I recently had my engine and turbo replaced on my Vauxhall Mokka. I am not car savvy and had been on my way to a garage to get the high pitch dentist drill noise checked out. Once I had the car taken to the supplier I waited a month to get it back. When I received it back it was working brilliant, but recently it's starting to make the dreaded whistle again. Is it normal for a turbo to whistle all the time? This is my first diesel so I don't know if it's a normal thing. This time I cannot tell if the noise is noticeable from outside, whereas last time you could hear me coming a mile off with the siren sound of the turbo. It does not make the noise when idle only when accelerating.