Boogie's_AutoRama

...or $2 bucks worth of hose.

Really, all those fancy gizmos are absolutely not needed. It is just too easy with a cup and a piece of hose.

crunchyskippy

I had a problem with air entering one of my lines through a poorly made flare. Double check ALL of your fittings and connections. Follow each line looking for small amounts of brake fluid.

Lastly, were you able to "stand" on the brake pedal and have it hold before cranking the engine?

Good luck. I wasted quite a bit of brake fluid during my bleeding episodes after the disc swap.

67mustang302

The best way to bleed brakes is with 2 people, 1 person presses the pedal down BEFORE the bleeder is opened. It's called pressure bleeding, and what it does is compress any air in the line and force it towards the calipers prior to opening the bleeder.

Boogie's_AutoRama

Not trying to be disagreeable 67, but that is probably the worst way to bleed brakes. I know, I know, I used to do it like that and it does "work".
But the chances are high of sucking more air back in.
Plus it's messy. And brake fluid is bad for paint, rubber, and tastes bad.
(unless you're doing it with a hose, so why not do it right to begin with)

The hose & cup method is tried and true with virtually zero chance of air getting back in.
Bleeding brakes this way is really just an extension of bench bleeding the master cylinder.

The advantages really show up when you're trying to bleed a finicky clutch slave cylinder. I remember fighting one of those back in the day. I was about to give up and go buy one of those bleeder do-hickeys mentioned earlier when my Dad came along and showed me the "old-school" trick with the hose & cup.
Never needed help bleeding brakes since.






.

67mustang302

If you want to avoid getting air back in you can use check valved bleeders. But when someone presses the pedal down, you close the bleeder before they let up; that way it only pulls fluid from the m/c. That combined with a rubber hose over the bleeder nipple, means there's enough fluid in the hose to prevent air pulling back into the system after the pressure equalizes to atmosphere.

One problem with just using a rubber hose into a cup is that air bubbles can remain in the high point of the hose and when you let off the pedal can pull back into the caliper. When the m/c piston retracts, the brake system pressure drops below atmosphere; that will pull whatever is in your bleeder hose back into the caliper. You don't want that also because brake fluid absorbs water....so when you bleed brakes you want all the old fluid out so you have only fresh, unsaturated fluid.

The reason for pressure bleeding is to compress and force gasses towards the bleeder valve. Without pressure bleeding, gas bubbles can remain in high spots of the system and fluid can flow under/around it in the region the gas is in. Pressure in the system compresses/coalesces gas bubbles that are more easily carried towards the bleeder valve. Another reason for pressure bleeding is that it reduces the risk of fluid aeration from there being no system pressure when the pistons are moving (fluid foaming from mechanical motion).

The hose-cup method is certainly easier, and has less chance of mess; but brake system and hydraulics manufacturers advise to always pressure bleed systems whenever feasible.

musnicki

In addition to the method stated here....periodically go out and give your brake cylinders light taps with a rubber mallet in order to dislodge air bubbles.

Also, it's not just when you turn the car on. When your pressing the brakes a lot, pressure builds up in the system. If you don't touch the brakes for a few minutes and then press the brakes suddenly, they'll go to the floor.

67mustang302

Actually, that's a sign the calipers could be misaligned. The brakes should always be right at the top, if they're not then that means air is getting into the system or pistons are being pushed back by something. Then there's knockback, which you can get after hard corners in some systems.