Yea, sorr, 1988 mercury 3.0 with mercruiser alpha 1, I presume.
upon further inspection, it is a sound from the exhaust bellows, which is split.
The hose im squeezing is a radiator type( 2.5 inch or so) hose, on the very top, looks like it goes into a housing, then exits with a 1 inch going around to the back
Boats drawing in a heck of a lot of water.
so I'm checking everything I know how to.
My most trusted repair shop is 3 weeks out just for diagnosis