You mean the over pressure vent?

You can tell if there is still some pressure.

If you have 20-30 psi (too low to engage but not enough to run) it will fit in the logic of an obstruction.

With the gauge set on it would be obvious. The key is to test at higher revs not just idle.

If you try to put in 55/250 for example and you get 45/300, definitely blockage.

I'm not sure what the ambient offset is for SA but I'm guessing your low side pressure would be 55-60 vs my 45 in normal human ambient temps.

When you said port I thought at first fill port. I recently had to change the valve in my brother's fill port.

You need to get some dye into your system to remove ambiguity. If it's venting anywhere it will show.

__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)