[KyleSeal]

Hello all.

Im working on a 78 GMC C25 (2WD) front brakes.

The issue started when the customer described to me that the front left felt 'grabby' at higher speeds. The red brake light on dash was on.

By grabby, what we are saying is that it felt like an ABS issue on a modern vehicle, and like the brakes were off-on-off randomly, causing a front left nose dive. I suggested doing pads, rotors, calipers on the front as the old stuff was crusty, and rotors had heavy grooves. Taking apart, found that the front left caliper was leaking from the piston at some point, possibly active. My guess was that this was causing the red brake light, as in the prop valve had been triggered (possibly causing this 'grabby' issue?).

So I proceeded, checked hose flow - good. Replaced pads & rotors + calipers with some off the shelf units. Reset prop valve with the bleeder tool I had, red brake light on dash is now off BUT the brakes are non-existent.

When I bleed the brakes, I am getting a ton of air, and I mean a ton. I feel like Ive run two quarts through the front brake lines and still, air, and lots of it. I even replaced the bleeders with Speed-Bleeders so I wouldn
t have to bother anyone to bleed with me. I did notice the bleeder on the passenger side was loose at about 1/8th turn, and putting fluid out, possibly pulling air in between pedal strokes?

I have checked, no leaks, lines are in good shape, all connections are dry, prop valve tool is in when bleeding, calipers are bleeder @ top, and I have no idea where to proceed from here.

What gets me the worst here, is that before this I felt like the pedal was reasonably good, small bit of dead-travel, but honestly better than most I've driven. But now the pedal is just zero resistance.

Is it possible whoever drove this before I got to working on it ran the master dry and killed it? Im at a bit of a dead end of my expertise with this issue.

Thank you for any help.