Jacket cooling water

Jacket cooling water is the treated fresh water circulated through the cooling passages around a marine engine’s cylinder liners, jackets, and heads to carry away combustion heat. It is part of the high-temperature circuit, leaving the engine at about 85 to 90 degrees C, and is dosed with corrosion inhibitor and nitrite to protect the iron and aluminum surfaces and to control cavitation erosion on the wet liner. The circuit runs closed through a central cooler against the low-temperature loop, with an expansion tank for venting and make-up, and often supplies the fresh-water generator with its waste heat.