Engine Cooling problem
2003 Volkswagen GTI 4 cyl Two Wheel Drive Manual 60000. Miles
My car started overheating last night. The AC went warm and I looked up and noticed my temp gauge almost in the red. I pulled over and let it idle and within 45 seconds temp gauge was back to normal. Started driving same thing again, rose to red in 30 seconds, same thing when I idle-goes right back down. Seemed to be fine driving under 45 mph and not horsing it. My heat also worked the whole way home. Engine didn't seem abnormally hot. This morning pulled the thermostat and tested it with the boiling water and it opens up just fine. Put a new thermostat in just because I already had one. Took it for a drive and now the temp gauge goes up as soon as I'm driving without horsing it and radiator is blowing cold air and no heat in car? Tested the thermostat once again and it is still opening up fine. No leaks or plugs in the radiator that I can see. Water pump isn't leaking? What else could it be?
There is a possibility that the impeller is broken on the water pump. If you remove the thermostat again you can reach your fingers back and physically feel the impeller. If you can spin it at all then it has broken away from the shaft and needs to be replaced.