Brakes won't bleed!!!

[Sam I Am]

With the lines off the master I get nice squirts from both ports.

That's not how I've always done bench bleeding.
I've always plugged the MC ports with the supplied plugs, filled the MC with brake fluid, then slowly pushed in the piston and slowly let it out, repeat pushing in the piston several times.
Attach loosely to the firewall, just get the nuts started.
Then attach the lines.
Then bolt it tightly onto the vehicle.
No squirting out the MC.

I double checked the part # that Autozone gave me and it is correct as far as their catalog goes. I'm stumped. I've never had this issue before.

That could be your biggest problem right there.
I've always thought of AZ as a "last resort" place to get parts because of the notoriously poor quality of the parts they carry.
AZ is the place to buy parts for a vehicle you don't plan to keep and want to keep it running just long enough to get it out of your yard.
And the service around here is worse than their parts.
I've never been a fan of the "standing in line twice to buy something once" policy they have.
If it was me, I would get my money back from AZ on the MC and get one somewhere else.
It sounds like it's bypassing internally because it had the wrong piston/seals installed; if as you say everything else is right, it has to be the "new" master cylinder.
But I'm not there and I can't see and feel what it is doing.

I've seen and heard of too many defective parts come from AZ.

[custom1106]

what I meant buy the squirting was after I got everything put together and bled, and still having problems... I was testing to see if fluid was still exiting the master like it should.

[70_F100]

I've waited to reply to this one.

First, I haven't bought parts from AutoChina since I had a bad experience there several years ago. I try to always buy from Advance Auto or NAPA. If you can get a Cardone rebuilt master, use that.

Second, if the cups, pistons, or anything else in the wheel is stuck, you should get pedal height, regardless. You will get pressure if you have a good master cylinder and all of the air is evacuated. The system doesn't know what is stopping the pistons from moving. It could be that the shoes are against the drums, or the piston is frozen solid in the wheel cylinder. Same result, pressure in the hydraulics because the pistons aren't moving. Have you ever blown into a baloon that is made of heavy material, versus a very flimsy baloon? You provide pressure, you can only blow so hard, so the baloon either gets bigger or not, depending upon whether or not you can overcome the strength of the latex. Either way, you can't force more air into the baloon.

You've been given what I consider bad advice on bleeding. Sounds like you've got the air out of the master cylinder, so concentrate on the rest of the system. PUMP the brakes. Don't just push once and open the bleeder. Have your "helper" pump the brakes 10-15 times with the bleeder closed, then hold the pedal down. At that point, open the bleeder. Make sure your helper knows to keep constant pressure on the pedal, and DON'T PANIC when the pedal goes to the floor, because that is DEFINITELY going to happen. DO NOT release any pressure on the pedal until the bleeder is closed. "PUMP 'EM UP, HOLD 'EM DOWN" is the method I was taught about 50 years ago. Bleed each wheel, starting with the right rear or right front, doesn't matter with dual master cylinder. If you only have a single master cylinder, it's a different story. Make sure that you bleed each wheel until there is no air or "spurt" when you open the bleeder. Continue this process through all four wheels. Regardless of whether it's a single system or dual system, use the "farthest from the master cylinder" method (really doesn't matter on dual, but it's a good rule of thumb). You might have to do this a number of times, depending on how many times you've done it and how experienced your "helper" is (remember the "Panic" part). You can also use a hose from the bleeder screw into a jar of brake fluid, but unless you're experienced, you can still miss some air in the system. MAKE SURE THE MASTER CYLINDER NEVER GETS BELOW HALF FULL!!!

Try these things, and if they don't work, let us know.

[kaptnkaos]

I have a MC bleeder kit that has two treaded pieces of nylon (plastic) with nubs sticking out.
There are two clear hoses that connect to the nubs.
With your MC held in the vice stick those hoses in the resevoir, and gently push the plunger in which will dispell the air out of the MC... hence the name bench bleeding.
Carefully mount the MC to the firewall, remove the the plastic fitting then attach the brake lines to the MC.
I'd still check the wheels to make sure everything is intact.
I have had the end that sticks into the wheel cylinder and pushes the brake shoes out pop out, causing the rubber cap to come off and let the inner cup come out...
I've done dozens of brake jobs and have only had bad problems on one.

KaptnKA S

[fordman]

drag it over here i'll fix it.

[m-mman]

Fordman, I feel the same way. I think if it were in my driveway I could get it going in short order.
BUT . . . .
We need to do this from a distance.

OK,
Hydrualic brakes work by having the MC create pressure (Pressure is a FLOW of liquid AGAINST a resistance).
If there is NO resistance there is no pressure, if there is no pressure, there is no brakes. (air bubbles prevent the build up of pressure which is why you bleed brakes)
Whatever else is going on, Your problem is still that you are NOT getting FLOW from all 4 wheels. (without a good flow you are not really bleeding)

You have described getting good flow out of the MC. It squirts out both holes. You said the rods were identical and you were getting a good squirt from both MC ports with the pedal. This means the MC is working.

I dont respect poor quality parts any more than anybody else, but if you are getting a good squirt, the MC is creating flow. And if you can create resistance you will get pressure and eventually you will have functional brakes.

The differences between hydraulic systems and electricty is very slight. If you had an electrical problem people would be telling you to trace the wires.
Well, you are going to have to trace the brake lines.

