boost leaks and testing turbos

[Godzilla32]

hey guys, is it adequate for me to leak test my turbo system as a whole? I have blocked off both intakes right at where the mafs are connected. i have supplied pressure thru the fpr vacuum hose. i found one leaky vacuum hose and one large leak down on the passengers side in the front corner, cant build any pressure. im just checking to make sure i can include the turbos and test as a whole system rather then just ic piping.

[Alak]

Yes. I usually put an adapter on the inlet of the turbo itself and pressurize the whole system. Keep in mind that the pressure may not hold because an intake and exhaust valve could be open at the same time.

Don't try to pressurize your turbo inlet pipes as they are just rubber and will expand and explode. Don't pressurize the system to any more than 20PSI. 15-20 PSI should be more than enough to find any leakage.

[Alak]

Also, block off any crank case vent lines. You dont want to pressurize the crank case by accident.

[Godzilla32]

what crank case vent line should i be blocking off? are you talking about the on that runs from the cam cover down to the black turbo y piece. with the pcv valve on it? I also thought that because the throttle blades would be closed, the positioning of the valves would not effect the test. How long should it hold the pressure for?
Thanks!

[Alak]

Yeah I havent looked under the hood of a GTR for a long time but that pvc line shouldnt be affected you will be hooking your test rig up last that directly to the turbo. The throttle plates are never completely closed as the car still needs air at idle to run. There could be an engine position where valves are not overlapping. Im not sure.

[Godzilla32]

i was able to find a vacuum leak on one of the bleed return hoses by pressurizing the intake tract. I would like to be able to continue with testing the system as a whole including the vacuum lines but I would like to discount the crankcase from it. What lines breathe the crankcase? I'm up to 10 psi and would be sick for weeks if a blew a seal.

[Alak]

Should just be that one PVC hose. Anything AFTER the turbocharger wouldn't affect the crankcase.

http://www.youtube.com/watch?v=AL3jbcrqY8g

Heres pretty much the procedure, on a porsche but its the same premise. Notice in the video, he does not unhook the crankcase vent and as a result the air comes out of the crankcase oil fill cap. I would do the same procedure, only without what he calls the 'J Boot'. I would try and get my air adapter as close to the turbo inlet as possible.