Just a noob question really. How can you tell if you water pump isnt working? My car over heated and i noticed the rad fans wasnt working. The coolant was boiling over almost in the expansion tank. Left the car to cool down and it was fine. Ive just bought a new temp sensor as that wasnt working and was thinking maybe the termo stat is shot but if it was then surely i wouldnt get hot air in the heater fans would i? Anyways just wondered what to check as ive checked all fuses including the ones ontop of battery and they are fine. How would i check the rad relay is working and if it is, then what else should i check?