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Turbo shut down noise
2005 F250, 79,000 miles, super clean Oasis, everything functioning great...but I have one concern:
Upon shut down...I hear the typical turbo spool down noises as I would expect to hear. But it seems right before it reaches zero rotation...say 2 seconds before stop...it changes sound and gets "noisy" in my opinion. Not whistle noise...but something else. Like hissing or constant huffing??? It definately changes tone.
Would this be normal or should shut-down be "silent" once down to low rpms on the turbine shaft? I'm guessing the variable vanes are doing something at the end making this sound...which I'm calling harmless.
I'm only familiar with non-variable turbos on Cummins and Duramax engines. Perhaps I need to go listen to another 6.0L to compare.