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  1. #1

    Default Air STILL In The Brake Lines?!

    So, last year I put all new brakes and lines on my car. You might remember I had some trouble bleeding them. First I tried my Motive power bleeder and opened the passenger rear bleeder screw. I made a video of all the little bubbles consistently flowing out with the fluid. I had a clear tube attached to the bleeder so you could really see it. I let that go for a SUPER long time, and it .... NEVER ... changed. Maybe the problem was the power bleeder. Don't think so, but maybe. So I switched to the 2 man brake bleeding method. I've been trying to use the method where you attach a tube to the bleeder so it doesn't just go all over the place and mess up my nice painted calipers. Bled the hell out of them and was never that satisfied with what I was seeing. Gave up on the tubes and bled some more. Maybe they were good, maybe not. I don't freakin' know. Then it came time to set my adjustable proportioning valve. Opened it a little and drove. Opened it some more. Opened it some more. Opened it some more. It was now ALL the way open. Never did get the rear to come around on me. Even on a dirt road. Gave up. Drove it that way for the rest of the season, which didn't turn out to be much because of the fuel leak's reappearance, but nonetheless.

    So that brings us to today. After all this year's projects, I'm just about ready to put her on her wheels. Thought I'd attack the brake problem again (if there is one?). First, I tried the vacuum bleed method where you attach a vacuum pump and reservoir to the bleeder screw. The direction say you should be able to get fluid out when you pump it up and open the bleeder, although it was vague on which order you go in and whether you would need to keep pumping after opening). I never did get more than a tiny bit of fluid in the bottom of the reservoir, and then after that, it refused to pull any more. WHY?! I tried several combinations of adapters and it WAS able to pull a vacuum before I opened the bleeder. But then it would disappear immediately and not much else would happen.

    So, I thought i would try just opening the bleeder with the tube on and see if i could get any to flow out. Nope. Jacked the car with the nose in the air. Still nope. Gave up on the tube and opened it. It dripped immediately. All over my nice painted caliper. ARGH.

    Is this normal? Can you not actually use the tube method?! Last time I had guys telling me maybe I opened the bleeder TOO FAR and that's why I was always seeing bubbles in the tube. I'm second-guessing everything here. It seems REALLY wrong to me that the proportioning valve can be adjusted ALL the way open. It makes me think there's a big-assed bubble somewhere making things all out of proportion. I know I've got fluid at all 4 corners, and the rear brakes DO seem to be working, but it just doesn't seem right to me.

    Thoughts anyone?

    In the meantime, I've got myself a s***load of brake fluid and a helper, so I'm off to bleed the LIVING F*** out of my brakes. GRRRRR
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  2. #2

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    No, it should be pretty easy to see air bubbles on a clear line. If you aren't getting any fluid, something is blocked off or the master cylinder must be leaking.

    I'd try cracking apart brake lines until you get fluid.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  3. #3
    FEP Senior Member BMW Rider's Avatar
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    Sometimes if there is a bubble in the caliper it can be hard to get it to clear if the piston is partially extended. Try cracking the bleeder and pushing the piston back fully, then bleed everything again.

  4. #4

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    There IS fluid there, but apparently the stupid vacuum pump can't pull it out for no reason. I did my normal 2-man bleed and you do get fluid. It's just things like the vacuum bleed problem, the fact that fluid is reluctant to go into a clear tube with gravity, as opposed to just dripping and making a mess, and the thing with the proportioning valve being wide open just leads me to think something's not right SOMEWHERE in my brake system. I don't think there's a leak (at least not externally) because I'm not losing any fluid.

    I did take the car for a short drive after doing the bleeding. The brakes feel the same to me, although it has been a good 9 months since I drove it last. And when I got back, there was a nice hot smell around the area of the rear brakes. I haven't investigated why yet, but that's pretty irritating.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  5. #5

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    Quote Originally Posted by BMW Rider View Post
    Sometimes if there is a bubble in the caliper it can be hard to get it to clear if the piston is partially extended. Try cracking the bleeder and pushing the piston back fully, then bleed everything again.
    I'll do that with all 4! They were all new last year.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  6. #6
    FEP Super Member
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    I think you have air entering the system .
    clowns to the left of me , Jokers to the right

  7. #7

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    Sounds like you are getting air through the bleeder screw threads. Wrap them in Teflon tape and try again. It doesn't work forever but will get your vacuum method working again. You can get bubble in the bleed line forever if the treads are loose.

  8. #8
    FEP Super Member gr79's Avatar
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    2x to teflon wrap bleeder treads. Thin width, away from taper end.
    Tiny bubbles usually come from air sucked thru bleeder screw treads.
    Also can come from loose bleed tubing at bleeder. Has to be tight fit.
    Big slugs of air are from the brake line.
    Open bleeder 1/4- 1/2 should be enough. MC resv has to be topped off after say 10 pumps.
    Usually have cleared bubbles after 12-20 pumps. No need to churn fluid. Pump and let up smoothly.
    Keep end of bleeder tube well submerged in fluid. Letting up on the pedal sucks fluid back up.
    Cycle pedal until air is cleared out.
    The clear tubing has to be solid fluid, no bubbles except nano bubbles for lack of a better word.
    Tubing is now a see thru extension of the brake line.
    Close bleeder at leisure.

  9. #9
    FEP Super Member erratic50's Avatar
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    Did you try cursing at it?


    Just bet your buddy $5 bucks they can’t figure out what’s wrong then happily lose.


    In the past when ive has suck problems I’ve put acquarium tunes on the bleeders and put them into a bottle of brake fluid then pumped the brakes good a few times to start the siphon effect then kept fluid levels at the master cyl to where it can’t suck air.

    once you’re ok with what you get out close the bleeders and try it

  10. #10

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    Quote Originally Posted by erratic50 View Post
    Did you try cursing at it?
    Maybe too much?

