Hi all, currently trying to find the source of a howling noise somewhere in the engine area of my 2004 6.0. It started doing this after I tore it down to do an oil cooler and EGR. I suspected it was the Y pipe, as it didn’t line up to turbo easily when everything went back together. Had to be pulled together with ratchet strap. However, I pulled it back off, reseated, and installed a new clamp and no change. It looked to be sealed as far as I could see. I could not see the underside of it obviously but I think it was fine. Maybe this is where I went wrong? I really can’t pinpoint where it is coming from, all I can figure is it’s on the other side of the firewall from me. It only happens when boost is built up, can’t replicate it in park or neutral. The noise seems to faintly occur around 2000rpm when cruising and when accelerating. But it is very noticeable anytime the rpms drop whether from letting off the pedal or shifting. I believe the sound is more in sync with engine rpm rather than the turbo but it’s hard to tell. It seems to get slightly louder as truck warms up. Exhaust leak? I have visually checked the bellows in the up/y pipe and can’t see soot. I am mainly making this post to get some clips of the sound out there and see if it sounds familiar to anyone. All of the other threads for similar problems have different sounds. Attached are google drive links to the videos since it won’t let me directly attach them.

https://drive.google.com/file/d/1Pqc...w?usp=drivesdk

https://drive.google.com/file/d/1lKi...w?usp=drivesdk

Thanks in advance.

 

Sounds like a leak in your CAC system. Check clamps and hoses at the CAC system. When having the stock plastic tube from CAC to intake manifold (cold side): check for cracks.
At WOT with a lot of boost it will probably blow a hose from the connection.
Take a close look at the upper one at the turbo (hot side)

 

I have already been through the CAC system. This truck has the metal cold side pipe so no worries there. I have replaced the upper hot side boot as it was a little torn up around the edges, and it made no change. I have run up to 3500rpm and 23-24lb, and had nothing blow off.

 

Does it have an cold air intake?

 

Stock intake.

 

Remove airfilter box and pressurize intake system with 25psi shopair (Turboadapter needed)
Turbo is stock too? Any tunes?

 

Yes turbo is stock reman, with about 15k on it. I’m running SCT canned tunes currently on street tune.

 

Well, I ended up readjusting the up pipes for the third time, and at the same time installed my new exhaust (which was an absolute bear, by the way. Having to adapt a 3.5” downpipe to the 4” Diamond Eye system because 4” DP wouldn’t fit my truck.) Previously exhaust was just cut off next to trans, since I had to put old pieces back on to drive until I got what I needed.

Anyways, one of those two things has cured my issue. It’s 100% gone. Very glad I don’t need a new Y pipe!!