Changing Brake Pad Problem

[68camaro396]

Hey guys / gals,

When I am changing anyones brakes and pushing in the piston in the caliper, brake fluid gets forced out of the master cylinder. Mostly when I have already done one and the piston in already pushed in.



What am I doing wrong and how do I fix it?

[bretcopsey]

The master cylinder should not be full when the pads are worn. Somehwhere along the way someone topped off the fluid level. Brake systems do not "use" fluid, so I never understood the logic behind adding fluid. If your using brake fluid, you can't make up for it as if you were using engine oil.


Anyway, off my rant. Just make sure to siphon (sp?) off some fluid before you change the pads and you should be ok.

[BonzoHansen]

You should be cracking the bleeders open before you push the pistons in, and not forcing fluid back into the m/c. Esp. with ABS systems. Fluid should be flushed every few years anyway.

[Damn True]

Here's what I do.
Right front: Pull caliper (if needed)
Pull Pads
Push back pistons
Install Pads
Install caliper.
Apply brakes to get the pistons back within the normal operating range.

Then do LF - RR -LR.

Reason is that if you have both left and right pistons pushed in you have moved a fair bit of fluid back upstream. This may be the cause of your overflow.....unless someone topped off the MC since the last brake job.

[68camaro396]

Hey Damn True,

Are you saying to completely remove the caliper? I really thing that much work is not necessary. Maybe I am supposed to be cracking bleeders open a little. I have never heard of either way, but if I crack the bleeders then I will definately have to top off the MC and then re-bleed. RIGHT?

[MrQuick]

You should be cracking the bleeders open before you push the pistons in, and not forcing fluid back into the m/c. Esp. with ABS systems. Fluid should be flushed every few years anyway.

word. I've seen alot of master cylinders get wasted because this step was skipped. Removal isn't necassary. When back together flutter pump the pedal to bring piston out to contact pads. Flutter= not past half way point on pedal travel.

[68camaro396]

So what is the easiest way to bleed when it is just you?

I don't have a one man bleeder but I have heard I can just "Gravity Bleed" each caliper. This probably isn't ideal and aside from it taking a lot longer, is there a reason I shouldn't do it that way?

[BonzoHansen]

I usually just crack the bleeders, push the pistons in and tighten the bleeder before I let go of the piston. No air gets in, no bleeding usually necessary. For that little bit, if you were by yourself, gravity bleeding would work fine if you must bleed it.

And yes, you might need to top off the brake fluid. And remember to pump the brake pedal before you back it out of the garage!

If I am going to flush the system, I keep an old turkey baster in my toolbox. I draw all of the fluid out of the m/c, sometimes I’ll wipe it clean, and then add new fluid. Why push old fluid through?

[Damn True]

Hey Damn True,

Are you saying to completely remove the caliper? I really thing that much work is not necessary. Maybe I am supposed to be cracking bleeders open a little. I have never heard of either way, but if I crack the bleeders then I will definately have to top off the MC and then re-bleed. RIGHT?

Only if you need to pull them to get the pads out.

[68camaro396]

Sounds good.
Thanks for all your help....everyone.


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