Cooling sys leak; 2006 Elite V C4; 350 Mercruiser

[bredman 0]

New to the forum.... like 10 minutes new.  Thanks for having me.  

Recently purchased a 2006 Elite V C4, Air Warrior. During the first couple of outings, I noticed that we were getting an inordinate amount of water in the bilge and the bilge pump was having to work overtime. After today's outing, inspected further and noticed the leak show in the component in the attached pic.  It is on the starboard side, rear of the motor.  I believe it is a component of the cooling system particularly the manifold maybe.  It is down, very low in the transom area and has a blue drain plug.  The leak doesn't appear to be from a hose, but the very bottom of this "knuckle" looking component. I have a 20 sec video that shows the leak, but unable to upload it here due to size restrictions. I'd sure appreciate any help identifying what I've discovered and any advice on handling the leak.  The pic is from directly above the "knuckle" and for what it is worth, this component appears to be plastic and has a rubber cap at the top.  

Thanks in advance for any help members might provide!