Horrible sound from boost

[jon6.5]

My 6.5 has a leak. I don't know exactly when it happened but all of a sudden my boost dropped to about 7psi max and anything over 5psi it made a terrible noise like all the pressure being let off somewhere and the fuel mileage went to hell at about 11mpg, just when diesel hit 4.32 a gallon lucky me. Now its worse I cant even make 5psi boost, the noise kicks in sooner, and the millage is still lame. I cant seem to figure out were the problem resides, and do not see any soot tracks from a leak. so any ideas would be greatly appropriated.

[MrDiesel]

You need to figure out a way to pressurize your intake. then it is as simple as looking for it with soapy water. I would only use 15 to psi of pressure though. This is the way we test air to air coolers on trucks at work. although the leaks can usually be felt with your hand easy enough.

[john8662]

Three main places that it it can really leak:

Turbo to upper intake manifold boot, could have a hole in the boot, or loose clamps.

Upper intake manifold to lower intake manifold gasket, this is a gasket between the upper and lower intake, can blow out in a section.

Lower intake manifold to cylinder heads, I don't think this is your issue, but this is another source of a leak.

My bet is on the boot between the turbocharger and the upper intake plenum.

J

[jon6.5]

I picked up a upper intake manifold boot today and plan to install it tomorrow morning I hope that does it for me.

[jon6.5]

well I replaced the Turbo to upper intake manifold boot, and the Upper intake manifold to lower intake manifold gasket and still have the leak, wile I was in there I took the time to clear all the excess webbing left in the casting of the manifold. But back to the leak whats left for issues just the Lower intake manifold to cylinder heads? no other possibility's that you guys could think of?

[DmaxMaverick]

It may not be on the intake side. Check your exhaust crossover and other connections.