Hey everyone, first post on the forums so bear with me as I try to give a layout. I have a 2005 325i, and I've been having problems with the engine overheating. At first, I replaced just the coolant expansion tank and inner thermostat attached with it. When this was performed, I noticed a lot of hard water coming out of the hoses and radiator, so i flushed the radiator out with water until i got all of that out. I then filled the expansion tank with new coolant, and bled the system properly.