🔍 Key Concepts

• Closed freshwater cooling system operation on a diesel engine • How heat exchangers remove heat from engine coolant • Typical symptoms of mechanical failure vs. gradual performance loss

💭 Think About

• Ask yourself which problem would most likely cause a slow, gradual rise in coolant temperature rather than an immediate overheat. • Think about what happens inside a heat exchanger when scale, marine growth, or dirt builds up on the tubes. • Consider whether a broken pump shaft would allow the engine to keep running for very long without a rapid overheat.

✅ Before You Answer

• Verify which fault would reduce heat-transfer efficiency while still allowing coolant to circulate. • Check which fault would likely cause sudden, severe overheating instead of a gradual temperature increase. • Confirm which option would most directly affect the cooling surface area or cleanliness of the heat exchanger.