The idea for the PowerBleeder came from me having to bleed my brakes when I did a rear brake job. I wanted to replace the flexible hoses as well since they've been on the car since it was new, and I figured that since the brake lines were original to the car they were due for a change. After a couple of prototypes and some false starts, I came up with what I call a PowerBleeder. Here's how I came up with this helpful addition to my toolbox.
I had used a Mityvac for bleeding brakes before, but it had some problems. If you wanted to do a complete flush, you had to empty the small containter many times. The small container tended to tip over as well. So I fabricated a home made contraption out of a canning jar, and some ABS sheets I had laying around.
In it's simplest form you can just take any Mason jar and drill a couple of holes in it an epoxy two plastic hoses. It will get the job done. It won't cost much, but it looks so cheesy. I wiggled the plastic lines and I heard a small "crack" and the epoxy didn't want to seal to the plastic tubing, and it separated. The hoses still held vacuum, and I could have glopped some more epoxy and then been careful not to jossle the tubes when I bled the lines.
So I decided to kick it up a notch and fabricate one out of ABS plastic. Much nicer looking, much less cheesy. Here's some pics of what I came up with. It worked very nicely, and with a long hose attached to the jar, I could pump the rear brakes from the front of the car, and watch the master cylinder level without having to pump, look, pump, look, well you know what I mean if you have ever done it.
As luck would have it, the pint Mason jar top, fit a Best Foods Mayonaise Quart jar, so that gave me even more capacity that I had planned on. The original ABS setup worked fine the first time around, but had some small leaks. It turns out there was no way to seal the ABS to the glass jar to create a vacuum. I tried gasket material, cork but nothing sealed it completely. It was good enough to bleed the rear brakes, but there were still bubbles in the line from the small leaks. The bubbles didn't hurt the bleeding process, since they came after the brake lines. Much to my disappointment the brake fluid attacked the ABS and the whole thing fell apart in a week. I wasn't sure if the ABS would hold up, and as it turns out it didn't. But the design was OK, the original ABS materials, not so much.
So I had to fabricate the next version out of something tougher than ABS plastic. The answer was kinda staring me right in the face. You can see that I used a jar lid to trace out the ABS originally. Well the jar lid was made of metal, and it had a rubber lip to seal the jar also. All I had to do was to fabricate something to attach to the metal top. Aluminum was my first choice. It's easy to work with, and the brake fluid wouldn't affect it. So I used the original ABS version as a template and fabricated one out of aluminum.
Now I could have just disconnected the flexible line from the hard line in the front, and do it like I did the rears, but I had a better idea. The problem with bleeding from the bleeder screw with a vacuum pump is that you suck in a lot of air along with the brake fluid. It stands to reason because you have to crack the bleeder screw just a bit, to get the fluid to come out, and the air is sucked in past the threads, and where the hose connects to the bleeder screw. It doesn't do any harm, just slows down the process, expecially if you use a hand pump. So I came up with the idea of screwing something into the bleeder screw hole, and sealing it to the brake cylinder so you could pump out the brake fluid without sucking in any air.
My idea was to cut off the end of the bleeder screw, and then adding a rubber or nylon washer to seal it to the master cylinder. So off to Lowes to get some parts. I got some rubber washers, and some steel ones as well. Then this could be screwed into the bleeder screw hole, and then attach the vacuum pump and you would esentially have a sealed system. In theory, that is. In practice it turned out to be quite a different story.
I decided to test it out on the front brakes since I already did the rear brakes. Well, to be honest the new bleeding system worked fine, but I made a real big mess.
Here's what happened. When I did the rear brakes, I noticed Toyota was smart enough to put an upside down "U" where the hard line meets the flexible line. So the brake fluid has to be pushed up and over the "U" to the brake cylinder. So all I had to do was to remove the flexible line and slip the plastic hose over the hard line, and I didn't spill any brake fluid at all.
The regular way you do bleeding is to put the hose over the bleeder screw, open it maybe 1/8 turn and start the vacuum pump, or have somebody in the car pumping the brakes while you loosen and tighten the bleeder screw. Well since my new whiz bang system requires that you remove the bleeder screw entirely, and replace it with the modified one, fluid starts to come out immediately. I knew that it would, so I put newspapers on the garage floor, and used lots of rags. But this new system required a bit more fiddling, to get everything hooked up. Remove the bleeder screw, drip, drip, drip. Start the new shortened bleeder screw, drip, drip, drip. Brake fluid on nitrile gloves, slip, slip, slip. Well fiddling time equates to dripping time. By the time I had everything in place the brake fluid was running down the tire, the hose, the newspaper, and all over me. Mr. Gravity took over the instant I cracked the bleeder screw and didn't stop for a second, and there was brake fluid everywhere.
