I have been reading many of the threads on this subject but I'm still a little confused. If I am running on 1 engine due to breakdown, which lines must be closed off. I know the inlet line running from my jet pump to my tuned pipe has to be blocked, but what about the line running from my exhaust manifold to the "tail pipe"? Is it possible for water to back flow through that into the engine, or even the water outlet for that matter?