2000 Ford Fiesta 1.25 Overheating Problems
Recently purchased a 2000 Ford Fiesta 1.25 and started overheating a few days ago. I pulled over as soon as I noticed the temp gauge was in the red. Had the car towed home to a local garage. The mechanic checked the water pump (said was fine) and changed the thermostat. The engine is still overheating. If I leave the radiator cap on loose then the engine will not overheat. Only when the radiator cap is fully pressurized is the engine overheating and the temperature gauge reading hot.
I'm not that mechanically inclined when it comes to cars and I'm at a loss for what to do next. I'm bringing the car back to where I purchased on Tuesday to have them take a look. I've checked the oil for water/coolant, checked the oil cap, and haven't noticed any leaks or coolant coming out of the exhaust pipe. The mechanic also did a compression check both hot and cold and found everything to be fine.
Anyone have any ideas where else I can look? The car doesn't overheat at idle or slow speeds, but will hit the red pretty quickly moving at highway speeds with the radiator cap on tight. It seems like just steam coming from the engine when I remove the hose connected to the tank.
Any help would be appreciated!