Bleeding the brakes-- won't work.. help!

[delisaj]

I replaced the master cylinder on my TR-6, but, when I bleed the brakes, all I get is air in the lines. There are no leaks of brake fluid, and the servo works fine. I pump and pump the brakes, and all I get is air. I am wondering if I purchased a new defective master cylinder. Any ideas or suggestions welcome.

Thanks, John

 

[shorn]

Sometimes it is helpful to bench bleed the MC before installing it.

 

[bash]

Is the fluid level going down in the master cylinder? I was worried that something was amiss when I refilled my brake pipes, but it just needed a lot more pumps than I thought it would. I could tell that the fluid level was going down in the reservoir so I kept pumping and eventually heard the trickle into the jar. Just a thought.
Alistair

 

[delisaj]

Thanks for the advice. I was pumping alot, and the fluid was not going down in the master cylinder at all. Just air going through the brake lines. Really strange...

 

[Banjo]

Make up some short brake lines that will screw into the MC fittings and wrap up and into the reservoir on top of the MC.
then fill at least till the ends of the pipes in the reservoir are under the level of the fluid and pump till it quits bubbling.
The rest of the system will be disconnected for this procedure as you are just "bench bleeding" the master cyl. This can be done in or out of the car (usually before installed, and clamped in a bench vice,because sometimes the pedal dosen't move the piston in the MC the whole way and makes it hard to get thoroughly bled, thus "bench bleed") and then after getting all the air out of the MC, connect the lines back up, making sure to not let the reservoir go dry, and continue bleeding normally.