Description Salt and brackish water is a corrosive killer of the aluminum from which outboards are made, so flushing every time after saltwater use is a must. Left unchecked inside the cooling passages, saltwater will quickly build up and may cause cooling blockages, leading to overheating and, over time, can corrode an engine from inside out. All outboard manufacturers recommend flushing after every use in salt, brackish, dirty, or polluted waters. Operating an engine in sandy, silty, or muddy fresh water also dictates the need for periodic flushing.
