The exhaust brake will turn on when idling to help warm the truck up faster. When this happens is will cause a high pitch whistle.

Like this:
http://www.youtube.com/watch?v=2dtQFEAowYs

 

Yea that's normal. The sound I get, which I'm sure is the same ramminit is getting, is much more obnoxious than that and I have stock exhaust. I'll record it tomorrow on my way back to Salt Lake. It should come in clearer since I will be loaded.

To recap, this sound it much more like a whistle or squeal rather than the good ol' turbine sound. The regular turbo sound is there too but it gets drown out by the whistle. It's also much more audible in the cab of the truck than the turbo is. It only comes during acceleration, or deceleration with jake brake on. But for me it also comes occasionally under high idle with jake brake on.

Edit: I wasn't able to get the sound to record. It decided to behave today and only showed up under deceleration with brake on, but was too quiet and high pitched to record. Plus the pallets I picked up were unwrapped and unstable so I had to ease into the throttle like a grandpa.

 

yeah take that whistle you here in that vid times like a 1000 is so loud in my truck its to the point i wont use my jake any more because it hurts my ears i think this weekend im pulling the turbo off and makeing sure its all sealed and a new turbo is droping $4000 into the truck and thats a reman

 

Maybe there's a leak somewhere in the intake system or where the air filter seats. If you have an aftermarket intake, that will/can cause it too.

 

but would that cause exhaust fumes to come under the hood???????????????

 

Mine is fully stock. It's got to be related to exhaust pressure before the turbo or in it. Because the sound only comes when the pressure would be high.

Under acceleration, the intake pressure would be high. But with the jake on and decelerating it wouldn't it be low?

But the exhaust pressure is high in both circumstances due to the jake brake right? That's when I get the sound.

My guess is it's either a leak in or before the turbo, or possibly a bearing. The reason I think it could be a bearing is 'cause my truck had gone 15k without an oil change twice. (boss' negligence) During the second time was when the sound started.

The turbo gets a drip from the engine oil right? Maybe with low oil, it wasn't getting much drip. Or with dirty oil it got hot enough to mess with seals.

I wish there was someone else who had this issue, and fixed it, who could tell us what it was. I can't tear mine apart and my boss will never get it in to the shop.

 

PROBLEM SOLVED!!!!!!!!!!! yesterday while attempting to get a load above pittsburgh pa the problem in my truck got worse would whistle at any time started throwing a hard code p0106 map sensor i couldnt keep enough pressure in the manifold kept throwing my truck into limp mode so i babied it back home to the performance shop i always use strongly recomend did a bunch of test and found that the number 6 5 and 3 exhaust ports where leaking around the manifold gaskets there whre no soot deposits of any kind had to use a special tool that can detect small amounts of exhaust gases so theres the answer take your truck to the shop and have the manifold gaskets replaced and since they already had the manifold loose i told them to put on a pdi manifold for the upcomeing silver bullet 64mm turbo that will be going on it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Hope your boss will let you take it to the shop its an easy fix and mostly labor costs but isdesperitely need to solveyour problem i wanted to say thank you to all for all the advise and wisdom im still learning on these 6.7's and now its time to start playing :icon_party :

 

yup i was just about to say sounds just like a leak before the turbo. since pressure is a lot less after the turbo. Oh and congrats on the new manifold. and turbo. I happen to in the middle of building an old 12valver. Should be done saturday.