Soapy water. Also, a streamer like you find on a kite might help.
Look for areas that have black around them for a post-turbo leak.
More then likely its from the up-pipe being loose, or the drivers' side up-pipe.

 

Yeah check your up pipe to turbo connection mine did the same exact thing and it took 3 try's to get it right. Loosen your up pipe at the headers then align it to the turbo and torque it down. Then tighten the up pipe at the headers.

 

I did tighten turbo clamp before I tightened up pipes to manifolds but I will take it apart again tomorrow and try to put back together

 

ok so presureised exhaust and intake today stuck air house packed with rags up tail pipe listend with stethoscope cant find a leak in exhaust took regulated air in threw boost hose on intake and bagged intake by maf sensor with heavy bag aired to 30 psi cant find any leaks any ideas have a smoke machine coming tonight see if have any luck with that so far no leak tail pipe to air cleaner im stumped

 

Maybe a busted inner cooler hose or boot? Check where the boots connect to the inner cooler I've seen them cracked from over torquing.

 

i pressurized the whole intake system there were no leaks in pipe joints or boots

 

I bet it's the connection at the collector and turbo. Seen it alot

 

Is your turbo spooling easily? I just did oil cooler, and on initial test run my truck had a leak. You could hear it, and she only boosted to 8lbs. Turned out being the up pipe connection to the turbo. Sounded like it was coming from the intake manifold though.

 

it builds good boost between 15-20 but has no low end power had turbo off 3 times and checked connections i smoked the intake and exhaust i can not find any leaks anywhere i am completly stumped on this one

 

This may sound dumb, but unplug your map sensor and see what it does.

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I'll give it a shot what are you thinking this could change

 

The tune I run acts really weird. It wont have any power till the boost hits 10 psi. Then it will shoot off like a rocket.

 

Maybe you have already found its not leaking at the up pipe coming into the turbo but that was my issue. I unbolted the turbo and got a good seal on the up pipe and turbo flange tightened that down them used a pry bar to realign the turbo bolt holes. Leak was fixed on mine. I had to wait for the motor to cool and then start it and put my hand around the collar and then i felt it blowing out also once i got it off i could see all of the soot where it had been leaking. Low end power makes me lean towards the map hose though i know i had that issue when they studded my truck.

 

un plugged it still has loud air leak now when i get on it and let off quick there is a loud whooping noise but goes way when i plug sensor back in i felt around all joints up pipe and intake while its running cant feel any air anyone have any ideas i tried everything i can thing even talked to a 6.0 tech at dealership only idea he had was smoke and i didnt find any leaks with that either

 

Well I completely tore it down again today had the up pipe out of the truck was no black soot in any of the joints copper coated all the joints tightened up pipe to turbo then put bolts in and tightened up pipe together and tightened to the manifolds drove still has loud air hiss under boost I'm lost what am I missing?????

 

Possible up-pipe leaking if its not the collector

 

I had the up pipes off to there were no signs of a leak there

 

are you leaking at one of the egr block off plates. or possibly an intake manifold gasket?

 

I have egr valve still in I will try putting in intake gaskets I guess

 

Sounds like up pipe or turbo clamps.

 

Took all back apart AGAIN!!! Put new intake gaskets and it still leaks and won't build over 18psi boost now what?

 

Finally found it was the POS!!!!! Plastic cooled cac pipe had a crack on the bottom that would not open up or be visible under low or no pressure pulled the metal pipe off my 04 now have to replace that one

 

Nice find.
That's why a lot of people switch to the metal pipe.


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I had the same scenario. I followed zmanns advice. I could have sworn i had the up, y, and all pipes aligned. Removed the turbo and found the egr cooler "slightly off" Threw everything off and had no boost and a slightly noticeable air noise.

 

It wasn't any of my exhaust pipes it was a cracked intercooler pipe