braking problem

When I'm coming to a stop sign, I can't stop because the brake doesn't work in gear. In order for it to kick in, I have to go to neutrual and even then the brake is loose. I just bought a 91 xj 4.0 with 159100k miles, only 400 bucks...it should be a good project

Sorry to ask for more info, but it would help us help you with a little more information.
If what I understand from your statement is correct, you couldn't drive this thing. Do the brakes not work AT ALL when in gear or are they just so weak that the engine pulling in drive overcomes the brakes? What is "loose" in the brake? Is this an automatic transmission?

winterbeater said:

Sorry to ask for more info, but it would help us help you with a little more information.
If what I understand from your statement is correct, you couldn't drive this thing. Do the brakes not work AT ALL when in gear or are they just so weak that the engine pulling in drive overcomes the brakes? What is "loose" in the brake? Is this an automatic transmission?

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Yes I can drive it, but not safely. The brakes feel as if they work in drive, but they are soo weak it doesn't do anything. Yes it is and auto. And what I mean by "loose" is, I have to push the brake pedal all the way down like there is no pressure.


Thanks for your concern

That doesn't sound like a vacuum booster problem, that'd be a hard pedal.

And if it's affecting all 4 wheels, start with the master cylinder.

morr2010 said:

When I'm coming to a stop sign, I can't stop because the brake doesn't work in gear. In order for it to kick in, I have to go to neutrual and even then the brake is loose. I just bought a 91 xj 4.0 with 159100k miles, only 400 bucks...it should be a good project

Click to expand...

Sound like you have more than one problem.
If braking improves while in neutral, you many have a bad vacuum check valve on the booster.
The rear brakes may need adjusting to bring the pedal up. Who knows what else it bad.
If it were my XJ, I would park it and go through the entire brake system, verifying the condition of each part before driving it again.
If you keep driving it the way it is, expect an accident.

morr2010 said:

When I'm coming to a stop sign, I can't stop because the brake doesn't work in gear. In order for it to kick in, I have to go to neutrual and even then the brake is loose. I just bought a 91 xj 4.0 with 159100k miles, only 400 bucks...it should be a good project

Click to expand...

have you pulled the wheels and looked at the pad/rotors and drums/shoes?

have you bleed the brakes?

do you here any hissing when the braakes are applied?

not building pressure could be a bad master.

i would do a visual check of the brake components, adjust the rear brakes, and then bleed. also check the condition of the fluid and condition of the brake hoses.

If it were my XJ, I would park it and go through the entire brake system, verifying the condition of each part before driving it again.
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X2 First thing
What size tires are you running?
What other mods have you or the PO done if any.
What is your Idling RPM and or are you using and extended idle system.

How is your brake fluid level? You didn't say it was going down. If you pump the pedal 10 times and hold it down hard, does it hold firm or slowly go down to the floor? If you are not losing fluid (from calipers, wheel cylinders, or rotted out brake lines), but pedal goes down, it is a bad master cylinder. In any case, being that this Jeep is new to you, by far the best plan would be to pull off all the wheels and drums to look at the brakes. If rotors are rusty, the calipers are frozen up (rust, dust, etc.). XJ's also have a problem with the rear drum brakes not adjusing up properly. And of course check out brake lining. Metal to metal doesn't stop good.