[mr48chev]

What is the line connected to" You should be able to blow air through a line from the master cylinder to the wheel cylinder if you have the bleeder screw open on the wheel cylinder.

Check the lines inch by inch for kinks or smashed spots. Or being twisted near a fitting.

I haven't seen it on brake lines that I remember but it is real common for guys to twist a fuel line in a knot next to a carburetor and not notice it and then wonder why it won't run. That means check next to any T fitting like on the axle or other fittings.

If you didn't have the line apart that is not flowing you might take the fittings apart and see if it had the farmer fix with a brass rivet stuck in the line to block it off to keep that wheel cylinder from leaking. I've seen it a few times on old trucks and cars we drug in and did it my self on the side or the road 25 years ago when I blew a wheel cylinder and needed to get the truck back to the shop so I could rebuild the brakes. I was braver then than I am now.

You might blow though individual pieces one at a time to see if you have a restriction before hooking everything back together.