88 Comanche pioneer long bed rear brake dilemma

[Comanche man Don]

Ok guys, what is the best route in dealing with that height proportioning valve on my rear brakes. It nasty it’s rusty and i don’t know that it even works anymore like it should. I have a suspicion that it might be clogged. Does that ever happen? I say that because when I bleed the rear brakes the brake fluid doesn’t gush out but rather spurts out. However when messing with the arm on the valve I got the fluid to bleed out better but still not like it should. Either way I’m doing some brake work back there and it’s time to address this valve. Can it be rebuilt? I know buying a new or used one is never going to happen. So if it can’t be Rebuilt what are my options. Is there a practical way to bypass it?  Any input is appreciated.

[Dzimm]

It can be easily bypassed.  Remove the valve and lines around it.  You'll keep the softline and the main line that comes in down the frame rail and tie them together at the fitting that's mounted to the frame.  The secondary line will need removed and capped back at the distribution block, or replace it with an XJ distribution block.  Also would be a good time to do the dual diaphragm booster upgrade as well.

[MiNi Beast]

  

[Comanche man Don]

So to clarify your saying that I only need the one line that runs along the frame and the other line on the frame can be terminated?also I cap it in the block that is attached to the frame there towards the rear?

[Comanche man Don]

If anyone has some pictures of this done it would be very useful

[silvertwinkiehobo]

Before you ditch it, does the arm actually move? I'd think that if it does, the valve can actually work. The trick in bleeding the rears is to put a load in the bed, then bleed them. Of course, do the rear bleeding, then do the fronts, but have the valve hooked up, load the bed with weight (Maveric's boys and myself sat on the tailgate while he and Mrs. Maveric did the bleeding), then run through the complete bleed sequence.

[Comanche man Don]

I have “simulated” a load by moving the arm Up and yes it does move. It’s very easy too move maybe to easy??do they clog? I feel like brake fluid should gush out when I’m bleeding the brakes. Upon further inspection I’ve discovered that the fronts also have a weak flow when bleeding them. I have a new master cylinder that was bench bled and a new booster. Also I have replaced calipers and wheel cylinders. This is why I think maybe there is a blockage or something. Does the proportioning valve coming off the master cylinder ever get blocked?. Or maybe the block that ties into the rear brakes blocked ??my  issue is not that my brakes are grabbing to much but rather that they don’t grab enough and my brake peddle is very soft. I’ve bled it a hundred times and best I can tell there is no air in the lines. Just very weak flow.

[fiatslug87]

In order to bleed MJ brakes:

Open the right front bleeder

Depress brake pedal and hold

Start engine, brake light should stay on after engine starts indicating bypass valve has moved (sensed front brake leak)

Turn off engine, leave bleeder open, release parking brake

Bleed left rear 

Bleed right rear

Bleed righ front (close bleeder when done)

Bleed left front

 

This is from the FSM (an accurate one)