muriatic acid flush

[76GMC1500]

If you flush, I would think it should be done with a caustic solution and not an acid. *Acids will remove rust and leave behind bare iron which will just rust up again. *Corrosion that occurs when bases are involved usually involve the formation of magnatite and hematite which will actually protect the iron from further corrosion. *Black oxides are good, red or pitting oxides are bad. *We run the water in high pressure boilers at a pH around 10 or 11 in order to encourage the formation of black oxides on the boiler tubes.

Since this is an outboard with an aluminum block, I would just flush with fresh water and not worry. Aluminum does just fine and forming its own oxide barrier to stop corrosion.