Hi guys, I hope everyone is well. I have an Audi A6 C6 Le Mans 2.0 tdi 2010. The car is beautiful but recently when I give power to the car to speed up etc, the engine has a slight sound like a boiling kettle. This only happens when I am giving power (accelerating). My friend noticed it yesterday, I wanted some advice on what you reckon the problem can be. This noise is slight but you can hear it.