Cars Comp

How to Drain the Coolant in a 2002 BMW 325i E46

Draining the System
1. Park the vehicle and allow it to cool or wait long enough so that you can place your hand on the radiator for 10 seconds without discomfort. Remove the cap from the coolant overflow tank, then loosen the vent plug on the tank.
2. Unbolt the underbody paneling under the radiator to access the drain plug on the radiator and engine. Place a catch pan under the radiator, then turn the drain plug at the bottom of the radiator counterclockwise. Be ready for a rush of possibly warm fluid, and dont get any in your eyes. Wait for the coolant flow to stop, then pour the contents of the catch pan into a five-gallon bucket with a lid.
3. Repeat this procedure with the drain plug on the bottom of the coolant expansion tank; it should be readily visible and accessible from under the car. Finally, locate the coolant drain plug on the engine block. Youll find it just under the exhaust manifolds, near the center of the engine. Drain the coolant and dump it into the bucket. Reinstall all the drain plugs, and tighten each to 8 to 10 foot-pounds.
Refilling the System
4. Prepare a 50/50 mix of purified drinking water and BMW coolant Part No. 82 14 1 467 704, or just buy pre-mixed antifreeze approved for use in this application. Set the heater controls to maximum and set the heater fan to the lowest speed; this will engage the auxiliary heater pump, and flush the heater core of any remaining fluid.
5. Start the engine, and begin slowly adding water/coolant mixture to the coolant overflow tank. Make sure the vent valves remain open, or youll end up with air trapped in the system. Continue slowly filling the system with coolant until the coolant backs up into the overflow tank and stays at the "Cold Fill" line.
6. Close the coolant vent plugs, check for leaks and replace the cap on the overflow tank. Check the coolant level after driving about 50 miles; there may have been a bit of air trapped in the system, and it will gradually "burp" out as the system pressurizes. Add coolant as necessary to reach the "Cold Fill" line on the overflow tank.