[Russf]

I understand but the impeller would need to be removed as it will block the flow of cleaning agent. 

Tom. As i understand it the impeller is what circulates the fluid. You use the raw water system with the raw water intake valve closed to suck in the BB solution until it runs out the exhaust at which point you turn the engine off and then let the solution sit in the system while it does its work for about six hours. Then with the raw water intake valve opened you start the engine and then the incoming raw water pushes out the BB solution with the material that it has dissolved.