No fluid to rear brakes

[427]

I have a 68 f-100 that's been sitting for about four years in my garage. The master cylinder was dry and I filled it but no luck on building pressure. I then put 4 new wheel cylinders on it. Installed new master cylinder and front brake hoses. Once again I have no pedal. I then take the master cylinder back and exchange for another one. At this point I now have solid pedal and front brakes. I don't have any fluid at rear brakes. Now frustrated I take it to the local mechanic who tells me there is no fluid at the distribution block on the frame coming out to the rear. He is trying to convince me into Disc brakes which he quotes me at $1500. I just want my brakes that I have to work because they always stopped me before. If this is so where can I get a new distribution block or can I use another type such as a proportional valve. I know disc brakes are best but id rather fix what I have and use the $1500 elsewhere on my truck. Thanks for any ideas.

[Ranchero50]

Brake are pretty simple if you break them down and treat them like the plumbing that they are. Loosen the line at the master cylinder and bleed it until you have fluid there. Tighten that fitting and move to the distribution block and verify the line is flowing fluid. Do that same at the distribution block and finally at the wheel cylinders.

On my F-350 the distribution block plunger was frozen and took some time to get out and apart to free up the plunger. PITA because it was tucked into the frame on the F350, not under the master cylinder like some others. When you lose brakes the plunger shift in that direction to block the flow of any more fluid so the pedal stays firm.

Sounds like your mechanic is already saying that the distribution block plunger is in the blocking position. On newer stuff the plunger will reset if you release pressure on the front brakes and have good pressure on the back brakes to the distribution block. My truck needed manually reset.

[427]

Thanks for the help Ranchero50. That makes sense about the valve shifting to maintain pedal. Is there a rebuild kit for the junction block? How do you reset the valve inside? I would bet even though my truck was sitting when the fluid run out the valve did its job and consequently became stuck.

[Busboy]

I'm gonna have to chime in here. The distribution blocks pressure differential piston is there only to ground the terminal on the brake warning light when there is a significant difference in pressure between the front and rear hydraulic systems. It doesn't "block off" the side with the leak. From my experience the Ford distribution blocks have to be manually reset by removing the switch and centering the valve. GMs can be "hydraulically" reset by opening a bleeder screw on the "good" side.

[ultraranger]

Ford instructions for recentering the pressure differential valve.

[427]

Thanks for all the great info. I have learned what is in that valve. I never knew it was a safety also. I think the re setting part is why I have no fluid at the rear.