Mercury Inboard taking on water and splashing on engine

[sing4kristen]

Hi folks. I inherited a mercury Inboard motor boat that I love. It is very old but in great shape. I took it out the other day and for the first time the bilge pump came on and it was pumping out some pretty significant amounts of water. When I opened the engine compartment it looks like it was spraying on the engine as well. It seemed to be coming from the right side of the motor as you look down at it. It has a tube or hole or whatever in the rear with a screen on it. I don't know what that is for and couldn't find it in the owners manual. When I got back home I checked the plug bolt and it was tight. No hoses seemed to be a problem but the cap over that hole or tube with the screen on it wasn't screwed on all the way. I don't see how this would make a difference as it is just a screen but don't know what would stop water from coming in since the cover is just a screen. Forgive me, I am a novice boat owner but want to do right by my dad who gave it to me and is currently in the hospital dying. It looks like the water is coming from the area where that tube is located but there is a wall there that I can't see behind to know. What is that tube with the screen? What is it's function? And how/why could it suddenly be leaking so significantly? Thanks in advance.

 

[Bt Doctur]

Not knowing what your working on make an answer vert difficult

 

[Faztbullet]

Picture? Sounds like a heat exchanger

 

[poconojoe]

Give more details and/or post up some pictures.
A serial number off the engine is the best identification means.

Boats are not like cars. The year and engine size mean almost nothing. The boat itself usually means nothing. There were too many different engines and brand engines used. Even many variations of the same size engines.
There's closed cooling and raw water cooling.

There's inboard, outboard and I/O (inboard/outboard).