I just replaced the radiator on my 540iA ('01, 107k miles). The radiator went last weekend while I was running errands about 2 miles from my home. I shut it off as soon as I realized the radiator had blown and I never saw the temp gauge go above normal. I let it cool for 30 minutes, topped up the radiator and limped home with the heater running on full and carefully watching the temperature gauge for the 2 miles trip. (It never went beyond the "normal" running position.) I had the car towed to my indie shop the next morning and picked it up today with its new radiator and related bits (expansion tank, lower hose, thermostat, etc, etc). When I picked up my car today from my indie BMW shop, the tech pulled me aside and said I might want to think about trading my car soon as he "smelled coolant, saw some smoke and said it didn't want to start when they turned it over earlier today. I have owned the car for 18 months and I enjoy it thoroughly. I am the third owner and have all of the service records on the car. Since I have owned it, I have done any of the "normal" 100k mile stuff that the prior owner had not already done (rebuilt tranny, valley pan gasket, valve cover gaskets, front traction struts, etc.). Call me crazy, but I really do not want to sell/trade my E39. Frankly, I can't think of anything else that I can afford that I would want to drive more than this car. I am looking for any opinions from club members who may have experience with head gaskets and cooling system problems with 540s who can tell me whether I need to be worried about my car. I would also appreciate any suggestions for what subtle symptoms I might watch for to determine if I might have a head gasket problem festering under the hood. (I will watch for obvious white smoke from the exhaust or coolant in the engine oil.) Thank you in advance for any feedback.