Whether you've just installed a set of new brake lines or worked on your brake system in a way that required you to disconnect any of your brake lines, it is absolutely necessary that you bleed your brakes before you drive your Jeep JK Wrangler. Failure to do so will result in poor to non-existent braking due to air bubbles that can get trapped inside your brake lines. Symptoms of air bubbles trapped in your braking system include an excessively soft brake pedal or a pedal that goes clear to the floor without any resistance. If you have any of these symptoms even though you have not worked on your brakes, check for leaks, fix where necessary and then use this write-up to help you bleed your brakes.
What You Will Need
• DOT3 Brake Fluid
• 11mm Wrench
• Brake Bleeding Kit or 1/8" Vinyl Hose & Jar
• A friend to help
1. Make sure you have everything you need before getting started, park your Jeep JK Wrangler on a level surface, apply your emergency brake and put your transmission in park or in gear if you have a 6-speed.
2. If you worked on your master cylinder or disconnected multiple brake lines for whatever reason, you will need to start this job from the passenger side rear brake. If you just worked on your front brake lines, then you need to start at your passenger side front brake. The idea is that you just need to start from the brake that is farthest from the master cylinder.
3. Remove the rubber cap attached to the brake caliper bleeder valve as shown in this pic.
4. Place your 11mm wrench on the brake caliper bleeder valve/nipple and then insert the tapered fitting into it as shown in this pic (or over the nipple if you have a hose that will fit it). Attach the jar using the magnetic head anywhere below the nipple.
5. Have a friend sit in the driver seat with the engine off and then, on your command, have them push down on the brake pedal slowly to the floor.
6. While your friend is holding the brake pedal down, slowly loosen the brake caliper bleeder valve so that the fluid inside flushes out. You should be able to see the fluid and air bubbles moving through the clear vinyl hose in a burst. Once the flow stops moving, tighten the bleeder valve to close it off. Instruct your friend to release the brake pedal and repeat this process as many times as is needed until you see no more bubbles coming out.
7. Reinstall the rubber cap, check the fluid level in your master cylinder and refill as necessary. Repeat the process on the driver side rear brake, passenger side front brake and last but not least, on the driver side front brake. It is very important to NOT let your master cylinder run dry during this process.
After you've bled all 4 brakes, give your master cylinder one last check and top it off if needed. Your brake pedal should now feel nice and firm.