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  1. #1

    Default No Brake pressure

    Hi,

    I can't fix my brakes on my 1980 Mustang. The Problem is:

    If the Engine is running I have no brake pressure and if ts off I got brake pressure . There are no leaks in the linings and it comes no air out of the bleeders, i changed the Master cylinder for 3 times ( Rockauto) and I always benchbleeded it.

    The wheel cylinders and hoses are new. The brake shoes and pads are good. I have no idea what's the problem with the brakes.

    It is my first Foxbody , so is it necessary to do something special on the brakes that I don't know?

    Greets

  2. #2

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    Fwiw, the only correct way to bleed any brake system is to pressure bleed the system.
    There are a number of mechanical/fluid engineering reasons why the other methods are "by luck", and not by design.


    Thankfully, people can buy an inexpensive pressure bleeder that works fine 99.99% of the time. So, unless you're a professional, it'll do the job fine. :-)


    Note: The kit below is for the older cast iron master cylinders, not the newer type of master cylinders that have a poly reservoir top (like an SN95 brake upgrade would have).
    https://www.motiveproducts.com/pages/application-guide

    https://www.amazon.com/Motive-Produc...dp/B00CJ5DY16/
    Motive Products 105 Brake System Power Bleeder
    Price: $68.99







    Fwiw, I use the professional K&D dual diaphragm pressure bleeder, with $$$ adapters.

    https://www.amazon.com/GEARWRENCH-37...dp/B003U459B8/
    https://www.amazon.com/Power-Probe-B...dp/B000P72CSQ/

    Imho, life is too short, and brakes are too important, for me to be screwing around with the other non-OEM/non-ASE approved methods.


    I used to do the 2-person method, until one day, I could not get all of the air out of a new rear brake line on my T-Bird. WTF?!? I spent a day trying.
    The next day, my neighbor, a long-time mechanic for the State, brought over his professional pressure bleeder and adapters, and we were done before I knew what happened.
    WOW!!
    Since then, I learned, use the tools the professionals use :-), not the "I'll save some money" tools/methods/hacks that many people on the interweb suggest.


    I also, have the Motive pressure bleeder. If I have to do a front caliper change in the winter in the cold, it's a good way to do a quick bleeding job, until I can do a proper 4-wheel bleed, full fluid flush, with my K&D dual diaphragm bleeder.
    Imho, the Motive pressure bleeder is fine, and much much better than any of the so-so other methods that people use to bleed brakes.


    Good Luck!
    Last edited by stangPlus2Birds; 05-04-2021 at 03:01 AM.

  3. #3
    Moderator wraithracing's Avatar
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    We will have to agree to disagree on this one! I have personally used the exact pressure bleeder you have shown that my buddy owns. We have used it on several of his vehicles including a 1986 SSP, 1984 Bronco, 1986 F150, and several others. The bleeding job on everyone has been subpar at best! Maybe we don't know what we are doing, maybe something is wrong with his setup, who knows. Bottom line is I wouldn't get you 10 cents for the whole dang thing.

    Every one of the vehicles listed above I have gone back after using the pressure bleeder and done it my old school way of tight fitting rubber hose connected to the bleeder screw. The other end of the hose submerged in brake fluid in a one quart cup. I open the bleeder screw and then slowly depress the brake pedal 8-10 times, but never going completely to the floor. Refill the M/C and repeat as needed. Every time the bleed job is 1000 times better than the pressure bleeder has ever been. May not be the quickest, the easiest, nor the most modern, but it works EVERY TIME!

    I know pressure bleeding has its benefits and is definitely faster. I would bet that a good quality unit can do an excellent bleeding of the brake system. But IMHO and in my experience the Motive unit is crap and isn't worth the time nor the money. Again your experience obviously is different. So keep doing what works for you. For those of us who don't have or don't want to purchase a tool like that, my method works extremely well and has never failed me in over 35 years of playing with cars.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  4. #4
    FEP Super Member Bryan Knebworth's Avatar
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    Quote Originally Posted by wraithracing View Post
    We will have to agree to disagree on this one! I have personally used the exact pressure bleeder you have shown that my buddy owns. We have used it on several of his vehicles including a 1986 SSP, 1984 Bronco, 1986 F150, and several others. The bleeding job on everyone has been subpar at best! Maybe we don't know what we are doing, maybe something is wrong with his setup, who knows. Bottom line is I wouldn't get you 10 cents for the whole dang thing.

    Every one of the vehicles listed above I have gone back after using the pressure bleeder and done it my old school way of tight fitting rubber hose connected to the bleeder screw. The other end of the hose submerged in brake fluid in a one quart cup. I open the bleeder screw and then slowly depress the brake pedal 8-10 times, but never going completely to the floor. Refill the M/C and repeat as needed. Every time the bleed job is 1000 times better than the pressure bleeder has ever been. May not be the quickest, the easiest, nor the most modern, but it works EVERY TIME!

    I know pressure bleeding has its benefits and is definitely faster. I would bet that a good quality unit can do an excellent bleeding of the brake system. But IMHO and in my experience the Motive unit is crap and isn't worth the time nor the money. Again your experience obviously is different. So keep doing what works for you. For those of us who don't have or don't want to purchase a tool like that, my method works extremely well and has never failed me in over 35 years of playing with cars.
    X2!
    I agree with Trey, This method works best

  5. #5
    FEP Power Member mcb82gt's Avatar
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    How do you get the proper tight fitting connection at the bleeder though? That is the most critical thing.
    Mike

    Now stang-less.

