Youíve got a 2008 Berkshire, so it might not have the same ISB6.7 Cummins engine that I have. From Cummins description of the engine brake on my engine, it works by changing the geometry of the turbines, which would be a pretty complex procedure, as I imagine it is done by a scrolling plate that pushes the turbine chamber in and out. It does provide a variable braking effect.
So, Iím wondering whether my engine brake would completely shut down my engine or just kill my turbo boost. Iíd be able to limp home without my turbo boost.
It sounds like your engine brake has a valve that opens and closes, and that might be on the air intake. I can see how that would really shut you down if it stayed closed.
I hope that some engine expert is reading this thread and will fill us in on more details.