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Questions about one man brake bleeding

Hi guys, If I put tubing over the bleeder nipple and the other end in a jar with 2-3" of brake fluid, wouldn’t I be able to (after opening the bleeder nut) pump the pedal till the bubbles stop - without sucking in air? One post suggested holding the end up in an arc (an assistant)I’m interested the homemade vacuum jar with two holes in the lid one carrying the fluid from the nipple and the other sucking from a vacuum cleaner( I’ve found that a turkey baster tube wedges nicely into the vacuum hose while the tapered end of the tube would wedge into the second hole in the jar lid.Maybe a little rubber grommet would seal it better. I don’t think the seal must be perfect.Somehow I don’t like the idea of forcing air into the Master Cylinder…Tah…Mike

The best way to bleed brakes is to force brake fluid into the master cylinder. There are inexpensive kits on the market that use the pressure in your spare tire as a motive force behind the fluid. They work great.

Second best way is to use the jar as you describe, but put a vacuum on headspace in the jar. I prefer a vacuum cleaner to the little hand pump mity vac.

The trouble with pumping the brake is that you need to have both circuits open so both halves of the master cylinder can push fluid, and if you have an old master cylinder with some rust in it, pushing the pistons all the way to the end of the bore could be the end of the line for the master cylinder.

Also, when you loosen the nipples, air can leak in around the threads. You can really see this happening when you use the vacuum method, but in that case, you are pulling the air out as it leaks in.

Mike, “Gravity Brake Bleeding” Is Slower, But Works Well For A One-Man Operation. It’s Very Simple.

After you click the link then click on # 7 “Gravity Bleed Your Brakes”.


You don’t need to seal the jar holding the brake fluid. What is important, is not letting air get sucked in past the bleeder threads. The position of the jar helps in that regard. If you have the jar below the bleeder, it’s often harder to draw the fluid back up rather than suck air past the threads. This is why many of the one-man bleeder systems have magnets on the jar to keep them above the wheel cylinder/caliper. The air naturally wants to go up and the fluid down. However, as you probably know, brake fluid is an effective paint remover so resist the temptation to stick the reservior to an exterior, painted panel.

The jar is not necessary. As long as the rubber hose is snug and pointing upward, and the master cylinder is not allowed to go dry, the pedal can be pumped and air will be purged. You will need oil dry to clean up the mess without the jar, though.

You are right, but I have found that the magnets are too weak in many cases. A small piece of wire hooked thru the cap and over a spring coil keeps the jar up in place, and you can use a larger jar.

A little grease around the bleeder threads keeps air from being sucked in there if you are using a vacuum system, but not needed with a gravity bleed.

Basically, I like to gravity bleed with all four bleeders open at once.

There’s this one man bleeder hose with a check valve on the end. You can buy one and follow the instructions. If you’re just bleeding the front you can gravity bleed them with major success.

Just open the valve until you get flow and wait for bubbles to stop coming out. For the back ones, open the valve while pushing the piston back in. Don’t forget to pump em back out or they won’t work for a while.

Buy the Haynes manual to get the real instructions for your specific car.

One person gravity brake bleeding may get new fluid into the system but with a helper pushing on the brake pedal while the other person opens and closes the bleeder valve, there will be turbulence created in the wheel cylinders to stir up and force out debris at the bottoms of the wheel cylinders.

If your brake fluid should happen to be saturated with water, any separated water in the system will settle to the bottom. That is another reason to not use the gravity method.

I forgot to recommend that you not bother with turbulence and water settling because it is just not true.