    88 Cougar 5.0

  6. #6
    Moderator wraithracing's Avatar
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    Quote Originally Posted by mcb82gt View Post
    How do you get the proper tight fitting connection at the bleeder though? That is the most critical thing.
    If your bleeder screw is loose fitting, you may need to replace with a new one. Generally only 1/4 turn loose is all that is needed for fluid to flow. Any more than that and you have leakage around the threads in my experience. I have used some teflon tape in extreme situations, but most often a new bleeder screw will solve any issues. I use rubber hose/vacuum hose to attach to the bleeder screw and make sure that it's a tight fit. I am almost always doing this solo, so I need the hose to not come off when I depress the brake pedal. If you have a helper this method goes much quicker as the second person can view when you stop getting bubbles in the catch cup. I generally just run 1 quart of brake fluid through the system. That makes sure the system is fully flushed and by that point, I have gotten all the air out too. Just make sure to not let the M/C get low on brake fluid and suck air, otherwise you get to start all over again. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  7. #7

    Default

    I have the motive pressure bleeder, sometimes I have my wife pumping the pedal.
    have had good luck both ways.
    79 Zephyr, 4v/4r70w swap planned, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs.

  8. #8

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    Teflon tape or brake grease will seal those leaking threads enough for bleeding. I use the tape normally.

    Kenny

  9. #9
    FEP Super Member gr79's Avatar
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    These cars have basic conventional design brakes like any other domestic brand since late 60's until the anti-lock era.
    If car is recently purchased, funky brakes may be the reason it was sold?
    First thought of excessive brake pad/shoe clearance. A mechanical problem rather than fluid related.
    Pedal rod to m/c, proportioning valve issue. Engine off, harder or higher pedal is normal.
    Maybe has something to do with the brake booster behind the m/c. Clue is engine on/off pedal behavior.
    Check valve, supply hose, booster itself. One test is start engine with foot on brake pedal. Should feel it drop a bit.
    Can always take it in to a good shop. Strange symptoms can be beyond any of our DIY skills but not a certified mechanic.
    Brakes are a safety item. Money well spent. Even a temp lifestyle change is justified to pay down a charge card repair bill.
    I break down large repair costs for labor and parts on a card as if they were extra monthly car payments.

    Pressure bleeders:
    Have had success doing slower solo conventional brake bleeding with correct results.
    thanks for reminding me to experiment with garden sprayers for fluid transfer. Bought several new ones cheap.
    Adapt wand or fab custom fill assy with ball valve for ATF or even 80w gear lube, rather than pushing a bottle pump 100x per qt.
    Some have added a schrader valve and pressurize with a little 12v air compressor.
    Also considering drilling holes in floor pan near the trans and diff fill plugs. Gravity feed lube from in car.
    Cap the new access holes with the same round or oval rubber body plugs as is done in other floor pan areas.

  10. #10
    FEP Senior Member
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    Default

    Quote Originally Posted by bavaria View Post
    Hi,If the Engine is running I have no brake pressure and if ts off I got brake pressure . There are no leaks in the linings and it comes no air out of the bleeders, i changed the Master cylinder for 3 times ( Rockauto) and I always benchbleeded it.
    What do you mean when you say you have no brake pressure? Do you mean that the pedal goes all the way to the floor with the engine on and the brakes will not hold the car in place or do you mean you have no fluid coming out of the caliper and wheel cylinder bleeder screws with the pedal depressed?

    As mentioned the brake pedal will feel different with the engine running as you have the power assist. With the engine off there will be some residual vacuum in the booster, but that usually dissipates within one to two presses of the brake pedal. After that the brake pedal will feel much stiffer with the engine off.

    Can you jack up a front wheel and have somebody press the pedal while you check by hand to see if it will rotate with and without the pedal depressed with the engine running and not running?

    The brake system on your car is pretty simple and there isn't any magic to it. Is the system set up like it was originally or have you changed things on it like calipers, master cylinder, power booster, etc?
    '89 XR-7 5 Speed
    '95 SC 5 Speed
    '91 Crown Vic P72 351W
    '97 Thunderbird
    '85 Ford LTD Squire

  11. #11

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    Could the power brake booster have a vacuum leak?

  12. #12
    FEP Supporter Broncojunkie's Avatar
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    Quote Originally Posted by Foxy 83.5 View Post
    Could the power brake booster have a vacuum leak?
    I would think a vacuum leak would cause the brakes to be hard, not soft.
    79 Pace Car - 331, t5
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  13. #13

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    Thanks @ all for the advices. The pedal sinks to the floor if the engine is on and I depress the pedal. Brake fluid flows out of every Bleeder screw , if I open it.
    At the weekend I m going to try the way from wraithracing and i hope it works.

  14. #14
    Moderator wraithracing's Avatar
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    Definitely sounds like you either have air in the system or you have a leak in the system. You could have a bad M/C that is bleeding internally or even leaking into the Power Brake Booster. If you are losing fluid and don't have any puddles on the ground that would be the first thing to check. Hopefully its just a lot of air in the system and bleeding fixes the issues. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

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