Those are the exhaust relief holes. They make it easier for the engine to
idle. The back pressure from the thru prop while sittting in the water is a
bit high.

wrote in message
ups.com...
I have a 2002 model Mercruiser 4.3 EFI with an Alpha 1 outdrive. Where
does the exhaust come out? I took the boat out of the water today and
ran it on the flush muffs. I expected the exhaust and cooling water to
come out of the propeller, but quite a bit of water and exhaust fumes
came out of the leg where it joins the back of the boat. Is this
normal?

Thanks for any comments.