Learning the HARD way...
Join Date: Jan 2007
Location: Boston / Ft Myers Area
Thanked 191 Times in 187 Posts
Rep Power: 11
I suspect that something is blocking the raw water intake. Maybe not completely, but something is in there.
Close the seacock, then open your raw water strainer. Clean out any junk. Leaving the strainer open, open the seacock. does water flow out as you would expect, or is there less than you would have thought?. If less, then the problem is the line to the strainer, the seacock, or the through hull (you don't have a strainer on the outside of the through hull - do you?). If water flows well, clean up the spill, then check the line from the strainer to the pump, and the pump itself.
Because you seem to say that at one point water flow stopped completely, I do not suspect your heat exchanger.