Someone with a Series I L67 follow the vac line on the top post of the pressure side vacuum tree. (Sorry, I don't have a good pic...)

That'* right, it tee to the inlet side vacuum manifold (never sees pressure), then over to the vacuum modulator or the evap canistor (now I can't remember which it goes to).

Why on earth does this line always dump a little boost and why have I never noticed this before?

Should you have a check valve on there?

One would think, but I don't see one.

Pardon my dirty engine:

These two hoses connect to each other (I'm assuming you are talking about the left one.)



And then they run here:



Is this what you are looking for? If not... Let me know.. I can go take a peak again.

Oh, yeah, that'* the one. I meant to snap a pic today but got sidetracked. For those not familiar, under where that wiring loom crosses the vac lines, the two with red arrows meet up and continue down to the tranny vacuum modulator. What is up with that? Won't some boost make its way back to the SC inlet?

Anyone put any thought into this?

I will study. And ponder. But I already have a theory.