Only two times, as far as Im concerned, that a head gasket failing is 1. initial installment when either the head gasket is defective or the surfaces were not cleaned correctly. and no2. which is what i think happened... the timming was off so it overheated releasing all the pressure. problem is they have my car, no one around here knows crap about 300's, and most of all im a woman discussing cars with a grease monkey that clames to be doing this for sooo many years. whos the court going to believe??? I have over $30,000 invested in this car and im feeling so sick to my stomach right about now!!