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Brake Issues


NAXJA Forum User
Ok, so I recently bought a 1989 Jeep Cherokee Larado have been tinkering on it. But the issue I have run into is my brakes. So far, I have replaced the front calipers and pads and have put new shoes on the rear. I also put in a new master cylinder.
But every time I press on the brakes, the pedal goes all the way to the floor. If I pump it a few times, it builds up pressure, and I can stop. I have bled the lines 5 times now and have not been getting any air out of them. My cruise control and vent controls don't work either (it only blows air through the defrost vent), so I think it might be a vacuum issue. I am currently pulling 10 inches of vacuum, and I think I should be in the 12-14 range. I also wonder if it might have something to do with the brake booster, but I don't really know.
Any help would be greatly appreciated.
I can't help much, but vent controls and cruise definitely point to a vacuum issue. You might check for vacuum leaks first.
If your booster goes, most often the pedal gets really hard to push, it doesn't go all the way to the floor.
The air tends to rise in a fluid. Might be air in the master cylinder. The best course IMO is to pay to have the brakes power bled. I've had issues in the past with getting a master cylinder properly bled. It can be a crapshoot. If you have ABS it is a whole other can of worms.
Whatever you do don't let the reservoir go empty or all your effort is for nothing and you'll have to start all over again.
It is also possible to have the rears so far out of adjustment you lose pedal height. Pull the parking brake, back slowly and brake, repeat a half dozen times. This helps the auto adjuster work. A large parking lot is good for this. Make sure your auto adjust lever in the rear is installed properly (easy to screw it up) and the star wheel turns freely. The star wheels are left and right mixing them up is bad.
Your vacuum issues sound like the vacuum reservoir behind the front bumper passengers side. Or a rotted vacuum line under the battery. The vacuum reservoir (the football) is prone for the mounting tabs breaking off or the vacuum line popping off or both. I use large zip ties to hold mine in place. Without the reservoir, a common symptom is windshield vent only at low speeds.
Might be air in the master cylinder.

That's what I was thinking. With your vehicle off, the brakes should feel very tight and not go all the way to the floor. Once you turn it on, the pedal should feel softer. That means the booster is working.

Search youtube for XJ master cylinder bleed vids.
completely replace the fluid and make sure you get a good bleed. sounds like air in system