the biggest clue that your water pump isn't working as it should is an unstable water temp, does it overheat when your stationary.GTiR_Mic said:Good way to check is if you have power steering. If you dont the belt isnt turning the water pump.
Last time i priced one it was £58 including VATstevepudney said:it's blowing it back into the header tank because it's overheating.
If I were you I'd get a new water pump (bout £40 ish from Nissan) and a new rad cap.