Why is the coolant level low?
2 Answers
There are several reasons for coolant loss, including natural consumption, coolant leakage, or coolant entering the combustion chamber to participate in combustion, such as cylinder block cracks, cylinder head gasket burning or corrosion deformation, etc. Natural consumption: Various fluids in a car inevitably experience consumption. Since coolant is responsible for cooling the car engine and is often in a high-temperature state, it is normal for coolant to lose about 10%-36% in a year under normal circumstances. Coolant leakage: If the coolant needs frequent replenishment, it indicates there is a leakage. Rubber-metal pipes and fittings, often exposed to high temperatures, may age due to thermal expansion and contraction, leading to tiny gaps through which coolant can seep. Common leakage-prone areas include the radiator hoses, air conditioning heater hoses, thermostat, and water pump seals. Regularly inspecting sealing glue, tightening clamps, and timely maintenance can ensure driving safety and prevent breakdowns or accidents. Coolant entering the combustion chamber to participate in combustion, such as cylinder block cracks, cylinder head gasket burning or corrosion deformation, etc.: In this case, you can check the oil dipstick to see if the engine oil has emulsified (oil emulsification means the oil turns into a milky liquid, appearing milky white or milky yellow, resembling stirred flour paste with bubbles). This happens because the cylinder block has oil and water passages. Once the cylinder head gasket is damaged, the water passage cannot be sealed, allowing coolant to flow into the oil passage. The solution is to replace the cylinder head gasket.
I've been driving for several years and have noticed that there are several common reasons for low coolant levels. Leakage is the primary issue—small cracks in an aging radiator, loose hose connections, or worn water pump seals can all cause slow seepage, especially in winter when rubber contracts and leaks more easily. Prolonged high-temperature driving can also accelerate evaporation, but normal consumption is minimal. If the engine cylinder head gasket is damaged, coolant can mix with the engine oil, turning it milky white, which can severely damage the engine. I've seen a friend neglect this issue, leading to cylinder scoring and a major overhaul. Regularly check the expansion tank level when the engine is cool, keeping it at the proper level, and use OEM coolant for periodic replacements to prevent most problems. Don’t forget to inspect the cap’s seal—insufficient pressure can also accelerate loss. Routine maintenance is a wise investment.
