Need some expert advice. I made a engine flush kit by drilling out a spare strainer cap to allow for a garden hose to be connected. I plan on closing the sea cock valve, removing the strainer cap and put the modified cap on, connect a garden hose to the cap and put the other end in a bucket of pink stuff, start the engine and wait for pink to flow out the exhaust. My question is since the sea cock is closed when I start the engine where will the water that is being sucked up by the impellers go, the boat is in the water. Will it build up too much pressure or damage the impellers? Any advice would be appreciated. Thank you. 7.4l 454ci bluewaters. 1994 350 express bridge.