[Tech] Pressure Flush vs Vacuum Flush of brake fluid

[tberk at sbcglobal.net (T Berk)]

Reading Ryan H's recent thread re: mushy breaks, I was thinking how 
pressure bleeders might aerate the fluid.

I was thinking that normal atmospheric bubbles in the fluid would be 
compressed when pressure was applied through the M/C end of the system. 
(Thx to Al.)

This is in opposition to drawing the fluid out the caliper end of things 
via vacuum applied at the bleeder screw.

Now, I have seen the DIY pressure unit, in fact a lister applied said 
home made jobbie on my own system when I switched fluid over to synth 
and installed SS brake lines. (Brought flare wrenches and later dropped 
off some red poly sway bar bushings too. Scirocco Luv fer ya, that's 
what that is.)

The thing is based on a weed sprayer type unit w/ a hose fitted to a M/C 
cap w/ hole drilled in top. PSI gauge was installed in lid, worked great.

Now, after an eternity of pondering, all of 5 mins, I am thinking 
perhaps the ting to do might be to draw the fluid using a catch jar 
whose inlet was below the level of the fluid inside, & an out let up 
high in the lid to avoid sucking fluid out into the pump.

Part of the issue seems to be the readily available source of pressure 
(heck a bicycle pump could be made to serve) and a dearth of good 
drawing mechanisms.

So, two things:

1) Pressure vs Pull.

2) What to use to draw the fluid out*, DIY wise.


TBerk

*Thx to Al for the link: (scroll down). 
<http://forums.vwvortex.com/zerothread?id=1390239>