My 2000 4.0 v8 disco started to overheat slightly so I had it pressure tested and it came back fine. When I checked the coolant hoses they were all hot except for the one coming out of the bottom of the thermostat, along with the radiator. I was woundering which way the water flows through the thermostat. (top to bottom or bottom to top) Could this be a broken water pump? Any help please?