I've noticed recently that my Yeti makes a sort of whistling sound when it's first started. I'm guessing that it's something turbo related. It doesn't seem to be happening so much now that the weather is finally warming up a bit so maybe ambient temperature is also a factor. It fades away and stops after driving a few hundred metres.

I'm not particularly worried about it but I did wonder if anyone could shed some light its cause?

P.S. My Yeti isn't actually called Rufus. The thread title is a reference to

.

Could it be an air leak on the turbo jointing that closes when it gets warm/expands?