serious boost leak problem

[Cirus_93TSI]

iv had a boost leak for a few weeks now, havent been driving the car since. i replaced the TB gaskets last weekend thinking that was the problem, still leaked. so i presure tested it again and the air leak seemed to be comming from the TB shaft. i have a spare TB, so i swapped them instead of chaging the shaft seals.
so i put everything back together, and there is still a loud ass boost leak when driving.
but what i cant understand is when i pressure test everything, after swapping the TB, i cant hear any air esacping at all. but yet as soon as i hit 5 psi driving, there the loud boost leak is. i put at least 15 psi into my entire engine and IC system 4 times in a row, with 2 of my friends listening as well, and no air leaking at all. the pressure didnt even blead off untill we let go of the hole in the bleader for the vacume lines, which i also took of to make sure the noise wasnt comming from the bleader.

i cant figure out why the air isnt leaking when im not driving. its impossible for me to look under my hood while driving, much less tell where its comming from over my engine and exhaust sounds.
i cant think of anything else to do to try and find out where the air is leaking from, short of taking it down to Extreme and letting them look at it, which will cost a ton of money that i dont have.

if anyone has any ideas about this, id like to hear them. cause even though im looking for another 1g awd, i doubt ill even be able to sell this one for what its worth with the nasty boost leak.

 

[Zenja]

Look for holes in stuff like the intercooler/piping/intake manifold.

 

[Cirus_93TSI]

iv been looking for holes everywhere, im planning on taking allthe piping off my frint mount today to make sure everyting is sealed well, since i disconnected half of the piping to swap the TB but left the pther half on.

but what i dont understand is why it holds pressure without air leaking when the car isnt running. i mean, the pressure held for nearly a whole minute, and didnt blead off untill my buddy took his finger off the hole in the vacume line bleader.

is it possible that something like the turbos gasket might be bad, and causing the loud noise and the inability to hit full boost?

 

[5150DSM]

Try pressurizing your system a little more, when you pressurize to 15psi you are only matching atmospheric (14.7psi) conditions. I have found that in order to locate leaks it is much easier to pressurize past the cross-over point into positive manifold pressure...I use 25 psi from an electric bike pump and spray soapy water on all the possible leak points, find the bubbles and you have found your leak. Hope this helps. Good Luck.

 

[Insearchofatsi]

I had the same problem, sounds fine but then when i hit boost its leaking. I couldnt hear it that well over my exahust either but it turned out to be the intake manifold gasket. Its a bi*** to replace but costs 5-10 bucks only.

 

[Cirus_93TSI]

ill check the intake mani gasket, thanks.
and i only looked at the boost guage once, the other 3 times i was putting more air in each time and not really paying attention to the pressure.

i drove it today after fixing another small problem, and it runs like crap.
every time i let of the gas, the bov will open, but the rpm will rise 300-500 rpm before dropping. it has been doing this since the leak noise started, but its not gotten alot worse, it was like 200 when i let off and pushed the clutch in like normal. not it will raise 3 to 400 rpm in gear after i let off and the BOV opens.