MAINTENANCE : Bleeding the Brakes on a Jeep JK Wrangler

wayoflife

Administrator
Staff member
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
• Rags
• A friend to help

Instructions
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.
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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.
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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.
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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.
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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.
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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.
 

kaptkrappy

New member
Great write up.

I like to put the box end of the wrench on the bleeder instead of the open end and then slip the rubber tubing on the nipple.

The flats for the wrench on brake bleeders strip so easy I think they make then out of bubble gum.

.
 

69mach1

New member
Great write up.

I like to put the box end of the wrench on the bleeder instead of the open end and then slip the rubber tubing on the nipple.

The flats for the wrench on brake bleeders strip so easy I think they make then out of bubble gum.

.

Good write up, good tip on the box end wrench so you don't strip the bleed valve and be sure to top up the master cylinder reservoir before bleeding the system . Some folks are having a soft brake pedal after installing braided brake lines. They simply disconnect the brake lines and let brake fluid drain out while they are putting on the new braided lines. The problem is a lot of air is getting into the brake system hard lines and anti lock unit. When that happens you need a special service module/computer to open and close valves in the antilock unit while bleeding the system. I've found a way to avoid this:twocents: It takes two people to complete, one to put a finger on the disconnected brake line and hold it, the other to do the replacement work. Once you disconnect the upper brake line connection have your buddy put a finger over the hard line fitting so no brake fluid leaks out, which also means no air will get into the brake system(antilock unit). Now loosen the bleeder valve on the caliper, loosen the lower banjo bolt attaching the brake line to the caliper, remove and install the new braided line complete with new copper washers. Before connecting the top brake line fitting take a small syringe (I use a WD40 red tube connected to the syringe) filled with brake fluid and slowly fill the new braided brake line from the top. Eventually brake fluid will start coming out of the bleeder valve once the caliper and brake line are full of brake fluid and almost no air. Tighten the bleeder valve. Now quickly make the top connection of the braided brake line to the hard line of the JK. Once this is tight complete Eddie's brake bleeding procedure and you should be good to go :brows:

Now you can install braided brake lines and not worry about a soft brake pedal afterwards :rock:

Good luck,

Jon aka 69mach1
 
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JethroJK

New member
Eddie, great write-up. So if I am only replacing my front brake lines, I only need to bleed the front brakes?
 

JethroJK

New member
Absolutely , if your just doing the front you don't have to touch the rears at all. Just be careful not to strip the bleeder nut those little bastards can round out very easily.


Sent from my JK

Good info to know. I am going to take it easy on those bad boys.
 

wayoflife

Administrator
Staff member
On my write-up, I show the open end of the wrench being used on the bleeder valve as, at the time, it was easier to hold with my left hand an shoot with my right. However, if you use the closed end, it'll help ensure you won't round it off.
 

Rugged4

New member
Great write up, when I changed mine I notice a lot of dirt in my tank. Is there away to clean that out so when I put clean fluid in its not mixing with dirt right away? The top by the filer is easy, but the lower chamber not so much. 07' Sahara
 

pastorwug

New member
Great write up, when I changed mine I notice a lot of dirt in my tank. Is there away to clean that out so when I put clean fluid in its not mixing with dirt right away? The top by the filer is easy, but the lower chamber not so much. 07' Sahara
I've used a turkey baster suction to pick up some of the dirt at the bottom making sure I don't remove too much fluid, though when I change anything on the brake system I usually bleed all four corners with new brake fluid until the passenger rear corner is clear fluid (meaning new fluid) and no bubbles, then I do the other corners. Brake fluid is supposed to be flushed every several years I believe.
 

RedneckJeep

New member
Would it be a good idea to use some PB Blaster or WD-40 on the bleeder valve nut to loosen it up and prevent stripping, or no? Please respond ASAP, thank you!
 

OverlanderJK

Resident Smartass
Would it be a good idea to use some PB Blaster or WD-40 on the bleeder valve nut to loosen it up and prevent stripping, or no? Please respond ASAP, thank you!

The bleeder valve shouldn't be that tight that you need it. I can easily get it off with an open end wrench.
 

Devallee

New member
This is an old thread I know... But my brakes are a little soft and I wanna bleed em but quick question... Do you open the fluid resivour or keep it closed the whole time? I've heard both but not exactly sure which is best

Sent from my Galaxy S37
 

OverlanderJK

Resident Smartass
This is an old thread I know... But my brakes are a little soft and I wanna bleed em but quick question... Do you open the fluid resivour or keep it closed the whole time? I've heard both but not exactly sure which is best

Sent from my Galaxy S37

Doesn't matter. Just make sure it doesn't dry. I normally leave it open so I can watch it better.
 
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