Can anyone tell me what this is..

[Rconautique]

Got home from a day on the lake and found a lot of v-drive fluid in the bilge and level very low. I have the PCM Power Plus Vdrive 1.48:1 in a 2007 210. The oil appears to be leaking from this little stem sticking up on the top of the vdrive unit, near where it mates to the transmission. When I press on the black plastic cap it goes down a half inch then pops back up like a spring is under there. The cap spins freely but does not unscrew and I can't pull it straight off either. Anybody know what this stem/port is? I see it on PCM's parts diagram but it is not labeled.

[nukemustang]

Vent? http://www.planetnautique.com/vb3/sh...ique-210/page3

[Rconautique]

Looks exactly right, thanks nukemustang. Now I have to
figure out how the heck oil is making it out the vent.