Hows the oil look? You might be hearing the oil draining back into the pan from the head. It some times can sound like something pouring on the ground. But look at the dip stick for water. Also how's the water level? Make sure it's full to the top and leave the cap off. Start the truck and the water should stay right there until it starts to get warm then it should start to over flow, slowly. But if it erupts like a hard night of drinking then there can be a problem. Let's hope not. How much did you pay for it, if you don't mind.