[JamesM3M5]

Got a car in the shop here with a weird howling noise under very light boost - like just barely any boost, maybe 1/2" throttle pedal travel under very light load. It howls loudly enough to hear over the radio. It goes away with more or less throttle. Full throttle accel is great, no noise at all. No noise at idle or startup. No oil smoke out the tailpipe.

Thought maybe the diverter was making a noise as you are just starting to build boost - plausible. Got the inlet pipe off the turbo and holy crap! There is about 6-8mm of axial shaft play!! You can pull the shaft forward and back a full 6-8mm! No signs of radial play at all, and again, no oil out the tailpipe.

There's no way that amount of play is normal, is there?!?! How can this turbo still build any boost? How has it not come apart already? And no oil/smoke from the tailpipe?

[JamesM3M5]

Nope, I lied. It DOES have a lot of radial play, too. But it doesn't leak a bit of oil and still built boost normally (stock tune). Very odd. Car needs a new turbo at 59k miles. Everyone else told him the noise was "normal."

[Fernanimal]

This is the exact same problem I have been having with my N55....I have brought it in to the dealership multiple times now and they claim the noise is normal, but they can't explain the "surging" when accelerating lightly. Full throttle is no problem, no noise.