USCG Exam PracticeDiesel engine principles (motor propulsion)
In a marine diesel's indirect cooling system, what is the primary purpose of the thermostatic (temperature-regulating) valve?
- A. To regulate seawater flow through the sea suction strainer
- ✓ To bypass the jacket-water cooler until the engine reaches operating temperature, then admit jacket water to the coolerCorrect
- C. To control the flow of treated fresh water into the expansion tank
- D. To limit the maximum pressure in the jacket-water circuit
Why B is correct
The thermostatic valve bypasses the cooler while the engine is cold, then progressively admits jacket water to the cooler as the engine heats up, holding outlet temperature in a narrow band regardless of load or sea temperature. (NAVEDTRA 14075 §3-5)
Cited:NAVEDTRA 14075 §3-5