Is that ok to hammer on this part of the engine? It wont crack anything or screw it up?
I had to use on of those tools before, just not on a boat motor. Is heating it up with a torch out of the question?
You don't have to beat the snot out of hose tools. The motor can take it. Heat is not out of the question, as a last resort. But if the plug is brass, heat may be counter-productive. Brass expands faster when heated than aluminum does. In other words. it will get tighter when heated.