How to bench bleed a master cylinder?

[JGood]

I picked up a new master cylinder, and will be installing it this weekend. I've never actually bench bled a master cylinder, so I'm not sure how to do it. I did a Google search and most sites said the MC will either come with a "bench bleeding kit", and if not, I should buy one.


So whats are your tips, tricks, and techniques?

[Teaguer]

You can mount the reservoir on it and then loop rubber hoses from the outputs back into the reservoir .
Then pump the piston a few times until no more air comes out of the lines .

Thats pretty much it , you just want to fill the inside of the MC with fluid before you mount up the lines and have a bunch of air pumping through the system .

[2002maniac]

I'm with stupid^^

I have two ends of a hard line that I fit into the output ports of the MC, then use two pieces of rubber hose hose clamped to the hardline.

[JGood]

You can mount the reservoir on it and then loop rubber hoses from the outputs back into the reservoir .
Then pump the piston a few times until no more air comes out of the lines .

Thats pretty much it , you just want to fill the inside of the MC with fluid before you mount up the lines and have a bunch of air pumping through the system .

OK, 2 questions:

Where did you find a tube that fits perfectly in the outputs, that doesn't leak?

When you pull the tube to thread in the brake line, doesn't that create an air bubble? Air rises, so wouldn't the air in the line work it's way up into the MC?

[JGood]

I'm with stupid^^

I have two ends of a hard line that I fit into the output ports of the MC, then use two pieces of rubber hose hose clamped to the hardline.

Cool, I have a parts car I'll cut the fitting and part of the lines off of.

[TopOfTheLine89]

most places include plastic hardware to block off the holes or bleed them to the reservoir, i guess yours didn't though.

[JGood]

most places include plastic hardware to block off the holes or bleed them to the reservoir, i guess yours didn't though.

Nope. Not a big deal though, as I've already found a solution for that. Just trying to figure out how to keep it air free while removing them and installing the lines...

[JGood]

anyone?

[e30_kid89]

I'm supposed to be able to help you, seeing that i just bench bled a MC 2 days ago in class, but i forget now making me useless.:(

[Mike B.]

Nope. Not a big deal though, as I've already found a solution for that. Just trying to figure out how to keep it air free while removing them and installing the lines...

Don't worry about it. The amount of air that may infiltrate when you remove the lines will be easily removed when you bleed the lines/calipers.

[bwanac]

Put on the reservoir of fluid, and cover the holes with your fingers and plunge it back and forth a few times.

[JGood]

Put on the reservoir of fluid, and cover the holes with your fingers and plunge it back and forth a few times.

what?

Anyway, got it done. It was actually really easy. I put a 25mm in, as it was cheaper then stock. What a difference over the old busted piece of shit!

Thanks guys.

[MIKe30]

Put on the reservoir of fluid, and cover the holes with your fingers and plunge it back and forth a few times.

does this work?


edit: update - made my own. Got 2 bleeder screws that fit the master cylinder at the local parts store, vinyl hose from home depot. screwed in the screws, attached the hoses and looped them up into the resevoir. Pumped the brake pedal a few times and it began to circulate.

I also used a pump to remove the dirty fluid that was initially pumped out. Did that a couple times too, made sure it was nice new fluid throughout. Easy enough.