🔍 Key Concepts

• Closed freshwater cooling system operation in diesel engines • How a radiator controls engine coolant temperature • Purpose and function of radiator louvers or shutters on marine engines

💭 Think About

• Which option actually controls how much heat is rejected from the coolant to the air, rather than adding more heat to the system? • On engines with radiators or heat exchangers, what adjustable device is often used to regulate coolant temperature in varying ambient conditions? • Think about which choice changes the cooling system’s efficiency without modifying the engine load or adding extra heat sources.

✅ Before You Answer

• Confirm which components are designed specifically to regulate airflow through the radiator core. • Eliminate any options that would increase heat in the cooling system instead of removing it. • Identify the device that can be manually or automatically adjusted to maintain the desired coolant temperature under different operating conditions.