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MerCruiser Cooling System

MerCruiser Cooling System

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Cooling System

The Mercruiser cooling system works by circulating cold water around the engine block to cool your MerCruiser engine parts. There are two types of cooling systems; raw water cooling and closed cooling systems. The MerCruiser raw water cooling system functions by drawing water from the lake or sea and carrying it through the engine block to the exhaust system. A closed cooling system employs a heat exchanger, which uses raw seawater to cool hot distilled water. The cooled distilled water runs through the engine block and cools the engine instead of the raw seawater.

The closed cooling system is kinder to the water distribution system than the the raw water cooling system because it is less prone to rusting. A raw water cooling system has a shorter lifespan than a closed cooling system. A fresh water cooling system Mercruiser allows your engine to run at higher temperatures, resulting in a better functioning fuel system.

7.4 Mercruiser cooling system

The thermostat is a small but essential cooling system component that is often overlooked. The thermostat valve regulates the engine's temperature by closing or opening its valve. The valve closes to increase engine temperature by preventing cooling water from passing through the engine block. Once the temperature is high enough, the valve opens to allow cooling water to pass around the heat exchanger and circulating pump to cool the engine. You can refer to the 7.4 Mercruiser cooling system diagram to better understand how the entire system works.

NuWave Marine recommends regular inspection of your cooling system, from the seawater strainer, raw water pump, heat exchanger hoes, and thermostat housing to the circulating water pump. A faulty thermostat will either fail to open or close. If the thermostat valve remains closed, the engine will overheat and cause damage to the ignition system. We recommend replacing the thermostat every two years and installing an electric overheat horn to prevent overheating damages.

Cooling System Replacement Parts You Can Depend On

NuWave Marine has provided boat owners and marine mechanics with quality OEM and aftermarket replacement parts for four decades. We believe in investing in premium replacement parts like exhaust manifold kits, serpentine belts, and circulating pumps for peak marine engine performance. 

Contact us today and our experienced team of marine mechanics will help you find the right replacement parts for your boat's engine.