|One Man Bleeder review by David Zeckhausen on 2002-09-29 at 08:01:31|
I don't like
the concept of a 1-man bleeder 'cause it doesn't give you as good a bleed.
There are several different types of devices which all claim to be "one-man
bleeders" and I'll tell you what I think of each:
1. MyteVac suction pump - don't bother! The reservoir is too tiny on this device to allow it to hold enough fluid to bleed the brakes. You'll find your self emptying the reservoir every couple minutes. And it doesn't generate enough vacuum to pull out any bubbles that are clinging to the walls of rough inner castings on the caliper or bubbles that need to travel any distance downhill. This is simply a very frustrating tool to use.
2. Vacula suction device (or any venturi-based device that you hook to your air compressor). These devices are slightly better than the MyteVac, yet they still don't generate enough force to effectivly remove bubbles. Also, air leaks past the rubber boot, making it impossible to know if the stream of bubbles running down the plastic tube came from your brakes or came from the imperfect seal around your bleed screw. I use mine as an expensive vacuum cleaner to remove extra fluid from the reservoir before I bleed the brakes "properly" with a different technique.
3. SpeedBleeders. These devices are 1-way valves which permanently replace your caliper bleed screws. They claim to allow 1-person bleeding, but don't really work well for a number of reasons. I've installed about 10 sets of these and have found a failure rate of nearly 50 percent. The "1-way" valves too often aren't really 1-way and stuff gets sucked back into the caliper between pumps. Another reason I don't like them is that, if you are in the car pumping the brake pedal, there's nobody watching the plastic hose between the SpeedBleeder and the catch bottle. You don't know when the air bubbles stop coming out, you can't tell when the old, rusty brake fluid has been flushed and new, clean stuff is coming out. And worse, if the plastic hose pops off the SpeedBleeder, you will be pumping brake fluid all over the inside of your wheel well and possibly onto the side of your car. (Brake fluid eats paint!) Finally, the SpeedBleeders don't generate enough of a "jolt" on the fluid to knock loose the pesky bubbles clinging inside your calipers. You need a 2nd person cracking open that bleed screw slightly AFTER you push on the brake pedal. And that would totally eliminate the need for SpeedBleeders and you would simply be back to an old fashioned manual bleed.
4. Pressure bleeders - fluid type. These use brake fluid in a large plastic or metal container and pressurize the car's reservoir with brake fluid. The benefit is that you don't need to stop to refill the master cylinder reservoir each time it runs low. And you reduce the liklihood of getting air in the system because you ran low on fluid. The downside is that you waste a large quantity of brake fluid since, once you open a bottle, it should be used right away or discarded. Excellent for replacing fluid. Simply pressurize, then crack open the bleed screw and wait while the fluid is pushed out into your catch bottle. But, unless you also combine it with a traditional "assistant pumps the pedal while you crack the bleed screw open" bleed, then there won't be enough of a "jolt" to knock loose all the bubbles.
5. Pressure bleeder - compressed air type. This is simply a metal cap with a fitting for your air compressor. The better ones have a built-in pressure guage and an adjustable pressure regulator so you can set the pressure to 20 psi. If you go too much higher than 25 psi, you will blow the reservoir off the top of the master cylinder and I can't even begin to imagine the mess that you will have to clean up before your paint is dissolved by the fluid! (You can blow the top off with a fluid type pressure bleeder too.) The compressed air type of bleeder is my preferred choice since it is compact, easy to take with you on a trip, and doesn't waste any brake fluid. I find that I can usually do the front brakes with one fill of the master cylinder reservoir and the rear brakes on a 2nd fill, meanining the inconvienience of dropping the pressure to zero, taking it off, refilling the reservoir, and then repressurizing is really minimal. However, I do NOT consider this to be a 1-man brake bleeder because I always use an assistant to pump the brake pedal while I crack open the bleeder screw. Combining the pressure bleeder technique and the traditional bleeding with an assistant will consistantly give you the best bleed and the firmest brake pedal.
I strongly advise you to avoid the shortcut of any "1-man bleeder" system and do it right. You'll be much happier with the end result.
Hope this is helpful.