What is the reason for the decrease in newly replaced coolant the next day?
2 Answers
Coolant reduction is a normal phenomenon, including engine oil, windshield washer fluid, etc., which will decrease during the use of the car. The main reason for the decrease in coolant is natural evaporation. Coolant has a cooling effect on the car engine, which often operates at high temperatures. Since the coolant is in contact with the engine, some consumption is normal. Methods for selecting coolant: The basic indicators of coolant are the freezing point and boiling point. On the market, coolant is available in several specifications with freezing points of -15℃, -25℃, -30℃, -40℃, etc. Generally, it is advisable to choose a coolant with a freezing point at least 10℃ lower than the lowest temperature in your region. Methods to determine if coolant is insufficient: Observe the coolant warning light on the dashboard. If it lights up, it is likely due to insufficient coolant, although it could also be caused by excessively high cylinder temperature. Check the coolant reservoir. If the level is below the minimum mark (MIN), do not continue driving and add coolant promptly. Check the water level scale on the coolant tank. The normal coolant level should be between the maximum and minimum marks. To determine if coolant is insufficient, check the scale. If the coolant is below the minimum mark, it indicates a shortage of coolant.
The coolant level dropped the day after a refill, which I find quite common. As someone experienced with cars, the most frequent cause is air bubbles remaining in the system. When replacing coolant, air needs to be bled out, and during this process, bubbles may rise, naturally lowering the fluid level—it usually stabilizes after a few days. Additionally, overfilling can lead to spillage since the engine expands when heated, causing excess fluid to leak out. However, if the level drops rapidly or significantly, potential leaks must be checked, such as loose hose connections, aging radiator seals, or cracks in the radiator. I once ignored this and ended up with an overheating alarm, later paying for engine repairs. My advice: monitor it for a few days; if the level drops abnormally, check for fluid drips under the parking spot and consult a professional promptly. Insufficient coolant impairs engine cooling, risking component damage—safety shouldn’t wait.
