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Thread: No brakes on truck....

  1. #1

    No brakes on truck....

    I have an older Ford Explorer and it sat for a while. I went to drive it in the snow and the brake pedal went to the floor as I backed out. In looking, it left a line of fluid on the ground. I parked it and it sat for 2-3 more months until I had time to deal with it. The rear metal line was corroded. I bought a new line, replaced it, bled the brakes and had no pedal at all. Worked on it for a while, on and off, bleeding over and over and over. Still no pedal. Figured the calipers were seized up anyway, so bought new hydraulic lines and new calipers and pads. Installed new hydraulic lines, new calipers, new pads, bled the brakes about 5 or more times. No pedal. Well, I say no pedal, but which the truck off, I get pedal, as soon as start it, the pedal goes all the way to the floor and I literally don't have any brakes, other than the friction on the pads themselves.

    Figured it was only two real pieces left, the master cylinder and the brake booster, and it's my understanding that the brake booster just makes the pedal easier to push, so I put a new master cylinder on. Bench bled it, installed it, still no brakes.

    I have one of those pressurized canisters that you put on the master cylinder and it allows you to bleed the brakes by yourself and really well, and when that's hooked up, I'm not losing any pressure on the top side of things. No air appears to be coming out. I've pushed about 2-3 quarts of fluid through it all and still, no brakes.

    I've asked a number of people a lot smarter than me about it and everyone seems to be stumped. I've googled over and over and have yet to find a solution.

    Could I just be missing an air pocket somewhere? Wouldn't I at least have some pedal?

    Any ideas?
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  2. #2
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    WHen you say that you pushed fluid through it, do you mean all the way through and out the bleed ports at all the brakes? Because all the brake lines need to be full of fluid

  3. #3
    Oh yeah, I've pressurized it with the tank thing, and then bleed the lines until it's nothing but clean, new fluid coming out the lines, no air, starting in the back passenger side, then the back driver, then the front passenger side, finishing with the front driver's side, as per the instructions for this vehicle.
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  4. #4
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    I'm no mechanic by trade, more of a shadetree mechanic, and what you did all makes sense. I did a quick search and found this video on you tube. Maybe the adjustment to the pushrod will fix ya

  5. #5
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    You did pump the pedal?

  6. #6
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    I'm not sure how ford brakes work but I had the same problem on a vw after replacing calipers. The rear calipers are adjusted by operating the parking brake. Every time you operate the parking brake it would ratchet the caliper piston in a bit to take up the excess gap. Without the proper adjustment there was too much gap between the pad and rotor for the brake pedal to fully set the brake. I also had gotten a bad rebuilt caliper that the adjuster did not work once I replaced bad caliper and adjusted rear adjusters only took a few pumps to bleed them. Did your rear brake calipers have the Pistons that you have to screw back in?

  7. #7
    Quote Originally Posted by Tom M King View Post
    You did pump the pedal?
    You don't have to with the pressurization tank auto bleeder. You take the top off the master cylinder and put this device on it that seals. Then it has a pump up tank that the fluid is in and you pump it up until it has 15 lbs of pressure on it, which mimics pumping the brakes.

    Phillip, it's 4 wheel disc brakes, I don't believe there is any adjustment like that.
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  8. #8
    Quote Originally Posted by Scott Shepherd View Post
    You don't have to with the pressurization tank auto bleeder. You take the top off the master cylinder and put this device on it that seals. Then it has a pump up tank that the fluid is in and you pump it up until it has 15 lbs of pressure on it, which mimics pumping the brakes.

    Phillip, it's 4 wheel disc brakes, I don't believe there is any adjustment like that.
    But it sounds like you couldn't pump the brakes even if you wanted to since the pedal is stock( all the way down) to the floor.

  9. #9
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    Quote Originally Posted by Scott Shepherd View Post
    You don't have to with the pressurization tank auto bleeder. You take the top off the master cylinder and put this device on it that seals. Then it has a pump up tank that the fluid is in and you pump it up until it has 15 lbs of pressure on it, which mimics pumping the brakes.

