Do Cars Need to Be Filled with Water?
2 Answers
Ordinary household cars cannot be filled with water. The engine of a car is water-cooled, but it requires specialized coolant; water cannot be used as the engine's coolant. Using water as a coolant can lead to scale buildup in the engine's water passages. Additionally, water has a relatively low boiling point and a high freezing point, making it unsuitable as a coolant. In a water-cooled engine, the coolant continuously circulates within the engine during operation to dissipate heat, thereby removing excess heat from the engine. The coolant follows two circulation paths within the engine: a major cycle and a minor cycle. When the engine starts, the coolant undergoes the minor cycle, during which it does not pass through the radiator, aiding in the engine's warm-up. After the engine has been running for a while, the coolant switches to the major cycle, passing through the radiator to dissipate heat, thus maintaining the engine within a reasonable operating temperature range. The coolant needs to be replaced periodically. If not replaced for a long time, the coolant's boiling point may decrease and its freezing point may rise, which can affect the engine's normal operation.
As a seasoned driver who has owned seven or eight cars over the years, I can share some insights about "adding water" to vehicles. Cars do require "water," but not tap water or mineral water—it's specifically formulated fluids. During summer driving, dirty windshields are a common issue, so you'll need to fill the reservoir under the windshield with washer fluid. If you're too lazy to buy the dedicated solution, temporarily using tap water is acceptable, but in winter, you must switch to anti-freeze washer fluid. The small tank next to the engine is part of the cooling system, which requires coolant—this fluid prevents freezing in winter and boiling in summer, making it far more reliable than plain water. In emergencies, if coolant leaks completely, you can temporarily top it off with purified water, but you must replace it with fresh coolant as soon as possible. As for older car batteries, they used to require distilled water, but modern vehicles generally don’t need such maintenance anymore.
