Folks,

I am currently restoring a '39 Deluxe Sedan and have been recently doing the brake work. I have rebuilt all four wheel cylinders and have installed re-lined shoes. I topped off the master cylinder and attempted to bleed the brakes and had zero pressure in the pedal. The master seemed to be leaking at the dust boot, as I could see air bubbles and fluid coming through a crack in the rubber boot. I removed the master, honed it out nice, and installed a rebuild kit. I got it back in the car, re-filled it and still zero pressure? I know there must be a lot of air in the system, as I have rebuilt all the wheel cylinders as well as the master, but when I try to bleed them, I do not even hear any air coming out, and no fluid comes out at all. Any ideas what could be the problem?

Dan

What method aare you useing to bleed the system? You say "no fluid comes out." Are you sure the hoses are not full of crud?

what did you replace when you overhauled the cylinder . was there a releif vave in the kit . apart from that if there is fluid and air coming from the rubber boot it sounds as if the piston cups are still not sealing , are you sure there is stll no pits or groves in the cylinder.

As far as method, I am opening the bleeder on one wheel cylinder at a time, then having someone slowly push down on the pedal while I have it open. I then have them hold it down until I close it again, then let the pedal up, then open the bleeder again, and have them slowly push down again, etc. Until the air is bled out and just fluid comes out. I would repeat the process on the other wheels.
As far as the rebuild kit, there was the part that goes in first, not sure what it is called, the new spring went in next, then the new cup, then the new piston, a new washer, new retaining clip, then the new boot. No air or fluid leaks out now, but there is no pressure at all now.

Dan

Start with the wheel farthest from the master cylinder. HAve all the bleeders closed. Then have the helper pump the peddle several times and hold it to the floor. While peddle is on the floor open then close the bleeder. Repeat. If you are getting no fluid, you may want to make sure there's no obstructions in the lines. Maybe take the line off at both ends and blow air through. Do you get bubbles in the reservoir?

Thanks. I will try again next Saturday, that's the next chance I'll get to have a day off. I'm not sure, but I do not recall seeing any air bubbles in the reservoir, I'll have to watch closely when I try it again.

Dan

Just a thought, did you reassemble master cylinder internals in correct order ?

How about cracking the pipe open out of the master cylinder whilst someone pushes the pedal down to at least see if you have pressure from the master cylinder ?

CJH

If the system is completely dry it takes a lot of pumping to fill it up again. A vacuum bleeder will make things go a lot faster and easier and do a better job.

I prefer to start with the nearest wheel (left front). Open the valve and have someone pump the pedal. Keep pumping till fluid squirts out.Go do the other wheels. Then come back, and pump up pressure before opening the valve.

It helps to leave the car overnight before the final bleeding if possible. This allows all the air bubbles to separate from the fluid.

Get a piece of 1/4" clear plastic hose and stick it over the bleeder valve. Put the other end in a can or jar. This keeps most of the mess off the floor.

Of course if you use a vacuum bleeder all this is unnecessary.

O yes be careful not to pump the master cylinder dry or you get to start all over again.

Take your bleeders out and make sure they are clear. The bleed hole is tiny and easily pluged with gunk. I have found this problem several times over the years.

All great advice guys, much appreciated. I'll let you know how I make out.

Dan

From a former brake mechanic, first of all, be certain that all of the brake shoes are adjusted properly before attempting to bleed. The shoes should be almost at the point of rubbing the drums lightly. Always start bleeding with the reservoir full. Always start the bleeding from the furthest wheel cylinder from the master cylinder. Always refill the reservoir between bleeding wheel cylinders. Make certain that you do not open the bleeder until the pedal is in the process of being pushed and not before. Always re-tighten the bleeder while pressure is on the pedal or as fluid is coming out.

Okay,

I pulled the brake line at the master and pumped the pedal, and fluid pushes out, so I must be okay at the master. I was able to bleed the two rear, after some pumping and re-filling I got fluid out the two rear bleeders. Now I am trying to do the front, but no luck as of yet. Still cannot get any pressure, and still cannot get any fluid out the front bleeders. I took the bleeders out and they are clear. I do not see any leaks anywhere, and I do not see the level going down in the master. So I am still stumped here.

Dan

Exactly how are you bleeding the system?

Simple plumbing. If you have pressure at the master, and not the wheel cyl, there's only a hose and tubing in between. Crack the line at the wheel cyl, while pressure is applied. If fluid gushes freely, your cylinder is plugged. If not, your hose (or line) is plugged. Do it on all wheels that give you problems. It's common for a hose to come apart from the inside.

I had a '64 Pontiac, new from the factory, with a rear wheel cylinder that had no hydraulics hole drilled in the casting. I couldn't figure why the shoes never wore until I took it apart.

A word of warning: Don't mix brake fluids (DOT-3, DOT-4, DOT-5). You will cause yourself big problems later. If your system was designed for DOT-3, stay with it. Replace the fluid every few years, and you will never have water/rust issues.

