Bleed the brakes

[Belgium R/T -68]

Well, gravity doesn't seems to excist in my car. There is some oil coming out of the bleeders on the calipers but it's like it's just
standing still. Is that a sign that the mastercylinder isn't correct bleeded? If I use my pump all I get is airbubbles.

Per

[maxwellwedge]

When you bled the master only does it pump fluid? Did you keep bleeding until no more air bubbles.
If everything there checked out you could have a plugged line(s), metering block or hoses.
Assuming the master is properly bled - Go backwards from the brakes to hose to metering block until you get fluid. That will pinpoint your problem.

[b5blue]

I know what you mean my car sat with dry lines for a few years while I worked on what I could and I had one hell of a time getting all the air out. I ended up getting a compressed air driven "vacuum bleeder" from harbor freight (everyone else wanted 100's of dollars for one) and at that I still had to take the thing apart to max out operation. I think the best kind would be the ones that push fluid through the master but they were $$$ and I knew nobody to barrow one.   

[Belgium R/T -68]

Wait a second, for letting gravity do the bleeding, does the pedal needs to be in down position?

Per

[b5blue]

UP! And the top off the master.

[Belgium R/T -68]

What about using a vacuumcleaner as a pump? Much moore power then the litle handpump I have.

Per

[dpixel]

What I've heard is gravity bleeding is the best way because pumping the pedal can break up the big bubbles into small ones that are harder to bleed out.  You can watch the bubbles at the bleeder screws as they are pushed out.  

[b5blue]

Shop vac I never thought of.......for me it was having the vacuum lasting more than 20 seconds so yes try it. Gravity counts on the fluid that is in there pulling more in behind it so it has to at least have some to start working.

[Belgium R/T -68]

Stopped by a small garage on the way home and the old man had a "machine" that push the oil in from the bleeders. He told me to attach
it to rr and keep the pedal down until the oil starts to come up in the reservoar. Worth a try, I think you mentioned something about this
way B5blue?

[b5blue]

Well that's backwards but anything to get the lines full, too bad you didn't have it sooner!  hook that puppy up and let's see...good luck!

[Belgium R/T -68]

Doesn't work The oil is not pushed into the lines, it's like the ports to the mastercylinder closes when the pedal hits the floor.
From calipers in front the oil is now flooding nice without airbubbles but that stupid pedal still hits the floor and from the rear bleeders
nothing comes out.

Per

[FLG]

Per,

Did you bleed the master by itself??

http://www.superchevy.com/technical/chassis/brakes/0509sc_bench/index.html

[lisiecki1]

what about disconnecting the rear lines at the proportioning valve and gravity bleeding from there and then connecting them back to the proportioning valve and bleeding normally?

[Belgium R/T -68]

FLG, I did one circuit at the time. Is there a difference by doing them both at the same time like the article describes?

Randy, there is only coming oil from the m-c when the pedal is at the floor so the gravitybleeding mentioned here doesn't work for me.

Per

[lisiecki1]

what i was saying would take the master cylinder out of the equation and let you get the lines full and possible bleed normally after you get them filled up.  This is kinda shade-tree tech, but, unhook the rear lines from the proportioning valve and get a sandwich bag and put a hole in it so you can get it over the end of the line and rubber-band it on there tightly.  put an unwound coat hanger through the top of the bag to hold it to something (hood, etc.) and fill the bag with brake fluid and let it sit.....remove the bleeders completely from the rear cylinders and connect a hose to the holes to keep from getting the backs of the drums nasty...once the bag is close to empty, replace the bleeders and remove the bag and reconnect the lines to the proportioning valve.  Yes it's messy, but I've done it before and it worked to gravity bleed/fill the lines.  I don't know if it will solve your ultimate problem, but the lines will be full.

Side note: are you sure there's nothing wrong with the proportioning valve to begin with?  It's my understanding that most valves have a failsafe that cuts the rear end out of the equation in the event of a pressure loss, so you'll still have some kind of braking ability....

[oestermarken]

I don't think you can push fluid backwards in the system with the pedal down. When the the pedal is pressed down the return ports in the master cylinder will be closed, otherwise you will loose brake power with the pedal down under normal use. Make sure your master cylinder piston are moving all the way back when the pedal is in top position. Make sure that fluid runs out of both master cylinder ports with no brake lines mounted and the pedal in top position. Take it from there

[Belgium R/T -68]

Well, maybe it's time for some basic lessons about the brakesystem for me. To start with, under normal curcomstances with a filled system,
should it come oil out of the ports of the mastercylinder if the pedal isn't pressed down? The pedal, when I say pedal to the floor, do you guys then
say it's up or down? The system and the m-c has 2 circuits so pure teoretical if you could bleed for example the front system you should have
working front brakes but no oil/brakes in the rear or are they still connected?

Per

[b5blue]

Down means the pedal is depressed to the floor board. I'm going to be installing my new master today. I started to yesterday but after plugging the lines in the side with the supplied plugs and dumping fluid in there, then pumping like hell, I can tell that will never get rid of all the "air bubbles". (like the instructions imply) So after looking for my "master cylinder bleeding set" for about an hour I gave up, went out and bought a new one. It just came to me that if you have a pressure adjuster installed to the rear lines make sure it is open all the way for bleeding. My thinking is you have air in the master cylinder still somehow.

[Belgium R/T -68]

What about front and rear circuit, are they connected?

Per

[b5blue]

I'll check my book today (as I redo my car) but I'm fairly certain they are completely separate as a safety feature. 

[Belgium R/T -68]

I'll check my book today (as I redo my car) but I'm fairly certain they are completely separate as a safety feature. 

Thanks, another question. Is the brake hold off valve keeping me from filling the rear system with oil from the rear bleeders?
Meaning is it a one way valve?

Per

[b5blue]

Well that's what I was wondering. My car is a Drum brake car so I'll have to add a restriction valve to the rear when I convert to front disk. Your car should have one if it has front disk. It may be in the proportioning block if your car came with disks new, I don't know.  It would seem to fit your problem but mine were a pain in the butt without one. I thought OK if you added one did you open it up or could it be shut off stopping the fluid? Keep in mind my car had me messed up for days, I could not get fluid to run to the rear using all the old tricks. I found they make tools to force fluid through the master, and tools to suck it through the bleeders but they were all 200.00 or more at parts shops. I found a cheap (25.00) one at Harbor Freight and used it. Even then I had to remove a restrictive part from it and let it run quite some time before it got fluid all the way back. I know my problem was A: bone dry lines and wheel cylinders B: Not wanting to spend 250.00 to use a tool 1 time! 

[Belgium R/T -68]

Found a small leak at the distributionblock, to right front. Opened up at hold off valve but there was desert dry, never been oil there so
I will go back to m-c. The pedal needs 10 minutes to go back up, is that a clue for something?

Per

[Belgium R/T -68]

Made some progress tonight Bleeded the rear side m-c and it was full of air, then I disconnected the hold off valve at
the side towards the distrblock and could press in oil from rr bleeder untill it came out at the valve so now at least the system should be
almost full with oil. I think I have moore response in the pedal, meaning I can build up some pressure.
Tomorrow I will start the normal bleeding routine and hopefully it works.

Per

[b5blue]

  Now it will gravity bleed!