1. #1
    Postofficemike's Avatar
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    Red face Brake Booster for 89 YJ Wrangler

    Do I need to replace the brake booster if, when I press the brake pedal, it goes almost to the floor, but if I pump it 3 or 4 times it builds up? Not good for a quick stop if someone pulls out in front of me.

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    Re: Brake Booster for 89 YJ Wrangler

    That is normally a sign of air in the brake lines. Try bleeding your breaks and see if that helps.
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    Re: Brake Booster for 89 YJ Wrangler

    I agree with Terry. Try bleeding the brakes.
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    Re: Brake Booster for 89 YJ Wrangler

    I did try to bleed the brakes, but it didn't help. Would the booster be the next thing to replace? Is there a way to test the booster? Also, has anyone used the "Speed Bleeders" for bleeding the brakes? It looks too good to be true.

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    Re: Brake Booster for 89 YJ Wrangler

    usually, a booster being bad will make a hard pedal or your idle will raise when you push the brake pedal. a spongy pedal is normally air in the brake lines, especially with your description

    google testing a brake booster and it will pop up exactly how to test yours.

    are you asking about the speed bleeder little things that go on your calipers? i have on my bmw. they worked fine for me
    no more jeeps at this time. next time it will be a cj with a v8

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    Re: Brake Booster for 89 YJ Wrangler

    I agree with the air in the lines but, also if rear brakes are way out of adjustment the pedal will pump up after the wheel cylinder pistons push out far enough for the shoes to contact the drums.

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    Re: Brake Booster for 89 YJ Wrangler

    You could also have a small leak somewhere in the system. My rear drums had a small leak, and it really affected my braking performance, as the pressure would "escape" through the leak. If you DO decide to change the booster, I would recommend trying to make the 95.5 model fit (you'll need the master as well), as it is a double diaphragm design, but, to be honest, I doubt this is your issue. And if tried bleeding, try raising the front of the Jeep and turning the wheel from one side to the other with the Jeep off a couple of times; sometimes bubbles get trapped and are hard to get out.

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    Re: Brake Booster for 89 YJ Wrangler

    My suggestion would be to park on some clean concrete and pump your brakes for a while, then crawl under your Jeep and look at each wheel's brakes for fluid. You may need to come back the next morning and look again.

    Do you need to add fluid in your master cylinder periodically?
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    Re: Brake Booster for 89 YJ Wrangler

    Quote Originally Posted by TerryMason View Post
    My suggestion would be to park on some clean concrete and pump your brakes for a while, then crawl under your Jeep and look at each wheel's brakes for fluid. You may need to come back the next morning and look again.

    Do you need to add fluid in your master cylinder periodically?
    No. That is what is confusing. There is no drop in fluid level. No wet spots around any of the bleeder valves. No leaks from fittings. What I noticed today is that if I pump the brakes I can hear an air sound from under the brake pedal area. Do you think some part of the booster is leaking from the back? Thanks.

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    Re: Brake Booster for 89 YJ Wrangler

    I hate to show my limited knowledge, but you guys seem to know your stuff and I guess I'll not learn unless I ask. Do I have to jack up the Jeep to bleed the brakes? I can get under because of the height, easily. Thanks.

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    Re: Brake Booster for 89 YJ Wrangler

    the air is normal because the booster runs off vacuum. it should make that noise.

    you should be able to lay right in front of or right behind each wheel and reach the bleeder screw with no jack.
    no more jeeps at this time. next time it will be a cj with a v8

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    Re: Brake Booster for 89 YJ Wrangler

    Thanks a lot for all the advice. Will try these things tomorrow and will post which one it was.

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    Re: Brake Booster for 89 YJ Wrangler

    i decided to bleed the brakes again and that seems to work this time, so thanks again for all the replies.

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    Re: Brake Booster for 89 YJ Wrangler

    Sometimes you have to drive it with a soft pedal for a while to allow the air to move outwards. I've had the same issue previously and waiting a week and then rebleeding fixed it
    no more jeeps at this time. next time it will be a cj with a v8

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