Brake Issue

[mmsidaho]

I'm looking for some advice on a brake issue I've got on a 72 C20. It's got stock power brakes with Delco Moraine parts.

With the transmission in drive, the brake pedal goes all the way to the floor and there is no braking. When I put it in neutral, I'm able to pump the brakes up to at least get the truck stopped (not normal, but at least partially working).

I pulled a wheel last night just to check what the front pad wear was like and they look almost new still, so it shouldn't be a pad issue.

I also checked the brake fluid level in the master cylinder and it was good. Does this sound like either a master cylinder or booster issue?

[Longhorn 70]

sounds like master cylinder to me. have you tried bleeding to see if fluid actually comes out of any of the 4 corners?

[mmsidaho]

I haven't tried that, but up until a couple of days ago they were working fine and where the master cylinder was still full and there were no signs of fluid on the ground, I wasn't thinking it was a fluid related issue.

Are you suggesting removing a hose at the caliper and then pumping the brakes a bit to see what comes out?

[GASoline71]

Just loosen the bleeder screw at the caliper or the drum and see what comes out.

Gary

[ole dollor]

your old master cylinder may be bypassing fluid internally , first like others said try bleeding the brakes, then go from there. it does sound like m/c...you can adjust the rear brakes to get a better peddle once you get the brakes working properly again...

[mmsidaho]

Thanks for all the advice. I'll try bleeding first and then, most likely end up replacing the master cylinder. Should I check (bleed) all four wheels or is one enough? If I either get fluid coming out or don't, what is that telling me?

[ole dollor]

all four need to be bled.