WJ Swap-Trouble Getting Fluid into Lines

[Super mud]

So I got a 91 comanche that I just redid the system to where the front and rear split. It had a load sensing proportioning valve that I trashed and now has just a single line for the rear with an adj. prop valve and the front line from the master just runs to a Tee. I did the WJ booster and master since the old replacement already leaks. Now my problem is I can't get fluid from the master to even start to enter the line. I've tried pumping the master, pressurizing the reservoir, vacuuming at the bleeders, reverse bleeding at the bleeders and still nothing. At first I didn't bench bleed master, planning the reverse bleed would take car of it. Then later bench bled it and tried everything again. The only time the fluid level ever went down was when bench bleeding it. I've done a full rebuild on my xj where I bled the master and started with a dry system but have no idea whats wrong with the mj. Thanks.

 

[Devilfrog]

OK, I'll take a stab at this ...

First can you post a picture of your master/prop valve arrangement?

Now, from the master you should be going into a proportioning valve which splits the circuits from front and Rear, to Left/Right Front and rear. then the lines will be individual to each front caliper. At the rear you've deleted the load sensing valve si you should just have a simple Tee there. If you added an adjustable prop valve it should be placed off the master betwwen the front/Rear circuits. It sounds like you have it as the Tee.

You've bench bled the master so then you'll ned to move down the lines bleeding as you go ... Master, Prop valve, then on to each caliper ... if your lines are full of air you may get an air lock preventing it from gravity bleeding.
I would start again with the Master then check for fluid at each fitting downstream from there.

 

[Andy in Pa.]

It doesn't sound like the master was bench bled enough, or properly. New master cylinders come with a kit for bench bleeding. Did you use this kit or something similar? Did you run the outgoing lines coming out of the master into the brake fluid reservoir? Did you make sure the lines were submersed in brake fluid? When bench bleeding, it moves fluid BOTH ways, so the other end of the lines need to be submersed in brake fluid so they can draw some back in.

 

[Tacedaddy]

first time i swapped in a WJ mater cyl i screwed up one of the double flares took me 4 hours to figure that one out

 

[Super mud]

I only have one line running to the rear, straight from the mc with the p valve inline.

What I found out is that the wj mc seals from the resovoir as soon as pressure is applied using 2 single plungers instead of 4 like the diagrams I've seen. So once I allowed the mc to relax, it gravity drains fine. Figured my rod length was too long and disconnected the pedal but with everything sitting like it came out of the wj, the mc is preloaded 3/16 of an inch. This is still sealing off the resovoir. Wtf and the rod in the booster is not adjustable like the older models. It dosn't make any sense and I've read the systems on other cars shouldn't be pushed together either.

 

[Tacedaddy]

you should not have to adjust it my friend. You may just have a defective master or its not bled properly

 

[Super mud]

you should not have to adjust it my friend. You may just have a defective master or its not bled properly

I tried a second master, same scenario. So I drilled the mc shaft deeper to make up for the length and it bled like a champ. Didn't even bench bleed it. Just reverse bled the system and bled air out the mc fittings. Done.

I don't know what the correct setup for the booster/mc combo out of the wj is supposed to be but this is allowing the mc to work like it's designed as far as I can tell.