Izzy gets sick

My wife's 3 series -- called Izzy after the BMW Isetta -- got sick a few days before moving to California. The coolant reservoir cracked while she was in traffic on a particularly warm day. She heard/felt it let go and quickly pulled off.

This is a common failure among older BMWs. The plastic reservoir (and many other cooling system parts) becomes brittle with age and heat and cracks. In this case however, it looks like the controller for the auxiliary fan failed causing the car to overheat which caused the reservoir to fail. Izzy has traveled over 150k miles now so was overdue for a complete cooling system overhaul so that what we did. Radiator, hoses, belts, water pump, thermostat, everything.

We were quite lucky, most cars don't survive a cooling system failure on a hot day. Only Kathy's quick response prevented this from becoming a full-on nuclear meltdown. Well done, you have saved Izzy's life.