USCG Exam PracticeDiesel engine principles (motor propulsion)
In a marine indirect (closed jacket-water) cooling system, what is the function of the thermostatic valve?
- A. It regulates the flow of treated fresh water into the seawater strainer to prevent fouling
- ✓ It bypasses the cooler until jacket water reaches operating temperature, then admits it to the cooler to hold outlet temperature in a narrow bandCorrect
- C. It opens the seawater suction directly to the cylinder jackets when the engine overheats
- D. It controls the chemical treatment dosing rate based on jacket-water temperature
Why B is correct
NAVEDTRA 14075 §3-5 describes the thermostatic valve as bypassing the cooler until the jacket water is warm, then admitting it to the cooler as the engine heats up, holding outlet temperature in a narrow band regardless of load or sea temperature.
Cited:NAVEDTRA 14075 §3-5