Problem bleeding brakes

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Demon 408

Demon 408

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The system includes all new brakes parts: calipers, wheel cylinders, lines and proportioning valve. Brakes are all maunal (no booster), front brakes are 73-76 A Body disc with 10" rear drum. Calipers are mounted in front with bleeder at the top (stock location). The proportioning valve is from Inline Tube (part number BLK250). The master is a newer Mopar style that I bought from Rick E'berg, it's a cast iron model with plastic body and two separate plastic caps. I reused the factory manual brake rod that was on the car. I'm guessing it is/was correct for a manual drum brake car. I'm using Valvoline synthetic DOT 3/4 fluid.​

Bench bled the master cylinder. I bled it until the there was no air bubbles in the clear plastic lines. I re-bled the master on the car, it looked good. After that I conected the hard lines. I have not allowed the master to run dry at any time. I bled the front brakes and got a "rock hard" pedal at about the 1/2 way point on the pedal travel. ​

I tried bleeding the rear brakes and there was no fluild flow to the rear wheel cylinders. So I removed the brake line at the rear end connection. The pedal stayed firm with line removed, and still no fluid flow. So I connected the bleeder bottle directly to the front of the master cylinder and got fluid flow. ​

So that leaves the long line from the front to the back of the car, but it's new and I didn't find any kinks, and lastly the proportioning valve. I read my FSM and it said that on cars with vertically installed proportioning valves you need to "fool" the valve to make it act like the front has a leak so the valve will switch and you can bleed the rear. I opened the front and rear bleeders on the right side of the car. The front bled fine, but again no fluid flow to the rear.​

I don't think the rod is a problem because I'm able to pump fluid through the master when I had the front master line (rear bakes) emptying into a bottle.​

Ideas?​
 
just a thought, with both ends of the long front to back line disconnected, can you blow air through it? Or is it possible a piece of something got stuck in the proportioning valve?
 
make sure you have fluid coming from the proportioning valve where the rear line threads in, which you probably will, it sounds like you might have a piece of dirt that made its way into the opening of the main front to rear line when installing it, unhook on both sides and try compressed air to see if it will blow freely through, do the same for the lines that run across the rear axle, I usually put electrical tape over the ends of the line before installing them to ensure dirt stays out of them
 
You'r pro valve has the rear locked out, as you probably pushed the pedal to the floor while bleeding the front. Crack a front bleeder, and SLOWLY push the pedal; about halfway, you will feel a click. Stop, and tighten the bleeder; you just re-centered the valve. Now, bleed the rear. Never push the pedal more than halfway, or the click.
 
green1 said:
You'r pro valve has the rear locked out, as you probably pushed the pedal to the floor while bleeding the front. Crack a front bleeder, and SLOWLY push the pedal; about halfway, you will feel a click. Stop, and tighten the bleeder; you just re-centered the valve. Now, bleed the rear. Never push the pedal more than halfway, or the click.
Click to expand...

That makes sense. Did you learn this from personal experience?

I tried to get the valve to center but I had both back and front bleeders open. I'll try your method in the morning. Thanks.
 
Finally got it done. There was a lot of air in the lines that was causing the problem. Man did it take a lot of pump, hold, and bleed before the rear brakes worked. The first round I tightened up the rear brakes and got them to bleed a little. So I loosened the rear brakes up and bled them again. Got a really rock hard pedal at about the 1 to 1.5 inch from the top of the pedal travel.

Did I mention how much I hate bleeding brakes...
 
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