Can't bleed brakes
 

So Ive been doing some brake work. Had trouble bleeding so I filled up the master cylinder to full. I left the master cylinder cap off over night with all the bleeder screws removed, on all four wheels. Checked on it this morning and the master cylinder was still completely full both front and rear. Prop valve would shut off one side but not both so that can't be it. Why won't this thing drain?

Disc front drum rear. New soft brake lines.

Re: Can't bleed brakes
 

What about getting a second person to do the brake pedal while you go to each wheel cylinder to bleed? That's worked quite well for me in the past with my daughter's help.

Re: Can't bleed brakes
 

Sounds like your MC crapped out. This happened to my buddys El Camino. I had to replace the MC and they bled like a charm.

Re: Can't bleed brakes
 

How does this indicate that my Master Cylinder crapped out? I would like to understand. It is not being functional it is just standing stationary holding fluid in it.

Re: Can't bleed brakes
 

Are your calipers and bleeders new? If they're old remove the bleeders and clean out the passage. I've had four plugged up at once before.

Re: Can't bleed brakes
 

Bleeders are removed. I unscrewed them completely and set them in brake cleaning solution. To answer the question specifically, the calipers are less than a year old. both rear wheel cylinders are new within the last week.

Re: Can't bleed brakes
 

It's supposed to pump fluid to the calipers and or wheel cylinders. If it's not moving fluid and not building pressure then something is wrong.

Re: Can't bleed brakes
 

My question was regarding gravity bleeding which, if I understand correctly, has no need for a master cylinder to be mechanically functional. Gravity should pull fluid from an upper location (the master cylinder) through a lower location (the open bleeder valve).

Re: Can't bleed brakes
 

Ive heard that gravity bleeding wont work if you have air trapped in the system.

Re: Can't bleed brakes
 

it should move some fluid. i would say you have a block some where.try having some one push down and see what you get out of each one.

Re: Can't bleed brakes
 

Make sure there is some free-play at the pedal. If the pedal is pushing in on the piston, it will close off the fill ports in the m/c.

Re: Can't bleed brakes
 

The question: Would the air in the line be enough to prevent gravity bleeding on the front wheels?


The back story:
ok, so I let the truck sit with the bleeders removed from the back wheels for 48 hours and got some fluid. I feel good about this. I then filled the MC (it was about 25% full). Now i have confirmed that I can put fluid in the Master Cylinder and get that same fluid out of the rear bleeder.


My front bleeders are now open and no fluid has moved through them. Car has been sitting about 5 days with cap off the MC and front wheel bleeders completely removed. The MC is full to the brim with brand new brake fluid. I have confirmed there is nothing clogging the master cylinder.

Would the air in the line be enough to prevent gravity bleeding on the front wheels?

Re: Can't bleed brakes
 

Why not get a second person on the pedal and bleed the brakes that way??? Push the air bubble out and you should be ready to go in 30 minutes....

Re: Can't bleed brakes
 

I could see that happening. Air wanting to go up, fluid trying to go down, getting a little jam there that gravity can't fix. But like Ski-me said, nothing a second person couldn't fix quick. Don't forget the fluid is hydromorphic and will absorb water out of the air.

Re: Can't bleed brakes
 

Just give that pedal a light push and let it up slowly go look at fronts. I would close the back ones and set the cap on the M/C as you do this.

Re: Can't bleed brakes
 

I'm going to give it a shot this weekend. I'll let you know the results. I've had a hell of a problem with these brakes. I did bleed extensively bleed the master cylinder.

Re: Can't bleed brakes
 

Sometime gravity bleeding works for me and some times it doesn't. Never really figured out why. I tried to gravity bleed mine a couple months ago and left the bleeders open overnight and nothing came out. I couldn't wait forever so I used a Mightyvac to pull it through. I know you probably don't want to buy another tool just to get this job done but they do come in handy for other things once in a while.

Re: Can't bleed brakes
 

vaccum pums are great. hydro clutchs it helps with too. i have used them on a lot of things good to have around. once you have it you will use it more then you think

Re: Can't bleed brakes
 

This won't work properly. You need to do each wheel independtly otherwise you won't get a proper bleed.

There is a reason why they say to bleed each wheel on its own. If gravity bleeding is too slow pick up a vacuum bleeder which takes one person and goes much faster.

Re: Can't bleed brakes
 

I've never had good luck with Mityvac.
You can DIY a pressure bleeder like the Mercedes Source or Motive and buy or fab the master cylinder caps. Most of the cost of my pressure pot is the Motive MC caps...
A 2 liter soda bottle will work as a catch can with some short clear hose that fits tight over the bleeder.
http://www.amazon.com/Motive-Products-105-System-B...
Video embed has stopped working for me???....
pressure bleeder youtube video

Re: Can't bleed brakes
 

This device: http://www.princessauto.com/en/detai...it/A-p8050832e

Re: Can't bleed brakes
 

How old are your rubber flex hoses ?
Even if there look good on the outside they can deteriorate on the inside and plug up.

Re: Can't bleed brakes
 

Ok. Here's where I am. Had my wife press the pedal while I operated the bleeder. I went Right rear, left rear, right front , left front. I clamped the button on the combination (proportioning) valve. I got excellent flow from the front bleeders and poor from the rear bleeders. I Cycled about 1/2 a quart of fluid through each front caliper. I didn't move much fluid through the rears regardless of the time spent on each rear wheel. The pedal is still very soft and must be pressed to the floor to apply any braking power. The rear brake shoes have been snugged up to the brake drums.

The combination valve is tripped(brake warning light is on). Is there a way to reset it without opening the front bleeders? (Kicking the pedal has not been successful for me in any speed, repetition combinations).

Re: Can't bleed brakes
 

far as i know have the wife go ez and crack a bleed and watch the light as soon as its off close the bleeder.

Re: Can't bleed brakes
 

Crake the rear or front bleeders? (I assume front but would like confrimation)