort. The drive only has around 700 hrs on it. When I take off the filler cap i hear a hissing, but cannot determine if it's from vacuum or pressure in the drive. Neither makes much sense. Could the drive be pressurizing and forcing the oil out the top? Does the drive have a vent of some sort? Why would the drive pressurize? The oil is clean in the drive, as in no water. The stdb side is fine and this has me scratching my head...Any thoughts would be appreciated....

[Cotemar]

The hissing you hear is pressure. Happens everytime I open mine.
You may have to much oil in the sail drive.
You may have seawater leaking in throught the 2 lower seals if the oil is milky white

There is a lot of good Volvo Sail Drive info here.

http://www.cruisersforum.com/forums/...tml#post599691