The invention relates to a method and a device for cooling an internal combustion engine. An aqueous, non-ionic coolant composition is used in a cooling circuit (14) of the internal combustion engine (11). In order to also ensure long-lasting protection against corrosion for light metal components of the engine that come into contact with the coolant, e.g. components made of magnesium or magnesium alloys, the cooling circuit has at least one deionization device (28), for example, an ion exchanger, for the coolant.