    Phillip, it's 4 wheel disc brakes, I don't believe there is any adjustment like that.
    The S series Saturns with 4 wheel disk brakes had a parking brake system similar to the VW. Scott, If your Explorer is anything like the one my supervisor had it's not like that at all.

    Somehow I have a feeling that the ABS pump/system is messing with you. It does have ABS, right? If not the only thing I can come up with is one of the bleeders isn't in a high point and leaving a pocket of air in the caliper after you've "bled" it.

    I saw that happen on a Dodge van once, when a caliper was replaced with the wrong one and that placed the bleeder in a low spot. Take a good look at the caliper pistons and the location of the bleeders, making sure all pass the smell test.

    -Tom

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    If the cylinders in the calipers have been pushed back into their housing and are not touching the rotors after you were done bleeding the system, when you step on the pedal, it will go all the way to the floor until you pump enough fluid into the system to push the cylinders out so the pad touches the rotor for all eight cylinders and pads.

    If you have a leaking cylinder it will do the same thing as a ruptured break line.
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  11. #11
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    pressure bleeding works great especially for only one person, however you can still have an air pocket in the master cylinder that cannot be pushed through the lines and out a bleeder. Air can get trapped where it cannot be worked out with just the pressure bleeder. Work the pedal slowly down with the pressure bleeder connected. Fully down to the floor maybe a couple of times with a bleeder screw cracked open slightly. This will let the master cylinder push any trapped air into the lines so it can be pushed on out. Even better if you might have one is the master cylinder bleeder that has a vinyl hose on a plastic threaded fitting to bleed the master cylinder. Typically get these with a replacement master cylinder to bleed it before hooking the metal lines back to it. I have saved most over the years because they are sometimes handy for stuff like this. Disc brakes are unforgiving of any air in the system.
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  12. #12
    Thanks for the suggestions. I'll look into those. What I can't understand is why, with the truck off, I have good, solid pedal, but once I start it, then the pedal goes to the floor. It was have ABS, but it appears that most advice says if the ABS light isn't on, or throwing a code (which it isn't), then the ABS part is fine and you should just bleed it. We suspect that it's still air trapped in there somewhere, and I've heard a number of stories like this where people have really fought hard to get the air out and some times, they can really be difficult to get out.

    I'll take a couple more passes at it and see what we can do, but I still don't understand why I have pedal without it on, but no pedal with it on.
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  13. #13
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    I know what you are talking about, and you get a similar result from most vehicles that use vacuum booster for the power assist. Once the vacuum reserve gets depeleted the pedal will become harder to push and not push down as far. Starting the engine while holding the pedal down and vacuum gets restored the pedal will again go down further.
    I don't know what magnitude the vacuum booster increases the applied pressure versus without, but consider several rubber hoses that can swell slightly from the much increased pressure when booster is working. Any air will compress and create a spongey feeling pedal. If I remember right it is common for the rear most section of the master cylinder to be a problem if any air is still in it.
    If it works right brake fluid in that section will push the piston forward for the front section. Should there be a leak in the back section (or air) then that piston will move forward when the pedal is pressed until it actually contacts the front piston and mechanically push the front piston rather than hydraulicly pushing it. That causes a much lower pedal than normal, but is apart of the design of the split system as opposed to the older systems that had only one line on the master cylinder. In them if a hose ruptured ANYWHERE or fluid loss you lost ALL braking. The dual system splits the system into two seperate systems so if you loss fluid on one half the other will still provide some brakes.
    Last edited by Mike Lassiter; 06-25-2015 at 8:50 AM. Reason: tablet caused typos
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  14. #14
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    this will help explain my post and shows a cross sectional view of a master cylinder and also points out another possible problem - but I'm not sure if it would apply since you are using a pressure bleeder it would push the rear piston back I would think.

    From Federal Mogul: http://www.federalmogulmp.com/en-US/...stallation.pdf
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  15. #15
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    I'm with Tom re the ABS system. If the pedal doesn't bottom with the power off but does bottom with the power on, what changed re the brake system? Electric and vacuum. Is there a fuse you could pull on the ABS and see if that helps?

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