how to find boost leak

First thought was the intercooler so I pressure tested it and it is good along with all the boots from turbo to intake manifold.

Any ideas on how to diagnose this? Its only a minor leak right now, it comes and goes throughout the day. Sounds like a high pitch squealing when I pull a hill. I'm sure a smoke test wouldn't work in this case and there's no way building that much boost while sitting is possible. I am out of ideas



Probably should add this is a 98 Volvo with 12.7 Detroit

 

OK I'll Check it closely for cracks thanks

Near the inlet of air compressor? Can you explain? This problem is def related to turbo boost as I can only make it happen with a trailer behind it and getting into boost on a hill. And even then its sporadic

 

Turbo is a somewhat newer BW 171702 and judging by the way the truck pulls hills I believe there's nothing wrong with it but who knows

 

Those got tested with the intercooler and are good.