Gravity brake bleed not working

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Shadow

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Have new master, all new slaves, empty brake lines, everything is dry except for the master which I bench bled and is full of dot 5. Have slave bleed valves open down below.
No fluid will come out of the master.
Do I need to push my brake pedal down and put a wedge in to keep it down? Even when I was mounting the master after bench bleed no fluid was coming out of it before even attaching brake lines.
 
I always do one at a time starting with the right rear and working my way closer to the master cylinder. It can take a while. The other way is to take a piece of vacuum hose coming off the bleeder valve into a glass of brake fluid one at a time and let someone pump the pedal. With the end of the hose kept submerged in brake fluid. You will see when the air bubbles stop and then move on to the next wheel.
 
I thought about doing it that way but with dry lines I’m wondering if I would just be sucking air back into master
 
Shadow said:
I thought about doing it that way but with dry lines I’m wondering if I would just be sucking air back into master
Click to expand...
Nope. It make take a minute or two though.
 
I’ll give that a try. After three days of waiting not a drop of fluid has come out of that master. The gravity method is so easy but it’s just not happening
 
Shadow said:
Have new master, all new slaves, empty brake lines, everything is dry except for the master which I bench bled and is full of dot 5. Have slave bleed valves open down below.
No fluid will come out of the master.
Do I need to push my brake pedal down and put a wedge in to keep it down? Even when I was mounting the master after bench bleed no fluid was coming out of it before even attaching brake lines.
Click to expand...
Kinda vague, could use some better info- year and brake type for instance; but here goes:
By "slaves" I assume you mean the wheel cylinders. So if you have wheel cylinders, I'll assume we're talking four wheel drums and not front discs. I'll also assume you've got a dual reservoir master, and not the early single reservoir unit.
The master cylinder for four wheel drums has residual valves in the MC ports that will generally keep you from being able to gravity bleed the system. In disc brake applications these will only be in the port for the rear drum brakes, not for the front discs. They can be removed, reconnect the lines and gravity bled, and then reinstalled; but that will reintroduce a bit of air into the system again. but you'll get the majority of air out.
There is also an internal transfer port in the dual master cylinders between the front and rear portiions, this generally requires the brake pedal to partially depressed (about an inch or two) to allow the fluid to gravity feed. Block the pedal in position. (This will sometimes allow it to gravity feed even with the residual valves still in place, so try this first.)
Lastly, if it's a front disc system, the proportioning valve may also be blocking flow. If it's a four wheel drum system, it should just be a distribution block and not offer any resistance to gravity flow.
Long story short: Buy a six pack and bribe a buddy to come over and pump the brakes for you. It'll be less horsing around, and it'll be done and over with.
Oh, by the way; if it's got power brakes, bleed them with the engine off. There's the potential for booster damage if done with the engine running.
 
70 bee, all drums, I’m referring to the wheel cylinders as the slaves. That helps me to understand why no fluid is coming out of the master!!
I will try to prop the pedal down a bit and see if I can get some fluid to come out of that master.
 
Shadow said:
Have new master, all new slaves, empty brake lines, everything is dry except for the master which I bench bled and is full of dot 5. Have slave bleed valves open down below.
No fluid will come out of the master.
Do I need to push my brake pedal down and put a wedge in to keep it down? Even when I was mounting the master after bench bleed no fluid was coming out of it before even attaching brake lines.
Click to expand...
If you did a bench bleed and had fluid from front and rear reservoir out of the master then your problem doesn't sound like the master.

I had the same problem once,
It turned out someone pressed the brake pedal to the floor before the old master was removed.
New master bench bled and installed when trying to bleed I got nothing out of the right rear..or any other bleeder.
Everything was clean.
my co-worker (licensed mechanic) said the prop valve was moved with air in the system causing a blockage by the prop valve itself.
I loosened the lines at the prop valve and tapped gently on the brake pedal (NOT PUSHING ALL THE WAY TO THE FLOOR) and started getting fluid.
Something to check even though Its not very common.
 
