Raw water cooled vs fresh water cooled

"Hi. We boat on Lake Michigan

"Hi. We boat on Lake Michigan and plan on doing the great loop this May, the engines are currently raw water cooled. The boat will be in salt water for about 6 months and then back to fresh water. Should I install heat exchangers for the trip, or a flushing system or since I'm only in salt water for a short period of time, just flush them out now and then with fresh water. Any and all advice is appricated especially if you are currently in salt water. Thank you and Happy Easter, Jeff"

"If you install a heat exchang

"If you install a heat exchanger system you would want to continue to use it in the lake. There is considerable expensense and installation work involved in putting a heat exchanger system on but it is a superior system in all enviorments. With an enclosed system, besides avoiding corrosive water running through your engine, you can also run it at a higher temperature (195 degrees) and use coolant/antifreeze. Raw water systems must run cooler, 160 degrees in fresh water rivers and lakes and no higher than 145 degrees in ocean water.

I you do not get around to getting the enclosed system, then be sure to flush the engine with a garden hose and adapter after every run and use a 145 degree thermostat when in ocean water."