How do you change a heater core in a 1995 oldsmobile achiva?

i drive down the road and the car overheats and it is leeking antifreeze under the car when i shut off the engine. is my heater core blown?|||As stated above, usually if it leaks in the car it%26#039;s the heater core, if it leaks outside the car it%26#039;s a variety of things. i have seen heater cores leak outside, but only in rare occasions. You need to pressure test the colling system to verify the source of the leak and go from there. Check before you spend your time and money.|||if you can smell anit freeze inside the car it is your core ; if it is just under the car most likely a thermostate|||Usually if a heater core is leaking it is on the inside of the vehicle along the front passenger side floorboard. More than likely it%26#039;ll be your water pump or maybe your radiator.|||I AGREE WITH THE OTHER ANSWERS THESE HAVE HELPED ME TOO.