If you’ve decided to pick up the necessary tools and save tons by doing your own brake work, this’ll be your next purchase. While you don’t need something like this to bleed your brakes, it does allow you to do it by yourself. Instead of having someone pump the pedal from inside the car while you open and close the bleed valves from under the car, power bleeders allow you to apply pressure to the master cylinder — the equivalent of having someone in the car pushing on the pedal continuously. It makes bleeding brakes much easier and much quicker.
For the uninitiated: Air + hydraulics = bad. Hydraulic fluid is (mostly) uncompressable, so it transfers force directly through the system. Air, however, compresses easily, so if you have air in a hydraulic system (like your brakes), some of the power you put into the system (by stepping on the pedal) is leeched by the air compression process. You feel this as “spongey” brakes.
The power bleeder pictured comes from Motive Products and clocks in at around $60 depending on your car’s model. While the pump works for all vehicles, you’ll need a specifical cap to fit your vehicle’s master cylinder reservoir. Motive sells a variety of kits for different groups of cars.
And, if you don’t want to shell out the $60, there is a poor-man’s solution: Order (or find at the junkyard) a spare cap for your master cylinder, then drill a hole in the top of it and fit (with seals) a standard air nipple. If you’ve got a small air compressor with an accurate pressure control, applying about 20 lbs to the system will accomplish the same task. Of course, without a reservoir tank like the model pictures, you do have to watch the reservoir and refill it every so often. Make one for each of your cars and you’re good to go.