my car overheated a couple of times, I finally fixed the hose and fill it up with water. I drive it and 10 minutes the water in the reservoir is boiling and white smoke is everywhere. The head gasket is probably done. SHould i replace it myself, pay some one, or fuck the blown headgasket on the sohc, and buy another sohc. its a 1989 nissan 240sx stock sohc