How do you get rust out of a inboard boat engine?

Answer 1

If you have rusty colored water in cooling passages this is normal as the inside of the engine blocks are not treated. This will usually flush out when running unless block has set a extend period(several years). If used in salt or brackish water you need to start and flush motor on a hose with muff and use a neutralizer like salt away..

Answer 2

by adding some vinegar or citric acid