Brake pedal goes to the floor

[Cheyenne1010]

I have a 1973 chevy C10,I've installed new front brake pads,new front brake calibers,new front brake lines,new brake master cylinder,new brake power booster,new rear brake cylinders and I've bled all the old brake fluid out so it has new brake fluid throughout the whole system.when I first start the truck after its warmed up,I press the brake pedal and it Almost goes to the floor.if I pump the brake pedal a couple of times it'll get firm.so now I'm driving down the road and when I go to press down on the brake pedal it goes to the floor.I've bled the brakes starting with passenger rear,driver rear,passenger front then driver front.I've also tried bleeding them with a mighty vac pump and a pump that pushes brake fluid from each wheel back to master cylinder.could the problem I'm having of not achieving a firm brake pedal be caused by the proportioning valve?there's one end of that valve that I believe is soppose to be partially sticking out and its not,it looks like it was pressed in.the proportioning valve is the only part I have not changed.any help will be appreciated
   Thanks guys..

[1967KaiserM715]

Did you bench bleed the master?, sounds like there is still an air pocket, or a leak someplace.

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[Cheyenne1010]

I did bench bleed the master cylinder,and there are no leaks.i even exchanged the new master cylinder for another new one in case the first one was defective.

[1967KaiserM715]

This may be a little hard, but a couple good stomps in a "panic" stop should reset the valve. But I don't see that as a source for a soft pedal that gets firm after pumping. Dead end/dirt road, away from civilization for safety reasons.

Typically with vacuum boost brakes (vacuum assist, or are they manual or hydro-boost?) A pedal will typocally get easier to push if the vacuum is leaking, but you could get that tested, any good auto shop can smoke test.

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[Irish_Alley]

whenever i having a big problem with bleeding ill gravity bleed them. ill crack the valves and walk away eat or something and come back tighten them up and its normally good to go

[Cheyenne1010]

1967kaiserM715 the power booster is vacuum and is brand new

[Cheyenne1010]

Irish_Alley when you gravity bleed do you take off the master cylinder cap off?

[Irish_Alley]

i did so i can keep an eye on the fluid level every so often. also if you dont it might do the whole "finger over the straw" and not let any fluid out

[Cheyenne1010]

One more question,did you crack open all four valves at once or one at a time?

[Irish_Alley]

I would do one at a time. Not sure if you could do all 4 don't really see why not but I didn't want to empty the brake cylinder

[VileZambonie]

If you bench bled the mc and got all of the air out and bled all of the lines as you say then go back and recheck your brakes. Did you adjust the shoes?

[Cheyenne1010]

I adjusted the shoes to the point where they were touching the drums.how hard or easy is it to bleed air out of the proportioning/combination valve?about a month ago I had to remove the steering box so I had to remove the two brake lines from the proportioning/combination valve and I'm sure air got into it.the proportioning/combination valve is the only part that I have not changed.

[VileZambonie]

You bleed it by the bleeders at the wheel cylinders and the brake calipers. Recheck your adjustment on the rear brakes.

[Cheyenne1010]

I've recheck the adjustment in the rear shoes and its good.I'm just going to start over with bleeding the master cylinder then bleed each wheel and see what happens.that proportioning valve button on the side is still pushed in and I'm pretty sure that it needs to be set to the out position.