What is THIS????

[Aquamaniac]

Figured maybe someone here with ancient Merc experience might help on this issue....
Noted bubbles and spray shooting up from the access hole (for torque plate) in lower unit of my old 150.
The plug for the hole has been missing since I have had the motor, but I had not noticed anything like this before.
Here is a pic:



What could explain this? Leak in the bottom seal of exhaust tuner? Problem with tuner itself?
Motor seems to run fine.
Is this something that needs fixing or just plug the hole and ignore?
Hope someone out there has some advice.....this old motor is starting to wear on me

[Blue Agave]

The purpose for that hole is to access the bolt that holds the zinc directly under the hole. 

[Aquamaniac]

Correct...it is access for torque plate as noted.
What I am concerned with is whether the exhaust escaping through this hole is abnormal (indicating an exhaust tube seal failure, or ???) or simply normal and would not be noticed if hole was plugged. From what I gather studying parts diagrams and Service Manual....fixing the seals (upper or lower) would be major job. Ugh.

[GoneFission]

OK - no big deal here.  Just replace the torque tab and the bubbles will go away.  Kinda weird how this works, but it's not a big deal to run without it, just better if the tab and bolt are in place.