The Rover-Landers of BC

Looking for some suggestions please,
Returning home from Founders day, my 88 made to the alley way behind my house when one of the rear hard brake lines broke.( missing support bracket)
I repaired the brake line, and tried bleeding the brakes. Wasn’t getting much out of the rear brakes at all. Front brakes bleed fine. Used the pumping / hold/ release nipple method, and the Mity Vac method.
I have a Wilwood dual master cylinder, power brake unit, disc brake conversion on front, standard 10” brakes on back.
Brake pedal also stopping hard half way down.
I ordered a replacement master cylinder, (need one for the 109 anyways,) bench bled it, installed on truck and re bled it using the pedal with hoses going back into the master from the ports. Pedal would go to the floor, no problem at all. Installed brake lines to master, pedal stops hard 1/2 way down again. Front brakes bled fine, still not much going to the back.
Thought maybe something in the rear brake lines, so I disconnected brake line at master and in the back and put air to it in reverse fashion, plenty of air going through, line isn’t plugged , kinked etc.
All I can think, is there is something going on with the 5 way valve on the frame rail right hand side. Do these have a shuttle valve in them? If so, how do you reset them?
Green bible doesn’t seem to have anything on the 5 way valve, other than diagrammatically locating it within the system. Help please?

Check the soft line from the frame to the rear axle. Over time the rubber degrades and can collapse inside the line. I’ve seen it before.

I will check that line Martin, but I thought blowing it out backwards with air might have ruled that out. Heaven knows I have been wrong before!!!

Yes. There is a shuttle valve to stop flow with a failed line. It is probably stuck. Open it up and free the valve.

https://www.autoexpress.co.uk/land-rove ... es-iii?amp

I always had a very difficult time bleeding the brakes on my ‘63 88” (single master cylinder) until I used a bit of air pressure on top of the reservoir. I dialed my compressor down to about 8 psi and used a rubber hose to sort of seal the pressure on the vent on the reservoir cap, with one bleeder open at a time. Really a gravity bleed with some extra help. This worked quickly every time for me.