As a preventative measure, E46 owners should attempt to replace certain parts on their cars on a regular basis. The typical service interval that is suggested a cooling overhaul falls in the every 75,000-90,000-range. If you have the ability to spend money on parts, you can save money on labor by doing this work yourself. On this article, I will be addressing the replacement of major components on the cooling system on the BMW E46. This guide should apply to most E46 vehicles: the 323i, 325i, 328i, and 330i models.