I just found out I have a blown head gasket. I don't know very much about it but the mechanic took the old cap off and I saw the white plastic melted looking substance inside the oil cap. He checked the oil and said there was not water in the oil which is supposedly a good thing. My truck is a 2005 Sport Trac with 140,000 MI. I had a engine replacement at 70,000 miles so the engine is relatively new. Would you pay for the repair of a new head gasket or trade it in or what? Does anybody know about how much it would cost to have the head gasket replaced in my 05 Sport Trac?