Flushing Brake Fluid - Additional Info

[tberk at sbcglobal.net (T Berk)]

Found some additional info laying with Google:
<http://www.advanceautoparts.com/howtos_tips/automedia_html/ccr/ccr20011001bb/index.html?page=/howtos_tips/automedia_html/ccr/ccr20011001bb/ccr20011001bb.htm>

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One-Person Methods

The automotive aftermarket includes a few products designed to make 
brake bleeding a 1-person operation. The three most common: vacuum 
pumps, pressure pumps and one-way bleeder screws.

Hand-operated vacuum pumps are the most popular for do-it-yourselfers. 
Affordable, these units suck fluid out through the bleeder, eliminating 
pedal pumping. However, air can be drawn in through the bleeders' 
threads if they don't seal tightly, giving the appearance of air in the 
system. Follow the instructions that come with the pump to learn its 
operation and the proper wheel-bleeding order for your car.

Pressure pumps are more expensive than vacuum units and are geared 
toward the professional mechanic. These units attach to the master 
cylinder and pressurize the system?then you simply open each bleeder. 
Some pressure pumps also function as a vacuum. They purge air from the 
brake system and also "bench bleed" master cylinders before they're 
installed.

One scenario in which air can enter the system while using a 1-person 
pump is when dirty bleeders' threads don't seal. If using one of these 
units, consider first removing each bleeder, then cleaning it and its 
wheel cylinder/caliper hole with brake cleaner before reinstalling.

One-way bleeder screws are a fairly recent boon for the lone brake 
bleeder. When opened, their check valve allows fluid out but springs 
shut before air can enter. Best of all, these bleeders are affordable 
and apply pressure.

When all's said and done, brake bleeding/flushing is one of the 
least-enjoyable ways to spend up to an hour. While you're thinking of 
all those things you'd rather do, though, remember that bleeding brakes 
saves human bloodshed.
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