Recently bought a 2000 Sport Craft with a 5.7L Carb MIE SN Ol392532 and it has fresh water cooling on it. It has run in salt water for 600 hours and never had the manifolds changed. In my last I/O the parts guy said to change the manifolds every 4 years because it was raw water cooled. I know salt water is still pulled in to cool the fresh water but does salt water or fresh water run through the manifolds. There is a rust color that stays on the stern of the boat where the exhaust comes out and the left side only has half the amount of water coming out the exhaust than the right when I hook up the hose to flush with fresh water (an addition the original owner put in). I'm guessing the manifolds have salt water running through them and they are way overdue. Can I get an expert opinion? Thanks, JEC
