i have noticed a salt water stain and some water on the under side of my engine cover, i have pinpointed the leak and it seems to be coming out the 3" plug on top of my heat exchanger, engine is running at 180 190 degre when underway at 3000 rpms, does this cap usually come off or is it a nightmare? it seems to have a 5/8 or 1/2 hex head for removal but im not touching it until i get some input from someone who has attempted it already, also do i drain the coolant before removing it?