Here is how I am attempting to bleed them;
I have all bleeders closed, I top off the master and close it back up.
I then pump the pedal a few times and release it.
I then open the master again and check the level and make sure that it is full and re-close.
I then open the bleeder of the wheel I am trying to bleed.
I then have a helper slowly push down on the pedal.
I listen for air and watch for fluid to come out.
While they still have the pedal depressed, I close the bleeder. Once closed, I have them release the pedal.
I have been repeating this process.

You're ok up until line 5.
The pedal guy should be constantly pushing, BEFORE you open the bleeder valve, and holding his foot down until you tighten your valve.

So, he pushes, you crack the bleeder, the pedal goes down and he HOLDS IT DOWN. Then you tighten the valve, and tell him to lift his foot. Repeat until all air is out.

Start with the farthest wheel from the master. The whole system only holds about a cup of fluid. When you are done bleeding each wheel cylinder, STAND on the brake pedal. It should be rock-solid with very little travel. If a hose breaks, or a leak develops, you want that to happen at home, not when you're approaching the railroad tracks.

SC is correct. You want to "build" pressure by pumping, hold the pressure, then release it at the bleeder, close the bleeder, then build again until your pedal does not get any better when pumped up. As long as you pump and the peddle gets better{ first time to the floor, second time 1/2 way, third time close to top, etc.} there is still air in the system. When the system is properly bled you should have EXACTLY the same peddle feel each time. Depth of push COULD be adjustment but it will feel the same every time. If when you are finished you can hold in on the poedle and it creepes in there is still air OR a leak. You are close to being where you want to be!!

I'm not to the point yet where I have any pressure, pedal goes to floor with no resistance.

Your lines are FULL of air. That's one reason we start at the farthest point, to get the majority of the air out.
(I assume you rebuilt your master cylinder correctly, and all of your seals work.)

Air compresses to a small fraction of its original area, so your pedal will go to the floor when you initially start. Your first pedal pressures will only give a little spritz at the wheel cylinder. As brake fluid diplaces air, the pedal will show more resistance, and less travel.

It's important to follow the previous steps. Eventually, you will get there. Even the smallest amount of air will make the pedal very spongy. With no air, it should feel like a rock.

The factory uses vacuum-fill. If the system won't 'draw down,' they can't fill (indicating a leak). A successful vacuum will suck all the air out, then fluid is pulled in, filling to the top.

You can bleed using your two-man method. Follow the steps, and it should work just fine.

I always bleed brakes starting with the nearest one, the left front. It is always hardest to get the air out at first, once you get most of the air out it is easier to build up pressure . So the closest wheel should be done first. This seems logical to me anyway, and I have been doing them this way for years with no problems.

So why do I always read that I should start with the farthest wheel and work towards the closest? I'm not saying this is wrong. If there is something I am missing out on I would like to know about it.

Hello Rusty,
Look at it this way Which line would have the most air in it? The left front or the right rear?On the single master cylinder you will be pumping fluid/air thu the system at once. There for when you bleed the right rear first you will be removeing most of the air.Just one guys way of thinking.
Vern

Because that is the proper and recommended method for bleedeng a brake system.

I guess every OEM service manual is wrong, even though they all agree with each other. What do those automotive engineers know, anyway... nothing. Educated idiots, all of them.

It's amazing that we still bleed brakes the same way, from the beginning days of closed loop hydraulic systems.

I think we're missing something. Most of the big chunks of air should have been bled out by now. In the end it doesn't really matter what corner of the car you start or end with, the air will run out. I don't usually have anybody to help me so I've just learned to open the bleed valve and watch the fluid run into a glass jar through a clear plastic tube for 30 seconds. The weight of the fluid in the master cylinder will push the wheel cylinder fluid 'down hill'. I don't let it run anything longer than 30 seconds before shutting the bleed valve and going to the master and adding more fluid to bring it up to it's full level. It's slow but it works every time.
But I always get a 'pedal' after just a few minutes of this. It seems '39 D11 must have a mechanical/hydraulic problem some where because he should have a 'pedal' by now wouldn't you think? Fluid/pressure must be being bypassed at the master. A little bit of air bubbles would still give him a decent pedal. How many of us have driven with a soft pedal? This guy has NO pedal. He should atleast have a soft pedal by now. I think the master is kaput. Most likely still assembled wrong.

I find that once I get a little pressure in the system the bleeding process goes easier and faster. And the quickest way to do this is start from the nearest wheel.

I also find, that after I bleed the brakes it pays to leave the car overnight then bleed them again. Air can dissolve into the fluid but let it set for a while and the bubbles come out to where they can be bled out.

Of course, this applies to a car that has has a complete brake job and is totally dry.

Well I'm certainly wondering at this point if I have a problem as well. The assembling of the master seemed pretty straight forward, I just followed the instructions that were included with the rebuild kit. Still, I guess there could be a problem with it. How exactly is the valve designed to function? I wonder if the problem is there? The directions said to clip the valve assembly to the return spring and insert into the master cylinder bore. It is obviously pushing fluid, but there could still be a problem? As much as I really do not want to pull the master again, I am considering doing so for a second look. Also, I notice when I fill the master right up to the top and replace the filler plug, when I push down on the pedal fluid squirts out a small hole in the filler plug like a squirt gun, is this normal?

Dan