After pulling the exhaust manifold today. I found the brass core plug on the head popped out a little. It was the plug furthest aft. I drove it back in with a block of wood and hammer. Now I'm having second thougths on putting the manifold back on as it will block the plug. Do these plugs usually leak after reseating? Maybe it should just be replaced. A little more info on the engine. It was winterized in September. Block drained and then filled up with antifreeze through t-stat housing.It was running good at the time. No water in oil then or now. Manifold is being changed for maintenance. Engine was pulled from my brothers boat and placed in mine. It ran good for him last summer till the engine coupler melted down. Not sure how or why the plug was pushed out. What do you guys think here? Troubles?
