Ok, Guys. I'm back from Indiana and I finally had a chance to take my crossover pipe and y-collector off and look. I think I found at least part of the problem. It's very sooty where the y-collector bolts to the passenger side exhaust manifold (C). Pretty sure I'm not getting a good seal there. What's interesting is that the collector pipe that came on the truck has those slip flanges for both the right and left exhaust manifold joints, just like at (A) and (B). The factory turbo Y-pipe to exhaust manifold joint at (C) has a solid flange.
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The problem that I see, is that the studs on the exhaust manifolds have a nut on them that when everything is assembled, is between the two flanges. It looks like that on the passenger side, the nut is stopping the solid flange from tightening down on the spherical cone. Does this make sense? Do those nuts do anything and can I take them off the studs in the manifold to let the solid flange tighten down? The layout doesn't show it, but is there supposed to be some sort of donut gasket here?
I tried to look up inside the hot side of the turbo from underneath with an inspection mirror to check for melted turbine blades, but I couldn't get a good look. Once I get this flange thing figured out, I'm going to permatex exhaust sealant the hell out of the up pipe slip joint and put it all back together and test. That's less work than pulling the turbo off.
Anybody ever tried Permatex 80697
Copper Spray-A-Gasket at the up pipe slip fit to seal it? Or even
this stuff? Says it's good for 700*F....