Yesterday I took my car to get the cambelt and waterpump replaced, Since it came back it has developed a hissing sound. It sounds like its coming from the radiator resevoir. I've checked the pipes and they all seem to be fine. What else could it be? :confused:

Is it when its warmed up? Check the coolant tank cap is on properly or see if it's cracked/damaged

yeah it just seems to be when its warmed. I'll take a look at the tank itself

thanks for the suggestion