How to Do a Rad Flush on a BMW E36

1. Jack up the BMW with a floor jack and lower it onto a jack stand. Repeat for the remaining corners of the car so all four corners are supported. Let the car cool down fully if it was recently driven.
2. Turn the heater controls to the hottest setting. Turn the ignition key to the 'On' position. Turn on the fan and leave it on the slowest setting. These steps will open the heater valves.
3. Locate the engine block coolant drain plug, which is located on the block, just under the manifold on the passenger's side of the engine.
4. Place a coolant catch container directly below the drain bolt. Remove the drain plug with a socket and ratchet and allow the coolant to drain into the container. If you remove the plug from below the car, wear eye protection.
5. Allow all of the coolant to drain out. Reinstall the bolt with a new aluminum washer. Tighten the bolt to 18 foot-pounds.
6. Move the coolant container under the radiator. Slowly remove the plastic drain plug located in the bottom of the radiator. Replace the drain plug once all of the coolant has drained out. Tighten the plug to 18 to 27 inch-pounds. Do not over tighten the plug.
7. Remove the small bleed located just to the right of the radiator cap. On M3s, the screw is on the thermostat housing.
8. Place a funnel in the expansion tank opening. Fill the tank with a 50/50 mix of coolant and distilled water. Fill the coolant system slowly to allow the coolant to reach all of the areas of the system. A 4-cylinder engines use seven quarts of fluid, and 6-cylinders use 10.6 qts. of fluid. The M3's engine uses 11.1 qts. of fluid
9. Bleed the cooling system only if the coolant expansion tank is attached to the side of the radiator. If the expansion tank is separate, the system will bleed itself.
10. Ensure that the bleed screw has been removed. Fill the expansion tank until fluid starts to pour out of the bleeder valve. Fill the tank until there are no bubbles in the coolant coming out of the valve. Tighten the bleed screw to 71 inch-pounds.
11. Start the engine and let it warm up to operating temperature. Turn off the motor and let it cool. Top up the expansion tank with coolant if necessary. Lower the car off of the jack stands.