Hello, this truck is making a loud whine from what sounds like the exhaust behind the turbo. The engine is badged as a Paccar, but looks pretty much like an ISC. Sounded like Turbo at first and after a few of my coworkers also listened, I replaced turbo and actuator and all gaskets. Fired it up and the noise returned.It sounds normal at idle and really screams when revved up. Further listening sounds like maybe EGR cooler area, but cant feel any air or find a soot trail. Just wandering if anyone has run across a similar issue or any tests I can do? Any help is much appreciated.

Neil Trout
Technician
Arizona Public Service
Phoenix, Arizona, USA