Since your engine produces so much heat that has to be expelled anyway, the engineers decided to send it through a BMW heater core to warm the passenger compartment instead of using an electric or gas-fired heater. But as your car ages, the heater core suffers from the same problems that your vehicle's radiator suffers from: corrosion and leaks. If you've changed your antifreeze religiously every two years or so, you may not have any crud built up in your heater core. Once your BMW heater core begins to leak, interior damage, foul odors, mold, and rust are close behind.But leaks in the heater core mean you end up with antifreeze and water on the inside of your car. Order BMW heater cores now through our catalog of parts here on our website.