Lube change in 1976 Mercury 850?

[Scott Rickard]

I think I'm going crazy. The lower screw for draining and filling is right where I'd expect it to be, but I don't see a corresponding upper one. This can't be. It must have a vent screw, right?

Any old Merc owners here willing to shed some light?

[fishkisser]

If I remember right , the upper plug is labeled vent because the units are filled from bottom to top, to prevent air lock. the drain is the same type of screw on the bottom front of the bullet same side of the unit.
But its been a long time ... Barney ...

[namu mac]

Me too-if I remember right. The screw is a small stainless and not like the drain screw. Maybe I think

[Scott Rickard]

Thanks guys - I think that's what was throwing me off. The vent screw probably doesn't look like the drain screw. I'll report back...