I recently ran a water hose in my 325ci till only water drained out from underneath the et. I then added bmw coolant in there. The dealership told me 2 gallons would be fine. The idiot didnt have a clue, but 1 gallon was perfectly fine, i had to mix it with a gallon of distilled water. I had to reflush my car. Im lucky i didnt break anything. But for a while i thought i did because i was no longer getting heat. I just kept turning off the car, refilling with coolant until i got heat. I was so relieved. I hope your problem may be fixed as easily as mine, because thats all it took for me.
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