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Old 10-01-2010, 01:22 AM
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cobalt327 cobalt327 is offline
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Homemade Pressure Brake Bleeder

Also works on hydraulic clutches.

Even though I have a MityVac, I find it too small, volume-wise, to be a very convenient way of bleeding all four brakes at the same time.

By now, most guys are aware of how easy it is to make a pressure bleeder from a garden sprayer. Some use air pressure to push the fluid from the master cylinder reservoir through the system. This requires you to keep a close eye on the fluid level so it doesn't run out during the procedure.

Another way is to use a small volume sprayer and pour the fluid into it and pressurize the master cylinder reservoir w/fluid (not air). This means no chance of the fluid running dry- but does mean the sprayer pressure has to be watched and maintained and the master reservoir needs to be drained back to the correct level when done.

I have mixed feelings about saving the brake fluid once it's been poured into the sprayer tank, but I suppose it would be OK as long as the tank was spotless and dry. But not if any old, discolored fluid is allowed to contaminate it- like by siphoning the excess fluid from the master when done bleeding; I would put that into a separate container to be tossed.

I use a rather large (2 gallon) sprayer. This gives a good amount of "run time" before the tank needs repressurized. But instead of pouring the fluid out into the sprayer's tank, I leave the brake fluid in the quart container it came in. I remove the cap, insert the suction hose of the sprayer and that's that. Towels are used all around the quart container to support it and keep it from tipping over. And, for cripes sake, if you make a bleeder like this- keep the wand- just unscrew the tip, so you can turn it off and on at will. A couple of the tutorials show the whole wand cut off and I believe that's a mistake.

There are several tute's online, here are a few:

http://faculty.ccp.edu/faculty/dreed...eder/index.htm

http://www.bmw-m.net/TechProc/bleeder.htm

http://www.bayarea02.com/techtips/brake_bleeder.html

My question is: Is it more effective to push the fluid from the master down to then slaves/calipers, or to push the fluid in from the calipers/slaves back up to the master?

What I'm leaning towards is to go from the wheels up, as this would tend to be the way gravity would be helping more than going from the top, down. Or am I missing something?

If pushing fluid from the wheels to the master, the master reservoir will tend to overflow and will need to be periodically partially drained w/a baster, or by a lid plumbed w/a hose barb fitting and line running to a catch can. That is not a problem.

Nor is it a problem to get a leak-free connection at the bleeders- teflon tape keeps them from leaking past the threads and small spring clamps will hold the tubing onto the bleeder teats under the ~15 psi required to bleed with- IF this system (a 1980 Malibu) can be bled from the wheels up to the master, that is.

I'm just not convinced the pedal I have is as good as it could be. Anyone have any thoughts on how or if this will work on my Malibu- or ANY vehicle?
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