like the dumbass i can be, i let air into the master cyl while doing a bleed job.
searching the brakes forum yielded plenty of tidbits, such as:
from the brakes "read me first" sticky:
Originally posted by Andy W.:
Air in the master cylinder, is a big problem that is best handled by a professional with special tools!
and from this thread:
Originally posted by Rara:
One thing that helps to get trapped air out of an already installed master cylinder, is a vacuum source applied to a modified reservoir cap. Otherwise, you can bleed the master cylinder (its messy in car) one circuit at a time, by loosening the fittings just like you would a bleeder screw. This usually works for any car that doesn't have extra bleed screws in the master cylinder from the factory.
Originally posted by Rara:
You need to bleed at the two hardline fittings on the outboard side of the Master Cylinder.
Originally posted by Big Jim:
If you suspect that the master cylinder has air in it, start by bleeding the master cylinder. Follow the instructions above, crack open the steel lines where they connect to the master cylinder one at a time. You should then move to the wheels. The shop manual may have a preferred order, but it doesn't really matter.
i intend to do an in-car manual bleed (no special gadgets). but there's one thing i'm not clear on. do i need to bleed all four lines at the master cyl? why just the outboard two as rara states? do i disregard the two lowers when bleeding the master? if so, why are lowers not part of the bleed process? 
