Need help--Brake pedal goes all the way to floor after several new parts replaced Options

[914xr75]

I posted a few weeks ago about leaking reservoir tubes under the gas tank. I replaced those and the leaking stopped. I bled the calipers, but did not bleed the master cylinder. This was the first time I had about 5% stopping power and the pedal went to the floor, not sure if you'd call it spongy, but there was no resistance. That was a couple weeks ago.

Today I replaced the master with a 17mm ATE, rebuilt one of the front calipers, replaced the front soft lines. The rear steel lines still looked good, so I left them. I bled the new master. It took about an hour of pushing out air bubbles, and two quarts of brake fluid into the system to complete the MC bleeding. Once done, the pedal was still pillow soft.

Now on to the caliper bleeding--I purchased the Motive pressure bleeding system. Pumped it up to 5 psi as recommended by Ian Karr. About 30 seconds later the Motive bottle was at 0 psi. There aren't any fluid leaks in the brake system. I replaced the reservoir seal and added Teflon tape to the fitting in the Motive hose. Still loses pressure.

I tried the HF bleeder you hook up to your compressor. For 3 minutes about 5% fluid and 95% air entered the bottle. About 8 ounces of fluid came out. That is where I left off after a full day of brake work. Then I thought, did I cross the reservoir lines? I don't believe I did that, and I don't think that would cause my situation.

Any help you can offer would be greatly appreciated. Sean

[davep]

Your profile does not list a 914, so that does not help.
Normally, when bleeding brake system, you start bleeding at the furthest point which is the right rear, then the left rear, right front and finally the left front.
While I do use a vacuum bleeder tool to do initial bleeding, I always use the foot on the pedal method (two people) to do a final bleed. The foot on pedal method can build the pressure to a much higher level that squashes the bubbles much smaller to get through the pressure regulator and the calipers. Also provides great feedback as to how the system is clearing up.
If fluid is disappearing, then check under the master cylinder, and in the pedal cluster.

BTW, I almost always drain the calipers of all fluid first; just to get rid of all the old fluid. I have rebuilt a lot of calipers since 1975, and the outer pistons are often full of sludge because ordinary bleeding does not force a fluid exchange in the outer caliper halves. Particularly in the rear calipers with the adjusting mechanism in the pistons, no fresh fluid can displace the old fluid with a normal bleeding process.