It has been an irritation since new but when the engine is running with bonnet up once in 15 seconds or so I hear one slurp/gulp noise which appears to sound from the expansion bottle area. The engine this morning was only driven until the blue light extinguished on the dash so the engine was not hot just warm. I have wondered to drive to the dealers for them to identify the noise but knowing Sod's Law nothing will sound. I have had no water level drop and no coolant added and it has always been level with the markings since new. Does anyone else have this noise? Engine is 1.2tsi 86bhp.

@edbostan - Well, on the presumption that the coolant level shows as right, how good is the heater?

The heater is fine with plenty of hot air. The car is 4 years old done 26k and two continental trips including alpine roads with no overheating problems. I might mention it on the next service.

@edbostan - Well it's not an air lock in the heater then. I'm out of obvious ideas.