Turbo whistle under load?

[BigRedXLT]

Hi all,
I've been lurking and learning for about a year and finally need to ask a question. Is it normal for the turbo to let out a high pitch whistle under load? Towing 8000 lbs up a long hill.... did not always do it, but started on last two outings w/ trailer..... No mods, 2005 6.0, less than 12k miles, outside temp maybe up to 80, factory boost showing 20 (i think)....
Whistle stopped when I let off throttle, so definitely related to being under load. Any ideas?

 

[roosterdiesel]

Sounds like a boost leak to me. Check anywhere that has rubber hoses with t-bolt clamps to connect the metal tubes. If the hoses are oily it's normal from crankcase vent and they are prolly oil soaked and leaking. You can try tightening them first but it may take removal and cleaning of the hoses to fix it if it is a boost leak.

 

[bendog]

Yep, same prob Big Red, same appx weight as you. Whistle starts after quite a while under full load I thought it was rad pressure bleeding past the cap, but I think Rooster nailed it.

 

[RedBadge6.0]

my truck does the same thang but worst, about every time i let of the throttle, and it even does it when i set the cruise control on 65 about every 15 seconds.