USCG Exam PracticeDiesel engine principles (motor propulsion)
The thermostatic valve in a marine diesel indirect cooling system serves which primary function?
- A. It regulates seawater flow through the sea suction strainer to prevent cavitation
- ✓ It bypasses the jacket-water cooler until the engine reaches operating temperature, then progressively admits jacket water to the coolerCorrect
- C. It controls the chemical treatment dosing rate to the jacket-water expansion tank
- D. It diverts raw seawater away from the lube-oil cooler when jacket-water temperature is low
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