    Lots of good ideas here so far. Thanks!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  11. #11
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    Bleeder screw full of crud?

  12. #12

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    Quote Originally Posted by darkd0r View Post
    Bleeder screw full of crud?
    Possible but not likely. All of the calipers are new. I will check them though.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  13. #13
    FEP Senior Member Tigger's Avatar
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    I had a problem bleeding the drum brakes on my Saleen last year when I put the rear end back in. Passenger side would not bleed out. My son and I bled them a bunch of times and still had air. I finally snugged down the metal line into the wheel cylinder and no more air. It only turned a tiny bit but it was enough to get them bled. It was not leaking fluid either. Maybe try and snug up things and see if that helps.
    67 Mustang Coupe
    96 Tangerine GT
    86 Saleen #179

  14. #14

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    I do not like using vacuum bleeders due to problems with them sucking air through the bleeder screw threads. I have never worked on a Mustang that could not be successfully bleed by using a standard 2-man pressure technique.

    Most likely you have air in the m/c. Bench bleed that on the car by loosening and tightening the outlet nuts. No need to remove the lines. Then bleed all four brakes again.

    It wouldn't hurt to post a photo of your front calipers installed on the car so we can be sure that they are on the correct side. If they are Fox calipers, the bleeder screws need to point rearwards, NOT upwards.
    Jack Hidley
    Maximum Motorsports Tech Support

  15. #15

    Default

    I was afraid of that. I used this kind of cheapie bench bleeding kit before putting the m/c back in last year, and I was not confident it had done a thorough job. I'll definitely do that too.

    I'll take some pics of the front calipers tomorrow. They are '94-98 GT style.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  16. #16

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    Welllllllllllll, I found a leaking caliper piston seal at the right rear. Didn't get enough time today to do anything but replace it. Bleeding, etc has to wait. I was able to warranty the caliper at Napa which was cool. I feel good about this though! I think we might have it licked!

    Here's a pic of a front brake.

    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  17. #17
    FEP Super Member gr79's Avatar
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    Good deal
    Air brakes are for trucks.

  18. #18
    FEP Super Member gr79's Avatar
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    oops double post

  19. #19

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    Finally got around to doing some bleeding today. I pumped a boatload more fluid through the system with my pressure bleeder. I didn't have the tiny bubble problem this time. The pressure still seems oddly weak at the rears. I looked back at this thread:

    http://vb.foureyedpride.com/showthre...ling-New-Lines

    It strikes me as odd that I had more pressure back then. I believe I had the adjustable proportioning valve adjusted such that it was opened just a bit. I had had it all the way counter-clockwise (what I believe was "closed") while I replaced the lines. I turned it a little bit clockwise before doing the bleeding last time. Then, during the course of driving it to set the prop valve, i "opened" it more, more, more, until it was all the way "open". Am I wrong about that? Is it now all the way closed? The label on the knob says "Less Brake" and points counter-clockwise, so my assumption was that the more you turned it that way, the more closed it is. But, the pressure at the rear bleeders seems to indicate otherwise!

    Anyway, the thing is relatively safe to drive at this point as long as I don't do any crazy tailgating or anything, so I'm going to drive it around and mess with tuning that prop valve and see what happens.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  20. #20

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    Brad,

    I've never tested this to be absolutely sure, but I'm 98% sure that it is correct.

    The position of the proportioning valve knob can't have any affect on bleeding the rear brakes. The lowest breakpoint pressure setting for the prop valve is around 300psi. When the rear bleeder screw is open, only maybe 20 psi of pressure can develop in the rear brake system, so the prop valve can't be reducing the pressure since you are no where near even the lowest possible breakpoint pressure.

    When you rotate the prop valve knob in the direction of "less brake", this lowers the breakpoint pressure.

    What model and brand prop valve is in the car?
    Jack Hidley
    Maximum Motorsports Tech Support

  21. #21

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    Good to know about the pressure.

    It's a Ford Racing one for a Fox Mustang from probably 10 years ago. I'll see if I can find a model number.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  22. #22

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    It's either Kelsey-Hayes or Wilwood. Either is fine. The only bad ones I know of are SSBC.
    Jack Hidley
    Maximum Motorsports Tech Support

  23. #23
    FEP Super Member
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    When I swapped Sn spindles and brakes onto my 84 , with ranger 10" drums and hardware ,
    I had to extend the push rod for the master cylinder just the slightest , to get full form pedal .
    Another thought , is what kind of vacuum are you pulling at idle ?
    With a cam that does not produce a lot of vacuum , large over lap , your booster may not be filling entirely , which can be verified if you get better brake feel with a second pump of the pedal when applying the brakes when coming to a stop .
    clowns to the left of me , Jokers to the right

  24. #24

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    Quote Originally Posted by ashley roachclip View Post
    When I swapped Sn spindles and brakes onto my 84 , with ranger 10" drums and hardware ,
    I had to extend the push rod for the master cylinder just the slightest , to get full form pedal .
    Another thought , is what kind of vacuum are you pulling at idle ?
    With a cam that does not produce a lot of vacuum , large over lap , your booster may not be filling entirely , which can be verified if you get better brake feel with a second pump of the pedal when applying the brakes when coming to a stop .
    Right now it has the stock HO cam (i think--whatever came with my well-worn parts car). I haven't started this year's engine project yet.

    How far do you think you adjusted the pushrod exactly?
    Last edited by ZephyrEFI; 07-18-2018 at 10:21 AM.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  25. #25

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    Ugh. Well I've been driving it a lot this weekend. I did have occasion to slam on the brakes in traffic on Friday. The response was... underwhelming. I guess now we're on to replacing the master cylinder.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

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