Turn the expansion tank cap slightly to the left and release the pressure in the cooling system. Then unscrew the cap and remove it.
Warning: Do not open the cap when the engine is hot - it is dangerous! The cooling system is under pressure. Remove the cap only when the coolant temperature is below 60C. Cover the cap with a thick cloth before unscrewing.
Raise and support the vehicle from the front, remove the lower casing (mudguard) of the engine compartment.
Place a clean drain pan under the radiator and unscrew the drain plug at the bottom of the radiator. Use a large screwdriver or even a coin to turn the plug.
Place the drain pan under the engine and remove the drain plug on the cylinder block. The plug is located under the exhaust manifold.
Allow the coolant to drain completely.
Screw the drain plug with a new sealing ring into the cylinder block and tighten to a torque of 40 Nm.
Loosen the radiator drain plug using a large screwdriver or coin.
(Original publication posted on the website «BMWman.ru»)