Mercruiser 3.0L Leaking water

[newbie_owner]

Update,

I took the boat out today and had someone drive while I watched the engine. I have found the leak, at like 4000 RMP water dropplets begine to appear and drip down the block. Looks like a crack in the cylinder head just below the spark plug. Here are some pictures.

http://i1368.photobucket.com/albums/ag195/2006_175/cyl2_zpsbeca61aa.jpg

At a closer look you can see a hair line crack:

http://i1368.photobucket.com/albums/ag195/2006_175/Cyl_zps94fb48cc.jpg

So any idea what it costs to replace a cylinder head?

 

[newbie_owner]

Spoke to the mechanic today and he said if it is just a water jacket external leak he could JB weld the crack. He said he would remove the head, inspect, test, repair, new head gasket, re-install for around $700. I just found a re-manufactured head for $489 so I bought it: http://www.michiganmotorz.com/cylinder-head-1991current-remanufactured-p-3789.html . I would rather have it done right. Dropping it off next week.

I have a feeling that it was sold to me that way. I have only had the boat for 2 years and it seems like a short time for all that rust and corrosion. I will let you know the total bill once I pick it up.

Thanks again for everyone's help.