Topic: Enematic Brake Bleeding system - bleed brakes yourself for < $2
I recently wanted to replace my brake cylinders and bleed my brakes myself, and I have heard about this device you can use made by MOTIVE Products that uses air-pressure in the brake fluid reservoir, and also devices that suck the brake fluid out, but I thought, you know, it doesn't seem like it would be that difficult to come up with some relatively cheap way to bleed your brakes yourself. Well, following is the technique I came up with. It costs less than $2.00 and I think John Muir of Idiot Manual fame would appreciate it. First of all, we have a photo of all the components of my Enematic Brake Bleeding System laid out on a piece of paper (note - the steel rule is not part of the system but is just to give reference against which the tubing's length can be judged):
I wanted to find some kind of container that had a nipple that would just fit tubing that would be the perfect size for the brake bleeder valves, and I came upon an enema bottle. This has just the right size to fit that tube. You need one of those bottles. You need a short piece of plastic tubing (what I've used is 5/16" Outside diameter and 3/16" Inside diameter vinyl tubing). What you want to do is, attach this to bleeder valve and have it the right length such that it is always going up from the end of the bleeder valve, and it should be as short as possible to get to the enema bottle's opening (I used 3½" long tubing for the front-left wheel). When you bleed the brakes, you are essentially pushing all the air bubbles out. So, as soon as the brake fluid leaves the end of the bleeder valve, if your tube is going up, the bubbles that exit there will have no way of getting back into the system. At first I thought that would be good enough. But there are 2 problems. One is, it isn't necessarily true that you can push enough brake fluid through the system with just one push-down of the brake pedal (when you are bleeding any one particular brake) to force all the air bubbles out the bleeder valve (it may be true for the left-front wheel, which is the one I am demonstrating on here, but what about the rear wheels, for example). Another thing is, I wanted this brake bleeding system to be able to totally replace the old brake fluid with the new. So I needed some kind of one way valve to let you keep pumping on the brake pedal. The idea I came up with was, you would have some kind of small metallic cylindrical thing within the plastic tubing (I originally thought of using that little piece that comes on top of new spark plugs) with a small steel ball that would sit on top of it. This I thought would keep the liquid coming up, but would prevent it from going back down. However, once I found the enema bottle, I looked inside the top part and saw it was made just right to have a small (I used 5/16") steel ball put right down onto its sloping surface, and this would do the job of being a one way valve. I put it all together and it did seem to work.
So first you empty the enema bottle of its contents:
Then you attach the top of the bottle to the bleeder valve via a short piece (I used 3½" long) of tubing and you mount that top of the bottle to some part of your vehicle (I used some thick steel wire to mount this to tie rod end). Then you open the bleeder valve. Now at this point this system's valve (steel ball) has not been added:
Here I add the steel ball to create a one-way valve:
Now, here I need to attach the bottle to it's top. I hadn't thought about this until I finally went to try this out, but you really need to deflate the bottle here as you are screwing it into it's top, because I assume that if you didn't, then when you tried to fill the bottle with brake fluid, there would be resistance from the air already in the bottle:
Now here is what the bottle looks like after you have pumped the brake pedal a few times. Notice that it is getting filled with brake fluid and the brake fluid is remaining in the bottle (without the steel ball, I assume the brake fluid would be pulled out of the bottle back into the wheel cylinder when you released the brake pedal). Now, this isn't quite as good a system of bleeding the brakes as those others I mentioned up at the top of this post, since you don't get to be right there where the fluid is coming out to see if there are any more bubbles coming out. But, I still think this should work pretty well. After pumping the brake the required number of times (it would be nice to know how many times is enough for each of the wheel cylinders), all the air bubbles should have been pushed out. Since the tubing coming out of the bleeder valve is going UP into the bottle, any bubbles that exit the bleeder valve with be pushed up into the bottle and will not be able to return to the system:
Now I have to admit I have only tried using this on the front-left wheel. I was going to do all the wheels (replace brake cylinders and bleed them) but I found I couldn't even get the lug nuts off the front-right wheel. But anyway, if anyone knows any problems they think might crop up using this system, it would be nice to hear about them.
