I need some ideas.... Air in the brakes

[Magnes]

I went through the rear brakes today. Now all the rubber lines are new as well as everything in the braking system other than the prop valve and the hard lines. I checked that prop valve out and it seems to be working fine as far as I can tell. It's not leaking anywhere (had a buddy pumping the brakes as I sat under it watching for leaks or bubbles or anything strange). I am getting flow to all four corners. Checked all the hard lines for leaks and flow - all were good.

We bled it out AGAIN and were still getting too much air... Constant bubs. Annoying as hell. Ran a ton of brake fluid through the thing starting from back pass side.

I put another new master cylinder in there. Bench bled that thing using old hard lines that were bent to feed back into the master cyl reservoir. Did everything I could to keep air out (used silicone caps from my mighty vac kit on the lines and used the plastic screw in caps that came with the new master cyl) as I installed it.

After all that my friend and I re-bled the car again. Bled out fine this time. Easy as pie. Got a hard pedal this time. All the brakes are grabbing. Looks like it's fixed.

It sucks because when I bought that first master cylinder from Rock Auto, it was by far not their cheapest master. I wanted to avoid getting junk parts so I spent a little more. What I got was in fact what I did not want... A new junk master cylinder. I got this second one from O'reilly's. Hopefully it will give me years of use. Right out of the box it seemed like a better unit.

Anyway, this whole thing was a weird problem. How the pass side caliper would bleed out good with the old new master but the driver's side wouldn't - is beyond me. I have never in my life had such a hard time with a brake system. Anyway, I appreciate each and every one of you guys for bouncing ideas off me and giving me ideas for what to look for. This site has an awesome community of people and I am very thankful that I can be a part of it.

I learned a lot.... Biggest lesson though: Never assume a new part is good. Afterall, some of these "new" parts are actually quite old and have just been shelved for who knows how long. If you don't believe that, I have a "new" master cylinder I will sell you! LOL!

Thanks Again!

 

[Photon440]

You got it working! That's great news, I'm sure you're pretty happy about it.

 

[kb67mopar]

I went through the rear brakes today. Now all the rubber lines are new as well as everything in the braking system other than the prop valve and the hard lines. I checked that prop valve out and it seems to be working fine as far as I can tell. It's not leaking anywhere (had a buddy pumping the brakes as I sat under it watching for leaks or bubbles or anything strange). I am getting flow to all four corners. Checked all the hard lines for leaks and flow - all were good.

We bled it out AGAIN and were still getting too much air... Constant bubs. Annoying as hell. Ran a ton of brake fluid through the thing starting from back pass side.

I put another new master cylinder in there. Bench bled that thing using old hard lines that were bent to feed back into the master cyl reservoir. Did everything I could to keep air out (used silicone caps from my mighty vac kit on the lines and used the plastic screw in caps that came with the new master cyl) as I installed it.

After all that my friend and I re-bled the car again. Bled out fine this time. Easy as pie. Got a hard pedal this time. All the brakes are grabbing. Looks like it's fixed.

It sucks because when I bought that first master cylinder from Rock Auto, it was by far not their cheapest master. I wanted to avoid getting junk parts so I spent a little more. What I got was in fact what I did not want... A new junk master cylinder. I got this second one from O'reilly's. Hopefully it will give me years of use. Right out of the box it seemed like a better unit.

Anyway, this whole thing was a weird problem. How the pass side caliper would bleed out good with the old new master but the driver's side wouldn't - is beyond me. I have never in my life had such a hard time with a brake system. Anyway, I appreciate each and every one of you guys for bouncing ideas off me and giving me ideas for what to look for. This site has an awesome community of people and I am very thankful that I can be a part of it.

I learned a lot.... Biggest lesson though: Never assume a new part is good. Afterall, some of these "new" parts are actually quite old and have just been shelved for who knows how long. If you don't believe that, I have a "new" master cylinder I will sell you! LOL!

Thanks Again!

Glad to hear it! I learned a similar lesson recently. I bought a brand new fuel pump for my truck and within 15 minutes of completing the installation the sending unit crapped out. New parts are never flawless. Rock auto is pretty good about returns though, you should be able to send it back for a full refund on their dime. (its actually where the bad pump came from but its not their fault)

Anyway, thanks for sharing the full experience so we could all learn from it.

 

[Beekeeper]

Awesome! Glad you got some brakes now

 

[DLB70Plymouth]

I want to thank everyone who posted on this item. I took my 70 GTX apart to put new metal line, proportioning valve, master cylinder, calipers and all and could not get it to hold a pedal. I noticed the post about getting the bleed at the top and knew that was where I did not pull my head out! Thank you very much I now have pedal and moving onto getting it back on the road. I am very grateful in South Texas.

 

[Cornpatch MO]

Your symptoms were just like mine is now. everything is new, and I am not useing a prop. valve -yet. Bled the heck out of the master Cyl. just as you did. Bled all four corners as you did, and can't get completely rid of the bubbles I can't think of why replacing your M.C. fixed your problem . I have brakes at the front disc's and rear drums, but the pedal is spongy. I know there is air in the system.............................MO