As posted in your other thread:

^Your water pump has failed. That's why it is loose. That's also where your coolant is coming from. It's coming from the snout of the water pump.

I'm hoping you didn't cook the engine... m54's do not like being over heated. Nor does any other BMW engine actually. My sister in law just cooked her m54's head gasket (01 330i) after loaning her car out to a brother in law. Bad move.

BTW, I also subscribe to the cooling system over haul anytime a car is over heated. Or around 120,000 miles as posted above. I prefer to be able to get in my car and drive it cross country whenever I have to... not worry about a radiator hose, heater control valve hose, water pump, etc. failing on me while I am 1000 miles from home.

Have had 13 or 14 BMW's (4 currently) and love these things. Most recent purchase is our 2005 4.4i X5 Sport.