My brake system won't pull in fluid

Intro: I got a new line and fittings, new master cylinder kit, new seal kit on the caliper. Then went to fill and bleed the system.

Problem: With no lines on, the MC will push fluid out and with my finger covering the hole, will draw fluid out of the reservoir when i release the lever. Plenty of pressure there. Add the line, (not connected to the caliper) pinch the bottom banjo, and pull the lever and I can feel it push against my fingers. Release that pressure, re pinch the banjo and release the lever, it won't draw fluid in, it just sucks on my fingers until I let go.

I don't understand why it will draw fluid out of the reservoir one way but not the other. I don't get why the new line would suddenly make the MC not work right. Any one got any ideas? I'm getting very frustrated.

 

Don't release the end of the Brake Line until the Master Cylinder Fills the Cylinder from the reservoir.

Pull and HOLD.
Pinch the Brake Line Banjo to no let Air back in.
Pump 8 Times and HOLD the Lever tight to the handlebar.
Release the Banjo.
Hold Banjo Tight.
Release Lever slowly.
Hold Banjo Tight.
Pump 8 Times and Hold the Lever tight to handlebars.
Release Banjo.
Close Banjo.
Release Lever.
Pump 8 Times.

Fluid should be at the Banjo with good pressure.

 

Just did that for an hour or two, and still nothing... it just won't draw fluid from the reservoir when the lines are attached. It never releases the vacuum, so I don't think the lines are leaking.

 

quick and dirty solution:
get a few feet of clear acrylic line, 3/16 ID (most bigger hardware stores have it on a spool)... Attach one end to bleeder valve. open bleeder valve just a bit. Pull vacuum on the other end of the line... if you don't have a vacuum pump, just pretend it's a very long straw ... be careful not to suck up brake fluid (hence the extra few feet of line). as you start to draw on it, assist with brake handle. watch the reservoir, make sure it's topped off. pretty soon lines will fill up and all you'll have to do is finish bleeding the lines by conventional means.

 

My kinda guy, Stereo.

Fast and Filthy!

 

What Rick and Stereo said: Basically, you need to prime your pump/MC, and that includes your lines. If you have an air/air bubble in you lines you won't get the pressure required for proper MC function.

 

I drained and rebuilt my front brakes yesterday and was having a hard time getting the system to start picking up fluid from the reservoir when it was completely drained and banjos all connected. I eventually got it flowing by disconnecting the top banjo fitting and use my finger to block the front of master cylinder after squeezing the handle to block the hole, then release the handle. Within a few pumps the fluid started flowing. Refitted the banjo and moved down to the bleeding valve and proceeded with standard bleeding technique. It all worked out. Takes a bit of fiddling though.