Brake Flush issues

[bugsy]

Decided to do a brake flush on our 70Z that we own for 16 years. I removed the old fluid out of the master cylinder which was dark in color. I hooked the Matco mighty vac up to r/r bleeder valve. Hardly anything came out of both left and right rear bleeder valves. Front ones I got fluid out. So now I try and manual bleed them. Put my wife in the car, and I got some fluid out of both rear bleeder valves. Tried it again I got nothing. Seems like brakes apply , but not all the time. Fronts are good. This is a 33k survivor car and I am trying to figure out if its the wheel cylinders. Anybody have these issues. Bleeder valves are not clogged. Still has original blue caps on front bleeder valves. Any help would be greatly appreciated. Thank you.

[ronzz572]

I suggest to turn the key on check if the brake warning light is on. You may have tripped the proportion valve shutting fluid off to the rear. If so it could be a bit of a pain to get reset. You may have to open a front bleeder push the pedal to the till you see the dash light go out or here a click noise centering the valve. Then try bleeding again without heavy foot pressure. Or try your vacuum bleeder.

[bugsy]

Thank you Ron. That's why I like this site. People willing to help others. God Bless all and stay safe Friends.

[ssl78]

Make sure the rubber hose going to the rear brake lines isnt plugged very common

[ronzz572]

Originally Posted by ssl78

Make sure the rubber hose going to the rear brake lines isnt plugged very common

Agree 100% if the brake warning light isn't on. That might be the answer. I have a 70 z28 in my shop now with 95k miles on it. Brakes wont bleed. All the hoses are plugged up. It's been sitting since 1986. Common problem. Brake hoses deteriorate from the inside and clog up.

[Mr.Nickey Nova]

It's just a matter of time that the fronts will do the same thing. Better off changing both front rubber lines and the one rear, then bleed the system again. Should be fine when done...

[Charley Lillard]

On a funny note. The 1100 mile 70Z that I had still has perfect brakes and the lid has never been off the master cylinder since the car was assembled.

[bugsy]

Disconnected the rear hose, it's the original one. Looks like brand new. Tried to run a wire through it and would not go through. Going to try and free up what's inside if I can. Ordered one from napa. Thanks SYC

[bugsy]

Replaced rear hose
Still dont get much fluid from the rear bleeders. I pushed the pin in on the regulator valve. Now the red brake light comes on. Asking before I start taking the braking system apart. Do I have a bad reg valve or combination valve? Looking for some advice before I take something apart that doesn't need to be apart. I believe reg pin is pushed in and did not return. Thank you guys

[ronzz572]

I would continue with more with brake bleeding before anything else. If the brakes worked ok prior to your flush efforts, everything should work ok yet. Loosen both front bleeders and push the pedal to the floor. It should possibly push the valve back the other direction and center it. Try it few times and then continue bleeding the rear, then finish with the front.