Hey. i have a 1999 328I. and it has cooling issues. it overheats, and the coolant blows up from under the cap. i replaced the fan, the fan clutch, the radiator, all of the radiator hoses, the thermostat, and the water pump. the only other thing that it could be is a blown head gasket. i am wondering how much would it cost to replace it? in just outside Philly area. i don't need to know the exact number but an estimate. thanks you very much.