Bleeding air out of master cylinder

[greenleg88]

hi all,

2000 impreza outback sport. 175k miles. 5mt

 

I changed a rear left brake line on the car and bled the immediate air out of the that corner. Before i got to topping off the fluid, i drove it. i believe that when i braked, a gulp of air was pushed into the master cylinder causing my pedal to feel mushier than when i first changed the line and bled the air out.

 

 

Is there a way to bleed the master cylinder without removing it from the car?

 

If so, will cycling fluid through the master cylinder and out of bleeder screw for a long time be sufficient for bleeding the air out of the master cylinder? if that is the case, which one? i understand the bleed order is front right, rear left, front left, rear right; by that logic, i assume the front right is where i should do it...

 

Thanks in advance!

[idosubaru]

just like you said - no need to remove or bleed the master cylinder itself, there is just air in the lines that will come out if you bleed the lines. bleed all 4 corners in the proper order and you'll be done assuming everything else is golden.

[davebugs]

I love my Motive Pressure bleeder for times like this.

[Rooster2]

Some years back, I bought a "one man brake bleeder" kit for cheap that works well. It is prolly available at Harbor Freight tool store. Makes bleeding really easy.

[davebugs]

Some years back, I bought a "one man brake bleeder" kit for cheap that works well. It is prolly available at Harbor Freight tool store. Makes bleeding really easy.

 

A lot of these "suck" a Motive "pushes".

 

When air bubbles I always use the Motive even if I have a helper. I'd think the Motive helps keep the bubbles whole where the pulsing of pumping may break it into smaller bubbles.

 

And sucking - well - air expands a lot so if an air bubble I just don't see how sucking can be as effective.

 

A Motive costs a little more and you can(and should) get the Subaru MC adapter. But I believe it is the best way to do this especially on a car with ABS and air bubbles.

 

There are procedures on how to build one from a pressure sprayer from the hardware store. Sometimes it's just sturdier solution to buy the real reasonably priced solution rather than rigging something up. The Motive was one of those devices for me.

[robm]

I rigged up a vacuum bleeder for a Chevy Vega I had, that would not bleed when replacing the master cylinder. (For some reason, it would only do one squirt, then no pump no more.) I found that the vacuum bleeder could suck air in around the threads of the bleed screw. So I sucked on it till clean fluid came through, then gave it a couple of half squirts, not to the floor, at each corner. The result was clear fluid with no bubbles in the last half-squirts, and no mush in the pedal.

Edited April 26, 2012 by robm

[1 Lucky Texan]

may as well cover all the options - anyone using these?, I might buy some;