On the last trip yesterday when I turned on my exhaust brake (inline BD brake, downstream of the turbo) I noticed a fairly loud squealing noise. I had thought it was that the exhaust gas blown a gasket out and is escaping.
Today I got to it and turned e-brake on while idling, and popped the hood. There is a loud squeal from the turbo when the brake is activated, which goes away when the e-brake is turned off. Boost pressure is normal.
I am suspecting that the turbo has excessive wear and moves axially under back pressure, causing the squeal, but I think someone has seen this and maybe I am not understanding it right? My plan will be to replace the turbo but I have an upcoming trip in a day that I don;t want to cancel, and plan to minimize E-brake and risk blowing up the turbo, then replacing it.
The turbo is stock.
Any ideas?
Thanks!
-P

 

With the engine off, take off the intake hose between the turbo and the filter and feel for slack, play, or resistance in the impeller. If it feels snug and spins freely and makes not contact with other surfaces then I'm sure its fine. When installing the Pacbrake there's a mounting bracket/plate which replaces the existing one on the back of the turbo. If that plate or the V-clamp becomes loose then you'd hear the air escaping.