Volvoists, et al

Now that I have spent the last week or so wrenching on my '87 B230 FT 740 Garret Turbo, the exhaust manifold gaskets are sealed tighter than a bullfrog's sphincter muscles, the car is now running and running quite well after suffering a fuel polluted oil system that prevented the car from firing. I am looking for specific advice about doing a pressure ducting system leak test.

I want to know if you guys know a way of testing the integrity of the entire vacuum/pressure system while it is all still installed in the vehicle. I am very familiar with the elements within the sytem and have read, studied and understand the Turbo FAQs as they address the vaccum/pressure leak symptoms. Mine are exactly as they are defined in the FAQs (bogging, intermittent non linear boost, running rich evidenced by 20 MPG on the highway and the dash gage constantly rides at about 9 o'clock while the car is ruuning, some black smoke out of the tailpipe and there is a poor boost situation - the turbo gage never gets past about 1 o'clock, the car won't tach over about 3800 RPM
under a load condition).

The bypass valve is not leaking, nor is the line from the intake manifold to the turbo gage. I blew into the tube that goes from the turbo intake to the flame arrester and got some back pressure but not a dead clog, it seemed to The line from the Bypass valve to the manifold and the clamps are not leaking, I sucked on the manifold end of the Bypass valve vaccum line and it opens the bypass valve the way it is supposed to and it holds vaccum. Same with the line from the intake to the dash gage, which surprised me, it looked in rough shape but, didn't leak a bit. I'd like to change it when the weather gets a bit warmer and I will. It's too cold up here to do work that is not immediately required.

Here's the QUESTION:

Is there a way to test the entire system for leaks while it is still installed in the car or do I need to disassemble each hose/element and test them independently ?

I don't mind taking all the hoses off but, if it can be done while the hoses/elements are installede I would be inclined to believe that the leak will be revealed. What do you guys think about this ?

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Rich George