You have not given us much information but they this. Park the truck on an uphill after you have it warmed up. Make sure the coolant overflow tank is full. Let it cool down and check the coolant overflow tank. If the level dropped refill it and do this again. It will stop drawing down the overflow tank when its filled the cooling system. These motors get air trapped in them and it takes some time to get it out. If you can find a vacuum coolant refill system like better cooling repair shops (radiator repair) have it will get all the air out the first time. I had this done on my Honda. That cooling system supply line goes from the bottom of the rad up over the trans then up to the water pump near the timing belt system. A really sucky system for sure... /ubbthreads/images/graemlins/smokin.gif