So, my wifes car has a problem and I think it is the turbo. Even at a stock boost of ~9psi it makes a whirlling sound kinda like a boost leak. Thats what I thought it was so I boost leak tested the car. The car held ~25 psi with a minor leak in one of the vacume lines. I fed the pressure from the inlet side of the turbo. So I took a step back and thougt to myself wtf? I drove the car down the street to listen to the noise again and I noticed another symptom, it would kinda fade in and out of power while it made the noise. So my conclusion is that because the car is holding boost through the turbo, there is not a big enough lead to cause that noise it must be the berrings in the turbo? You guys have any other opinions of maybe something else?

 

if it were the bearings it usualy sounds like a dentist drill, very high pitched. you can take off the intake piping and see if theres any movement in the turbo shaft, there should be none.

 

there is a little of course. The car has about 90k on it. I have no idea of what else it would be.