If it's raw it could very easily be a cracked head but mroe than likely a blown head gasket. If it's a cracked head you will most of the time notice your oil looks like chocolate milk if it cracked between a water passage and the top of the head where the oil is. But there could be a crack between a jacket and the exhaust port. Do you have dual exhausts? If so which side is it coming from? Did you check your oil?