Brake Problem

[Pruman]

I searched through about 7 pages of threads and didn't see what I was looking for, so if there is something beyond that, I apologize. I started having issues with my 79 CJ7 brakes out of the blue. I went to stop and virtually nothing happened. I originally rebuilt the MC then decided to buy a new one and install it. After bleeding the system probably 5-6 times, I still have to pump the brakes several times to get them to apply properly. I have a Chiltons manual and have followed the bleeding procedure exactly as it described. As a side note, a few months ago I changed brake lines, bled them and it worked just fine. That makes me pretty confident I know how to bleed them. I'd like some advice on what may be the issue. Maybe the new MC is not functioning properly? Thanks in advance.

 

[Project86]

If the brakes are still spongy then there is still air in the system. You might try gravity bleeding. It takes longer but sometimes it's the only way especially if you are working by yourself. Just don't get side tracked and let the MC go empty. The last time I had the lid off the master cylinder I was able to slightly work the brake pedal back and forth like by no more than 1 1/2" and was able to see tiny bubbles coming up. So I knew there was still air. Between that and gravity bleed I got it out.

 

[gert]

bleeding brakes are a pain, i took mine to a shop that had a pressure bleeder and they got my pedal real nice, before that i was having a real hard time getting the last air bubbles out as well

 

[Pruman]

Thanks for the information. I will go back to work on it and see what happens.

 

[caveman]

If the brakes come up firm after you pump them up, you may have to adjust the brakes if they are still the drum brakes on back.

 

[jbaker4341]

I had a terrible time getting my CJ7 brakes to bleed. what i found out is i had to take off the caliper and rotate the caliper back and forth to get the air out. it would not bleed the air out for nothing bolted down. jusst put a block of wood or something between the pads.

 

[gert]

I had a terrible time getting my CJ7 brakes to bleed. what i found out is i had to take off the caliper and rotate the caliper back and forth to get the air out. it would not bleed the air out for nothing bolted down. jusst put a block of wood or something between the pads.

Dang that’s an interesting idea


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[JeeperChris]

I read recently that there are two types of calipers, one that needs to be tilted like yours and the other has the bleeder at a higher point.

 

[Patrick]

There’s only two reasons for unsuccessful brake bleeding: You are doing it incorrectly or you have defective components, that is it. We are going to assume that all your components are okay and that you have an assistant who can follow simple instructions. Follow this procedure without deviations:

1. Start with a full reservoir and at the farthest wheel from master cylinder. Get down under with the right wrench and attach flexible hose to bleeder and the other end to a small bottle.

2. Have assistant apply firm pressure on brake pedal AND HOLD THE PRESSURE UNTIL INSTRUCTED TO RELEASE!!!

3. Carefully loosen bleeder until you see air and fluid come out through hose and then re tighten.

4. Instruct assistant to release brake pedal.

5. Go back to step two and do this about three times and refill reservoir as necessary. Continue doing this until no air comes out, only fluid.

6. Go to next wheel farthest from master cylinder and start at step 1 and repeat for remaining wheels.

That is it. Simple, isn’t it? If after the bleeding procedure the pedal becomes spongy again or slowly creeps to the floor, then there is a defective component. These are the possibilities: Internal leak on master cylinder or defective wheel cylinders. Defective wheel cylinders do not necessarily have to have an external leak. They might allow air in when the pedal is released, but make a good seal when pedal pressure is applied.

 

[hole]

I had trouble years ago, my solution is in this thread https://www.jeep-cj.com/forums/f19/what-proper-way-12118/?highlight=bleeding+brakes
Cant tell you why it works, but it did

 

[Patrick]

“I had trouble years ago, my solution is in this thread https://www.jeep-cj.com/forums/f19/w...leeding+brakes
Cant tell you why it works, but it did”


Other than involving an extra and unnecessary step, there is nothing wrong with that.

 

[Pruman]

In the end, it was an issue with back brake adjustment. Bleeding the brakes just didn't seem to be logical since I had performed it prior to this with no issues. Because it happened all at once and the original master cylinder was pretty rusty, I started there when I should have taken a look at the entire system first. Thanks to everyone who responded with some great advice and helpful information.

 

[Patrick]

Good news! Once again, the conclusion to the issue was posted. Right on!