You know what a good squirt looks like at the MC, now you need to follow the brake lines to VERIFY that you have a good (bleeding) squirt at each point.

Two ways to do this.
What you should REALLY do is tighten the lines at the MC then trace the brake lines. (both of them) to the next place where they screw into ANYTHING. This should be a distrubition block mounted on the frame.
Loosten up (remove might be better) the fitting and work the pedal (just like you have been doing for so long) and see if you are getting the EXACT SAME SQUIRT activity that you are getting at the MC.

The Brake lines are hollow so whatever flow (squirt) that is coming out of the MC will be carried to the next opening. (where you removed the line) There is no place else for the squirt to go.

Once you have a good squirt at that point, tighten the line back up and follow it to the next connection, open (or remove it) and pump the pedal. Again you should get a good squirt.

Tracing the front/rear first doesnt matter, just keep following the lines and removing and checking for flow at EACH POINT. And do it for all FOUR wheels.
Keep checkign the MC so that it stays full.

IF you have a good flow of fluid through ALL the metal lines then you need to unscrew the hoses and ensure that you are getting a good flow of fluid through them too.

Is this a pain? YES!
Is this a lot of work? YES!
But as I talked about earlier you have used up all the 'easy steps' and now the real work begins.

As a possible short cut (gosh did I really suggest this?) You COULD start at the places where the steel lines screw into the rubber hoses. (two in the front and one in the rear) Remove the steel lines and see if you get a GOOD SQUIRT at these connections. Then check for a good squirt through the hoses.

Remeber the Squirt MUST be IDENTICAL to the squirt you are getting at the MC itself. The lines are hollow and there is NO REASON to have any dimished flow of fluid (squirt when pedal is pushed)

FoMoCo parts, NAPA parts, Auto Zone parts it doesnt matter.
FACT: If the MC is making a good (bleeding) squirt AND that squirt of fluid makes it way to the wheels you WILL have functional brakes again.

Difficult problems are always difficult to solve. It is not going to be easy but keep working and keep reporting and we can get through this together.

[madbiker4]

It definitly sounds like there is air in the system somewhere. As was said, if you are getting pressure at the master cyclinder you should everywhere else. one thing you can do is get some brass plugs and plug the ports on the mastercylinder. make sure it is properly bled, then see if you have any pedal. you should not be able to push it any more than half way. even though you are getting a stream of fluid it dosen't mean you are getting pressure. one other area I can think of is you said you replaced the front wheel cylinders. it is possible there is trapped air in the cylinders. remove the brake line or bleeder and use a syringe ( a clean one) to pump fluid into the cylinders, then rebleed it. if you have a leak in a line somewhere you should be able to find it easily, it will be gushing pretty good if you have no pressure. another thing, when bleeding, don't open the bleeder up so much that you have a solid stream of fluid, just barely open it so it can build some pressure and push any air up and out of the bleeder.

[fordman]

use fred flinstone brakes. yes i am trying to be funny not make anyone mad. or make fun of them.

[wildcard]

Are you sure your helper is pumping the brakes up and holding pressure until the pedal goes to the floor and holding it until the bleeder is closed as 70-F100 suggested ? That could cause them to not pump up. Just a thought. The scenario he gave is the same way I was taught years ago without any problems. Make sure the helper does his part right or it's all for nothing.

[custom1106]

i havent checked the proportioning valve yet...i heard somewhere the there might be a pin I have to pull out or push? I've been away from the truck all week, I'll get a chance to look at things more indepth in saturday. Thanks you for all the suggestions and advice.

[fordman]

your truck wont have a proportionign valve with a pin on it. unless it was put on when someone put disc brakes on it. or if it is an f250 with disc brakes it will have a similar valve with a pin to push in to bleed the brakes. that valve is located on the rear of the engine crossmember.

[jfmaz]

Maybe the length of the master cyl. to pedal rod needs adjusting?

[70_F100]

If my memory serves me right, there isn't any adjustment on the push rod, and once it's inserted, it's almost impossible to remove it because of the retainer that locks it into the master cylinder piston. If the push rod were too short, the pedal wouldn't return to the full height. If it were too long, there would be issues with that when trying to bleed the system, but he would have had trouble installing the master cylinder.

My guess is that there is still air in the system, and the brakes just aren't being bled properly.

Another thought on the bleeding issue. If you've ever watched the reservoir on a master cylinder when the brakes are operated, you should have noticed that when the pedal is released, the fluid rushes back into the reservoir and forms a "mini" guyser. I've had instances where I didn't have anyone to help with the bleeding. In those cases, sometimes I've been able to pump the brakes 20-25 strokes, making sure to let the pedal come all the way to the top on each stroke, let the vehicle sit for 5 minutes or so, then repeat the process. By pumping the brakes, the air that is in the lines gets compressed, and when you stop pumping, the compressed air forces its way back through the lines into the master cylinder reservoir. After repeating the process a few times, you eventually work all of the air out of the system. It doesn't work EVERY time, but I've successfully done it this way quite a few times!!

[kaptnkaos]

The only way there woul dbe a diffence in length of the activation rod is if it were the wrong MC... like trying to replace a MC from a drum brake set up with one from a disk brake unit.
it apears that all the parts the parts that were replaced were the correct ones.

KaptnKA S

[fordman]

as far as adjustable brqake rods. soem trucks had them and other didn't i think 67 di not have the adjustable rod. but i am not guarnateeing that.