When must a thermostat be fully open?

When must a thermostat be fully open?

• A. About 11.1°C below the start to open temperature
• B. About 11.1°C above the start to open temperature
• C. About 25°C above the start to open temperature
• D. About 5°C above the start to open temperature

Answer: (B)

The main idea is that a thermostat doesn’t snap fully open at the moment it starts to open. It begins to open at a defined start-to-open temperature, and it continues to open until it’s fully open when the coolant is about 11.1°C hotter than that starting point. In practice, this means the thermostat reaches full opening roughly 11°C (about 20°F) above the start-to-open temperature. So the correct statement is that it becomes fully open about 11.1°C above the start-to-open temperature. This gradual rise helps regulate engine temperature smoothly.

The main idea is that a thermostat doesn’t snap fully open at the moment it starts to open. It begins to open at a defined start-to-open temperature, and it continues to open until it’s fully open when the coolant is about 11.1°C hotter than that starting point. In practice, this means the thermostat reaches full opening roughly 11°C (about 20°F) above the start-to-open temperature. So the correct statement is that it becomes fully open about 11.1°C above the start-to-open temperature. This gradual rise helps regulate engine temperature smoothly.