around thanksgiving, my 740il was loosing coolant slowly, final figured out it coming from seam of expansion tank. fixed it by mechanic, but while driving home from the shop upper radiator hose came loose. seperated from radiator. put it back on added coolant, bleeded it. same thing happen the other day. took it to mechanic. he could not figure out why there a pressure build up enough to blow out radiator hose. now it's spitting out coolant when i tried to add coolant while idling. my first theory was fan clutch not working properly at idle. now i am thinking blown head gasket sending engine pressure into cracked head gasket then to somewher in coolant circulation. i gotta see if there is white smoke coming out of tailpipe.