So I'm not very mechanical, and my dad, who is, helped me replace the
water pump (all of it) in my 1985 mercruiser alpha one stern drive.

Since we didn't know what the hell we were doing, and didn't really
follow the instructions in my SELOC manual, we ended up installing the
water pump without one part (which we suspected was missing but
thought maybe since it didn't come with this particular part that
maybe we didn't need it).. Before installing the water pump, we
poured the gear lube oil back into cavity below the water pump (this
took freakin' forever).... then installed the water pump, and
reattached the lower unit.

I didn't actually run the engine at this point because I suspected
missing parts, but one thing I noticed was gear lube oil leaking out
the weephole in the lower unit.

Well, today, we removed the lower unit again and completed the water
pump installation. The two pieces we hadn't installed were the
flinger (aka "rubber ring") that sits on top of the water pump
housing, and the drive shaft o-ring. So we added those parts, and
noted the oil leak on the shift shaft. Not sure where the oil came
from. We also replaced the rubber washer in the oil passageway
between the upper and lower unit.

At this poitn, btw, the lower unit was still full of oil. We'd never
completely refilled the oil but since we were only installing a few
things above the water pump we just left the oil in there.

After reattaching the lower unit again, I proceeded to fill the unit
with gear lube. Removed the vent and drain screws, and shoved in a
squeezable bottle of marine gear lube I'd picked up at an auto parts
shop. And I squeezed. I don't know how much had come out of the 10oz
squeeze tube, but suddenly, oil started pouring out the weephole!

Now, I haven't removed the lower unit again to inspect, but I wondered
what I ought to do. Clearly I've got a leak somewhere, I'm just not
sure where to look. Perhaps the oil seal on the shift shaft is bad.
Wouldn't surprise me, I ran the boat for 5 minutes with a completely
failed water impeller (unknowningly). I wasn't paying attention to
the temp gauge, and we heated the einge so hot that even after 45
minutes of sitting in the water waiting, it was almost too hot to
touch!

Recommendations, besides paying better attention to the temp gauge in
the future?

Thanks.

Rick