I did blow out the lines with air to try to clean them before installing all the new parts and didn’t have any restrictions. So I think I’m good there
 
One of a very few jobs I can't do by myself.

I have got them bled enough to drive to friend's hoe by sung a hammer (of all things) and a 4x4 block to wedge the pedal down.

They do make a ratcheting tool...
 
DO NOT BLOCK THE PEDAL DOWN
This will close the Compensating port and fluid CANNOT enter from the reservoir.
If your system will not gravity-bleed, my guess is:
1) the new M/C has still got the lo-pressure hold-back valves installed. or
2) the brake pedal is not parking correctly at the top of it's travel, IE is hung on the brake-switch.
3) that the ports are not open because the pushrod is too long, or not seated in the cup on the end of the M/C piston.
Just pop the cover and look. If you see silver in the port, it is blocked.
Here is a picture to help you envisionchit.
BTW
Yes. many times when you bleed into a container, it will suck the fluid right back in. Many times, I have had to pinch the hose to prevent that. And sometimes I have had to drill the ports a tiny bit larger to encourage the fluid to get moving.
And Yes, the M/C has to be bench bled, with the front end down, to purge the M/C interchamber, which is the chamber between the valves, of air. If this chamber remains full of air, then the rear piston will not hydraulically activate the front piston until the very bottom of the stroke, when the back-up mechanical system engages. That rear piston has to park all the way back to open the ports. On our Mopars, the front piston is pushed back by the associated spring so when the back piston properly parks, so does the front.
Below is a pic of those parts. The little valve thingies to the left of the yellow things are the hold-back valves, usually called residual valves. Only the port to the drum brakes need those. Their job is to keep a lil pressure in the line in an effort to keep the rear cups in contact with the walls of the "slaves" so they cannot relax and seep fluid. Modern design "slaves" do not need them either.
Nd9GcSX7O6LXXZT5ScVW0Fi_M0bYR-PnU8uYXMlCA&usqp=CAU.jpg


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1679340583623.jpeg

Residual valve above. How to get it out below
1679340633829.jpeg

the guts below

1679340195782.jpeg

and the pushrod seated
Nd9GcSOhkVjaW8fgBrmDigPDZEv-E_Qd9u6heq8HA&usqp=CAU.jpg
 
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I’ve got a little play in the top position of the pedal so I’m confident there that All is good with the pushrod. Im thinking #1 from above post is the issue.
As I mentioned before, after bench bleed there was no fluid coming out the ports before even installing the brake lines. It did bench bleed just fine. So the master just won’t leak out any fluid for me to make it happen. I thought maybe pushing the pedal down enough to reposition the pistons in the master might let fluid pass.
 
Last time I did mine. A couple years ago. I took the rear bleeders out and put speed bleeders in. Then I pumped the pedal til I got flow. Then I switched back to regular bleeders and got the wife to pump the pedal while I was at the brakes.
 
I’m thinking going to have the wife come pump the pedal for me to manually bleed, it’s just like Rusty said; going to take a minute or two (or a couple hours lol )
 
I used a pneumatic bleeder because I had to do it by myself. Worked well for me following a complete system replacement.
 
Ya I think I’m beating a dead horse at this point. Luckily I’ve got a pretty patient wife to help me manually bleed
 
My wife once fell asleep in the car while bleeding brakes! "Sweetheart, ok push the pedal down and hold it." (pause, silence) "Did you push it down?" (no response) "Are you ok?" (more silence).

Then we hear Sister Mary Elephant's voice "WAKE UP!!!"

To this day, she HATES to help bleed brakes and bribery of some form is required!! (C'mon, you know I'm not the only one...!!)
 
Not the case here.

Despite only being asked to help 3 or 4 times in over 20 years, she still knows how to pump and hold and say "OK" at the appropriate times without a refresher course.

:thankyou:
 
I just purchased something just like that at autozone. Think I’ll try it first before the wife.
 
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