Trouble bleeding brakes

[05gt]

I did a disc brake swap on my fairlane here a couple of months ago. I finally got he car all put back together, but noticed that the brake pedal felt a little spongy. I had bled the brakes when I first did the conversion, but figured I would double check everything. I got the back passenger side  done with little problems, then moved to the driver rear. After about 15 minutes of me opening the bleeder valve, having my helper push the pedal all the way down, me closing it, and having them let up on the pedal, I'm still not barely getting any fluid out of the bleeder screw. When I bled the brakes a couple of months ago though, it bled relatively fine. Seems like I'm not getting nothing now though. Any suggestions on what it could be, or should I just keep repeating this until I get fluid. I sure do love this car, but I will be HAPPY once it's all done and all of these little bugs worked out!!!!

[gasman826]

Bleed the rear line at the master cylinder.  If you have volumn and pressure, the rear lines have air or an obstruction.  Work your way to the rear bleeding as you go.  I have seen plugged bleeders.

[BWhitmore]

Check to be sure the bleeder screws on the disc  brake calipers are facing straight up (or close to straight up).  Also, check the free end play in your brake pedal push rod.  I had the same problem and these two items were the culprit.

[05gt]

What problem did you have with your brake pedal push rod? I had to use a universal one and cut it down. Wad yours to short?

[BWhitmore]

Yes, too short, I made an adjustable push rod by inserting a threaded sleeve into the existing push rod.  I think I ended up ith about 1/8 " free play. 

[05gt]

This may be a stupid question, and please forgive me if it is, but does piston inside of the master cylinder have a stop built inside of it to prevent it from being pushed in to far by the brake pedal rod? I'm partially afraid of the rod going in to far and damaging something in the master cylinder. Think i'm going to pull the bleeder screw out of the back of the wheel and clean it out real good to make sure nothing is gumming it up.

[Tom S]

... does piston inside of the master cylinder have a stop built inside of it

In most that I have seen the solid piston or the spring will bottom out before the seal so the seal does not get hurt.

I'm partially afraid of the rod going in to far and damaging something in the master cylinder.

My experience has been that you can push it all the way in & not hurt anything.  Never saw one that did get hurt.
https://www.google.com/search?q=ford+brake+master+cylinder+cutaway&hl=en&qscrl=1&rlz=1T4ADFA_enUS408US408&source=lnms&tbm=isch&sa=X&ei=HA36UfO0Bae7iwLXooDgCg&sqi=2&ved=0CAcQ_AUoAQ&biw=671&bih=350
Maybe there is something in here that can help with your bleed problem. 
http://www.classicperform.com/TechBook/BrakeTroubleshoot.htm

[BWhitmore]

If a plugged bleeder screw is not the problem, you might want to look for a kinked metal brake line.  Also rubber brake hoses have been known to collapse internally.  You might also want to bench bleed your master cylinder by either bleeding it while mounted in a vise or creating some short brake lines that return the brake fluid directly into the reservoirs and bleeding the m/c while still mounted in the car.  While bleeding the system it is recommended to always start the bleeding process at the rear wheel cylinder that is the farthest from the master cylinder and make sure the car is close to level.  Speaking of wheel cylinders it is probably a good idea to pull off both brake drums to check for a leaky wheel cylinder.