Coolant flush.

[Alexx]

The coolant on my 1991 BMW 318is needs to be flushed. What do I need to do ?
I will tell you what I am thinking about doing.
First, I will open the expansion tank cap.
Then, I will place a big reservoir to catch the coolant that will be spilled from the engine block drain plug.
Then, I need to unscrew the drain plug located on the lower part of the radiator.
I will turn the heater fan on in order to let the coolant pass thru the heater core to empty the entire system.
After the coolant has dripped, I will need to put the drain plugs where they were.
Next thing to do would be to add some water and a solution that will clean the entire system.
I let it run for 10 minutes and I flush the entire system again.
I will pour more water if the water that comes out from the radiatior drain plug is not clear.
Then, I will need to fill the radiator with a good solution of water and ethylene glycol and bleed the system.

Correct me or help me.

[Alexx]

My main concern is the expansion tank.
In the books, it is written to seperate the expansion tank.
Why would I need to do this and should I do it ?