I learned something this weekend. BMW radiators have a lifespan of about 5 years 100K miles. After that they get soft and blow out pretty much the same way yours did. Mine was on it's way and in fact I broke the overflow port and had to have a new radiator put in. Glad I found mine in time. So for all you people out there with the original radiator have a look at it to avoid the unpleasent explosion that ensues.