2. Automobile cooling system is generally composed of cooling water tank, cooling fan, water pump, thermostat, water pipe and other parts, which is an indispensable part of the normal operation of the engine. So, why does the automobile cooling system need to be vented? This is because the automobile cooling system is a closed circulation system. When there is air inside, it will hinder the normal circulation of coolant, reduce the cooling effect, and lead to excessive engine temperature. Just like the pressure cooker we cook, so does the cooling system. If the high-pressure steam inside is not exhausted at last, it will cause the failure of water pipe bursting.