Brake bleeding 101

[92xjlaredo]

also on a more serious note...i once had to plug off the rear brake line directly at the master cylinder when my frame broke to get the jeep home (as it ripped my lines right off of the wheel cylinders) perhaps someone has done that or possibly the splitter is plugged or ruined? proportioning valve messed up possibly?

[DizzDizz]

Maybe a crushed or blocked brake line?

No then you wouldnt have a weak pedal, it would feel normal just no function of the rear brakes. I have seen this before where the master cylinder had been leaking fluid into itaelf. Crawl under your dash and look where the rod goes through to see if any fluid or signs of fluid leaking into the cab. Or your poportioning valve could be fucked up. Im gonna bet the master.

[HeavyMetal]

i guess my tiny brake bleeding brain cant make sense of the fact that the fronts would bleed 100% normal and the back not at all if it was the master cylinder

[CumminsJeep]

What dizzy said. If you have a kinked or collapsed line you would still have a firm pedal but just no brakes. or it would feel like they are sticking on if some fluid is going through but just not returning fast. If you aren't getting any fluid to the rear it could possibly be a master or a proportioning valve is stuck. If the pedal slowly sinks to the floor i would say its either the master or the booster. I would doubt that it is a collapsed line, it sounds like another issue.

[HeavyMetal]

i think i will give the master a try today, thanks guys

[justtorchit]

Just throwing another idea out there..... I had an issue with bleeding brakes on the toyota we built. The master is a chevy truck master....
well I was trying to bleed the brakes for fuckin hours, could not figure out what the hell was going on. i would crack the bleeders have someone pump and fluid would not come out. no pressure would build up. After about 3 hours of mind fucking myself i made a phone call to justin lawhead and was informed to just FUCKING STAB THE PEDAL AS HARD AS I COULD.... im like yeh right, ive been pushing the damn thing for 3 hours...... well 1 good chuck norris kick to the pedal later i was bleeding the brakes without an issue.... some sorta valve or pin in the master needed to be set and i guess thats how ya do it....

not sure if the jeep masters have the same thing. but give it a try if all else fails. sounds like the same issue i had trying to get the rear brakes to bleed.

[HeavyMetal]

bought new master, bench bled it, swapped it in, identical problem. removed bleeder screw entirely, no fluid exits. inspected line, doesnt appear to be fucked in any way.

this is going to go to a local garage to anally rape me at this point...cant waste work days fiddlefucking around with guessing.

[Hydra]

Why don't you just come get that line from me... btw is this abs?

[HeavyMetal]

abs yes

[Buffalo Phil]

HAS TO BE ABS.

[Hydra]

I don't know how the XJ abs works, but I feel that could do it

[Ruepart Hoaxley]

pull ABS unit, run lines like non-ABS XJ would have, pull ABS fuse, call it a day.

[customcreationsllc]

I've had that happen too many times.

The combination/proportioning valve has a shuttle valve for when you loose a brake line front or rear the valve shuttles over stopping any more fluid.

I bet your brake line is on!
the switch on the top of the Combo valve turns on when the valve shuttles over, so the driver knows when they loose a brake line.

When there is equal pressure on both sides the shuttle valves stays in the middle.

It gets stuck and can be a a royal pain to reset. I've always eventually got it to bleed.
Try bleeding the rears with the fronts open, it equals out the pressure.

Always verify you have brake pressure coming out of a master by cracking the line at the master the front line should be for the rear brakes.

if it was a leaking line you would see a puddle.
I've never got a crimped line to stop brake fluid. I've tried vise grips with no luck so I highly doubt it is a crimped line. Dragging brakes I would agree.

abs shouldn't matter for bleeding

Good luck

[HeavyMetal]

Try bleeding the rears with the fronts open, it equals out the pressure.

I just did this (didnt proper bleed, just verified if i got flow) and it got fluid out the rear bleeder. i closed the fronts back up after a little pumping, and then nothing comes out the rears again

its too dark now but i can revisit it tomorrow maybe. ran out of fluid either way

[customcreationsllc]

you can try reverse bleeding it by pumping fluid into the bleeders and out the master.
A pain but actually the best way to bleed.
And that should reset the valve.

I know it is a pain I've gone through plenty of bottles bleeding before.