I have a 06 CE 300 special ed bus in my shop . This has the VT 365 . I know POS ! Driver came back from her run Thursday night and said bus is making a loud noise . I brought it in and the noise is a high pitched whistle like a steam kettle .I thought turbo leak . I checked all the hoses and even pulled all of them off and still a noise . I thought Alternator and water pump . Took the belt off still there . I put the belt back on and when I started bus up . Noise came and slowly disappeared . So I left in the shop until Monday . Started bus up and slowly noise went away . So I told the driver it was okay and she came in shop and said noise is still there . I tried running all the engine with my stethoscope and I can't find the noise . I even went so far as to remove all the turbo hoses and see if noise is coming from the turbo . Any ideas ? Is there a way to pump air into the intake so I can see if maybe a intake leak or hose ?
We had a reman Maxxforce DT that would scream and we thought the same things you did. Ended up being that there were 2 bolts that bolt the turbo to the manifold that weren't there and it was causing a nasty noise. I'm not sure how the 365 is setup, but perhaps is worth a look. And as far as pumping air into the intake, you can always try a smoke machine.