65 C10 brake bleeding issue

[jayoldschool]

Replaced both rear cylinders today. The master had run dry because the left rear cylinder had failed as I was driving home last fall. I topped it up before winter, and the fluid was all the way down before I got to work today. Topped it up again and started to bleed. Got a bit of fluid out of both cylinders. Wasn't making much progress until I asked my helper to push a bit harder, then got a BIG rush of dirty fluid. I could actually hear it going through the rubber line and the T fitting on the axle. Thought I was almost done... until I got no more fluid out. Reservoir is full. Brake pedal is high, and hard. Like I can stand on it with full force and there is only about 2-3" of travel. Nothing comes out when opening the bleeders out back. I've gone back and forth between both. I've left the right rear bleeder cracked to see if it will gravity bleed.

Any ideas what's going on? I haven't felt one like this before (but I've never had manual brakes). The pedal was going right to the floor before filling it up.

Theories:
- I broke something in the master
- there is a chunk of something blocking a line
- the rubber hose over the axle failed on the inside creating a blockage
- aliens

I look forward to your thoughts!

[T and S]

starting at wheel cylinders, work your way back and take apart each union to determine if their is a blockage some where. Its a start.

[60chevyjim]

if you never changed the rear rubber hose , now is the time to do it.
it sounds like it went bad on the inside and clogged up.
you can check by loosening the metal line that comes from the front of the truck to the rear rubber hose . loosen it up where it goes into the rubber hose at the chassis.

whenever I buy stuff this old or older like I allways do .
I allways start by replacing all the rubber hoses and all the wheel cylinders and the master cylinder .
with the old cars that I build I replace all the metal lines to because
I buy 50's and 60's cars n trucks that have sat unused for a lot of years .

so with your brakes , its better to be safe .
than not knowing if they are going to fail when you need them the most .

this is my friends 65 chassis I that am rebuilding for his 65 truck .

[jayoldschool]

Yes, that's exactly what I'm thinking. I did the front lines, front shoes and hardware, rear shoes and hardware last year. I'll do the line tomorrow and report back. I really think that something came loose when I could hear fluid going through there. I've never heard that before when bleeding...

[Cape Codder]

If you have no pressure to the rear hose try loosening the line at the master and see if it is still locked. The cup in the master might have come apart and jambed the piston.

[jayoldschool]

That's what I think has happened. I left the bleeder open, cap off for 24 hours. No fluid came out, reservoir is full. I will get back at it tomorrow, starting with the line on the master, then the rear line. We just got a sweet hydraulic flaring tool at the shop... so I may just do all new lines. If I'm doing that... may as well do a dual master...lol