What Is Main Engine Cooling System?

Heat Exchangers and Maritime Cooling Systems

Both marine and automotive engines are cooled by circulating water through the engine block. Marine engines are unique in that they have two distinct cooling systems. The conventional raw water system and the fresh water cooling system.

Devices for Cooling Raw Water
Raw water cooling systems draw water from the environment (seawater or lake water). Water is pumped from the source to the engine block, where it is forced through the engine block by the engine circulation pump and ejected through the exhaust. Raw water cooling systems are quite basic and are used on the majority of marine engines. In most situations, the raw water pump is housed within the outdrive. The raw water pump on larger engines and inboard engines is positioned within the boat and is powered by a v-belt or directly off the crankshaft. There are hidden dangers that can accrue over time and cost you a lot of money in repairs. Using salt water as a coolant in your engine is dangerous. Salt water is extremely corrosive. Putting salt water through your engine block and exhaust manifolds will cause damaging corrosion that will go unnoticed until the engine or exhaust manifolds break.

In general, marine engines cooled with raw water, particularly those cooled with salt water, have a lower life duration than marine engines cooled using a closed cooling system.

Fresh Water Heat Exchanger Systems and Keel Cooled Systems
Fresh water cooling systems, also known as closed cooling systems, come in a variety of configurations. The most popular form employs a Heat Exchanger, which acts similarly to your car's radiator. Coolant (antifreeze) circulates through one side of the heat exchanger and is cooled by raw water that circulates through the other side. The engine coolant is then returned to the engine. The raw water is ejected from the boat via the exhaust. A Keel Cooler is another frequent type of closed cooling system. This is accomplished by omitting the usage of a heat exchanger. Instead of pouring raw water into the vessel's heat exchanger, where it cools the coolant, the coolant is routed through pipes or aluminum extrusions on the exterior of the hull, where it cools before being put back into the engine. Keel coolers eliminate the requirement for a heat exchanger, raw water pump, and other components required for pumping raw water into the heat exchanger.