Brake diagnosis - help

[SouthwestSpider]

This started when I had problems with bleeding the brakes. No fluid to the rear brakes. I've got the compensator linkage disconnected and as high as it will go.
I tried to get fluid from the rear center flex line, without completely removing it, I still didn't get any fluid leaking with the hose nearly removed. The next step is to remove it completely. I have followed the lines and there are no leaks or pinches. So the lines are good - with the exception of the knowing if the center flex line is bad.
When I first started the process I had fluid flowing now it has stopped. I've even tried a vacuum pump to pull fluid and had no success.
Do I start at the master cylinder and remove hoses until I know if the fluid is getting through the lines?
Does the lack of fluid in the main line suggest that the master cylinder isn't working correctly?
How do I test the master cylinder functionality?
The booster works - when I start the car the pedal softens.

[azruss]

do you have front brakes. if not, then the MC probably needs to be filled. When i did my brakes, i had to pre-fill the MC and all calipers before i got any pumping action. I was able to fill the MC by cracking one of the out going fittings and pump til i got fluid. this is a messy job, so put a collection tray or lots of towels below the MC

[dmwhiteoak]

Check to make sure all connections are tight. After my brake overhaul I could not get any fluid to the rear. I found that I had a bad bleeder screw on the left front caliper. I could not tell it was leaking but it was sucking air when brakes were applied. Good luck in your hunt.

[SouthwestSpider]

Fantastic stuff thanks - these suggestions give me things to try.
AZruss - I opened the line on the MC and there was fluid expressed out of the rear hose fitting.
dmwhiteoak - I will take a look at the bleeder screws on the front. Would you think that it's best if I just replace them?
Since you've done a brake overhaul, you would know: my worst fear/dilemma is unscrewing the hard lines from anything - are there any techniques that work? I use the best-fitting wrench I have and still end up rounding the nuts. (ouch) When I took the flex hose off of my passenger rear brake I simply attacked it with a wrench on the hose and vice grips on the hard line. Oddly, it all went well. The center rear flex line doesn't want to give up that easy. I was able to get the line partly disconnected at one end of the flex hose. But where it joins with the hard line it's being stubborn.
Part of the problem is my lack of knowledge/experience with this stuff.

[azruss]

brake fittings are always a pain. best route is to soak good with a penetrant, then use a brake line wrench and clamp it closed with small vice grips. sometimes you dont have the room for this technique. most of mine are rounded off. I just think of it as a knurled nut

[dmwhiteoak]

It surely would not hurt to replace the bleeder screws as they are probely the original and very cheap to buy. On all connections that were broke I would spray some type of cleaner that will bubble as air is leaking through. 409 and windex work well. this is how I found my leak but mine was leaking at the threads not the center of the bleeder.

[SouthwestSpider]

AZRuss - it seems like the best device for these is the vice grips on the 'knurled nuts'.
dmwhiteoak - I should have thought of the air bubble technique for escaping air. Thanks - I'll follow through on that.
I appreciate the ideas.

[SouthwestSpider]

Well - I checked the hoses, the bleed screws and found no evidence of a leak. It appears I'll have to disconnect the hard line at the input on the rear proportioning valve and shoot some air into the hard line from the master cylinder end and see if I have a blockage. If I don't then the only thing I can see is defective is the proportioning valve. Have you removed this valve? Warnings, cautions, suggestions?

[TX82FIAT]

Hope you do not have to replace the lines. Get yourself some flare nut wrenches. Over time the vice grips will wreck the bleed screws.

[SouthwestSpider]

Got the flare nut wrenches but that wasn't good enough. A little heat and ice helped on one line but it looks like vice grips will be the only solution for these things. It's frustrating that buying a single steel brake line (metric fittings) is not possible. I would think that an enterprising parts supplier would put together some lines at about $20 a piece that would enable a guy to repair a single section of a brake line.

[SouthwestSpider]

Fixed it! The center flex brake hose was completely blocked. I replaced it and the compensator hard brake line. All is good!

[TX82FIAT]

That is great news. It is nice when you get the brakes sorted out and the pedal feels like it should and the car stops like it should.