BMW E46 – How To Flush Your Coolant

Have your car on Jack stands to make it easier to get the screw driver underneath the car to open the splash shield screws.
(This is an optional step, as some may be able to do it without Jack stands)

Use the flat head screwdriver for removing the front Expanding Rivets and the Philips head screwdriver for the Quick-release ones.

Remove cap and then get underneath the engine car where the splash shield was removed and locate the big blue drain plug, remove it with a flat head screw driver.

Let the water drain. You can loosen the small blue plug for faster drainage. Use the pan to keep the drain, it’s poisonous so make sure to clean any left overs on the floor.

Should be a 13mm standard socket or 8mm hex socket (depending on your engine and year). Replace the washer and and let all the water drain.

This is to enable all the water to come out. Turn the black bleed, screw it with a flat head screw driver. Then Using a 50% distilled water 50% engine coolant mix, slowly fill the expansion tank until the coolant comes out of the expansion tank bleeder screw.

Working at top of the radiator, loosen the coolant expansion tank bleeder screw, then turn the ignition ON but do not start engine.

Now set the temperature controls in vehicle interior to full warm and the blower fan speed on low.

Then fill the expansion tank slowly until the coolant is coming out of the expansion tank bleeder screw and make sure it’s bubbles free. Then tighten the expansion tank bleeder screw.

Start and run your engine at idle until it reaches operating temperature.

Shut engine off and allow it to cool. Then after enough time, re-install the engine splash shield and check the cooling system for leaks. And you’re done!