Once I got everything hooked up, it went fine. And I was really surprised on how well the new system sealed up, and I got good vacuum, and was very surprised on how much vacuum the little hand pump could pull. In five minutes I was able to fill the quart jar 3/4" full with just the hand pump in about 6 minutes.
But I had to be honest, this needed some work. First off I had to come up with some way to remove and then replace the bleeder screw and not make so much of a mess. Did I mention that the plastic hose came off the bleeder screw when I was pumping ?? That really added to the brake fluid mess.
So I came up with this short length of tubing, call it a pigtail. To keep the original bleeder screw from dripping brake fluid immediately, just put this cap over the screw before you unloosen it. Duh. I also used the smaller diameter tubing for the short length. It fit's very tightly over the shortened bleeder screw, and fits easily inside the larger tubing. It makes a very good seal. I found that this was easier than trying to remove the tubing from the brass barb fitting. Once they get on, they are a bear to get off, especially with brake fluid everywhere. I took a piece of wire and twisted it around the hose where it joins the bleeder screw to secure it from coming loose and to seal it. To keep the brake fluid from draining out after you screw in the pigtail, I added a rubber cap to the end of the tubing.
So now all you have to do is to bunch up a rag under the bleeder screw on the caliper. Remove the rubber cap on the bleeder screw, then using an 8mm socket, or the closed end of a combination wrench, (not the open end
) or a flare wrench. Just crack it a bit to break it free. Then replace the rubber cap to keep the brake fluid from running out all over the place, and then remove the bleeder screw.
Put your finger over the hole, (duh) take the pigtail with the shortened bleeder screw on it, and screw in the pigtail. If you're quick, you won't spill too much brake fluid. There's no need to use a flare wrench on the pigtail fitting, an open end wrench is fine, since you don't have to tighten the shortened bleeder screw very tight. Just enough to seal it. If you wrench on it too hard, you will distort the rubber washer, and introduce leaks. Here's what it looks like when the pigtail is just a bit loose. You will see air bubbles in the line, pic on the left. Just tighten it up a little bit, and the bubbles will go away, and you have an air tight seal. Pic on the right.
As an added measure, I clipped some hemostats to the tubing before I removed the cap and installed the main hose. Once you are sure everything is hooked up properly, then you can start pumping. When I did the front passenger side, I spilled just a little fluid, but when I did the driver side, I had perfected the switch-er-roo a bit and didn't spill hardly any brake fluid.
Be aware that if everything is sealed properly you will be able to suck a lot of brake fluid in a very short amount of time. Monitor the master cylinder carefully. It won't take too long to empty it. Ask me how I know that. I took a video of the process, and I'll have to admit it is the most boring video you will probably ever watch. The video is about 3 minutes long, and it was taken about 3 minutes into the bleeding process. Notice the level of the brake fluid in the jar behind the round pressure gauge. At the beginning of the video it is just touching the bottom of the gauge and at the end it is higher. Also notice how slowly the vacuum bleeds off on the gauge. When the dial is at the 12 o'clock position it represents 15 in. I only had to pump it once during this three minute period. Notice also that every once in a while there will be a bubble in the line, and you can see it move slowly. If you've ever done this with a hand held vacuum pump you might remember that there is a constant stream of bubbles in the line. This sealed up so well that there are virtually no air bubbles introduced anywhere in the system. At the end of the video you can see that about one inch of fluid was added to the jar.
Once you are satisfied with the amount of brake fluid flushed, depress the valve on the vacuum pump to release the pressure. Then remove the bleeder line from the pigtail, and cap the pigtail with a rubber cap. Unscrew the pigtail and re-install the stock bleeder screw and hand tighten it. The brakes at this point should be fully bled, but just to be on the safe side, attach the bleeder line to the bleeder screw. Then pump up the vacuum pump to say, 15 inches, and then just crack the bleeder screw open 1/8 turn or less. You should see some fluid and a steady stream of bubbles come out of the bleeder screw. Don't freak out, the air is coming from around the threads in the bleeder screw. After 10 seconds tighten up the bleeder screw, remove the bleeder line and tighten up the bleeder screw with a flare wrench or a closed end wrench. Top off the master cylinder and you are done.
You need to keep a close eye on the brake level in the master cylinder. I removed the filter for this bleeding process and used a wide mouth funnel that fit nicely in the master cylinder opening. If you don't pay attention, you will hear a gurgling sucking sound, and that means that you let the level go to low, and will have to get all the air out of the lines from the master cylinder. NBD, because you can suck out a pint of fluid in no time. Just watch the level carefully. When you are done, don't forget to replace the filter and cap.
Now I've got something that makes bleeding brakes a whole lot easier than the way I used to do it.
Maybe I'll bleed my brakes with every oil change.