brake bleeding

[97ranger22bronco]

not to sound obtuse, but is gravity bleeding an effective way to bleed the system? I watched a YT video where a guy cracked all four valves along with the MC cap and claimed that it got perfect results. Maybe I'm behind the times?

 

[Uncle Gump]

I always gravity bleed. It's rare it doesn't work for me.

 

[97ranger22bronco]

Can I do all four valves at once? Or is it best to do one at a time?

 

[Uncle Gump]

I typically do one at a time.

Be sure you don't let the master run empty.

 

[SenorNoob]

With all 4 running at the same time, I don't think I could pour fluid fast enough to keep the master from going dry...

 

[sgtsandman]

In theory, it should work. I've always used s vaccum pump to bleed the lines. I don't know if I would do all four at one time, just because you might not be able to keep up with it and be able to close bleeders at the same time.

I've used that method on the clutch though and it worked well.

 

[mr_manny]

I simply run a clear line from the bleeder screw into a container...would this be considered an OG method?
The submerged line creates a sealed system, allowing you to simply pump until no more visible bubbles. Obviously making sure your master doesn't run dry.
Have done this many times, with great results (especially when your bleeding brakes alone).

I've never tried a gravity bleed.

 

[Uncle Gump]

I simply run a clear line from the bleeder screw into a container...would this be considered an OG method?
The submerged line creates a sealed system, allowing you to simply pump until no more visible bubbles. Obviously making sure your master doesn't run dry.
Have done this many times, with great results (especially when your bleeding brakes alone).

I've never tried a gravity bleed.

That way works too...

The part i don't like about any method that requires pumping the brakes is the it forces the master cylinder seals through the bore of the master that is rarely traveled. Seals get damaged running over pits and deposits that build in that area. I also don't believe it's a good idea to constantly bottom out the master cylinder.

Something else... the master cylinders are duel piston. If you replace wheel cylinders on the rear... there is no way you get air in the front brakes. Do your cylinders on the rear... bleed the rears... done.

You also here people bench bleeding a master cylinder. It's valid... but my bleed procedure for one is to bolt it up... fill it... and let it gravity bleed until both ports have a good drip. At that point... I start the lines on the master... but don't tighten. I then slowly push the pedal down... them use a prop rod to hold the pedal in place. Pushing the pedal down will purge the air in the line connections... and then I tighten the lines. 95 percent of the time I'm done and don't have to bleed the brakes at the wheels.

It doesn't always work... but I've been doing it this way since I started wrenching professionally in 1980. It works well.

4WABS system can be funky... sometimes those require an ABS module bleed function using a scan tool.

 

[Uncle Gump]

One thing I also need to add here.

If a vehicle is equipped with rear drum brakes... the adjustment of the drum brakes is critical the brake pedal height. If the adjust is loose... the brake pedal has to travel further to make the brakes shoes move out to touch the drum. I mention this because many people will replace the brake shoes... end up with a low pedal and think they need to bleed the brakes.

I can tell you that unless you have a leak in the brake system and loosing brake fluid... there is zero chance air can enter the hydraulic system.

I say all this because I hear all the time that "my brake pedal is low" I have air in my lines. I say no... if there are no leaks... you need to adjust your drum brakes.