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Can't get brake line pressure

Posted By: moposcar

Can't get brake line pressure - 09/09/10 02:15 AM

Guys,
I am trying to bleed the brakes on the 56 Coronet and can't get any line pressure at the brake cylinders (rear) or the calipers (front). The car has front discs from fat man with new master cylinder from tuff stuff I think. I bled the cylinder before hooking the lines up, but for some reason it doesn't put any prssure to the brakes. The discs aren't even pushing against the rotor. What am I missing here? I have fluid to the rotors, and the master cylinder rod is pushed in a few inches when the brake peddle is pushed.

Should I go back and bleed the master cylinder again? I have a summit prop valve and new brake lines as well.

Thanks
Posted By: poorboy

Re: Can't get brake line pressure - 09/09/10 12:49 PM

Where to start....
When you bench bled the master, was it delivering good fluid flow from both ports?
Does the master cylinder return all the way back when the pedal is released? If the master is not returning fully, it can not refill the cylinder because the port is still blocked.
Be sure there are no leaks. The current supply of new fittings, hose connections, and lines don't seem to seat as well as the ones from a couple years ago did, you really need to crank the new ones tight. Recheck every connection, look for even the slightest wetness.
Is all the air out of the lines? These days, bleeding brakes has become a pita.
Unfortunately, these days, "new parts" does not mean the parts are good. Lots of defective new stuff out there.
If all else fails, you will need to check brake pressure at each connection to find out where you are loosing the pressure. Good brake parts will force a finger off the fitting under pressure, if you can seal a fitting with your finger, you have located the problem. You will need to start at the master.
Gene
Posted By: moposcar

Re: Can't get brake line pressure - 09/09/10 01:46 PM

Gene,
Thanks for the reply. I woke up this morning and remembered that the brakes were always spongy. They never hardened up and built up pressure. I don't know if that helps or not.

The bench bleed had good flow coming from the lines, however like you said I had to tighten the crap out of the lines to keep them from leaking and there is a leak somewhere at both new calipers b/c it pealed the paint on them. I was letting them gravity flow out to get fluid in the lines initially and noticed the leaks.

Looks like I have my work cut out.
Posted By: poorboy

Re: Can't get brake line pressure - 09/10/10 02:06 AM

Gotta start by sealing up the leaks. Any tiny leak will give a spongy pedal and/or no pressure.

I'm old enough to remember when a guy could make some money doing brakes, usually quick and easy, but like so much stuff, those days are gone. Gene
Posted By: fstfish66

Re: Can't get brake line pressure - 09/15/10 06:20 AM

is your master cyl on the fire wall or under the floor???

if under the floor,,you need residual valves to hold line pressure since the calipers are now higher then the resoviour,,,( MASTER )
Posted By: moposcar

Re: Can't get brake line pressure - 09/16/10 01:42 PM

My master cylinder is up on the firewall.

I pulled the front wheels off to get a good look at everything, ran down all the leaks, polished the fittings where I had leaks. Then I noticed my bleeder screws on the front discs were on the bottom....I put them there to keep mud/dirt from caking in them. I thought to myself...you dummy, air won't go down to the bottom of a caliper reservoir. So I switched th calipers around to get the bleeder screws on top, and then I really noticed how bad the leaks were. The bolt with the brass washers that threads into the calipers was leaking. I tightend the shiznit out of them and they still leaked.

So when the car went to the front end alignment shop, I asked him to finish them for me. Tired of beating my head on it and have too many other projects to finish.

Thanks for all the replies. Figured you guys would like to hear about the bleeder screws on bottom...the little things sometimes.
Posted By: fstfish66

Re: Can't get brake line pressure - 09/16/10 02:57 PM

usually,,those brass washers on the calipers cant be reused,,,and most require 2 washers one on each side of the hose fitting,,,

so it would be bolt,washer,hose end,washer in to caliper,,, let us know how you made out
Posted By: Supercuda

Re: Can't get brake line pressure - 09/17/10 11:08 PM

I've noticed that reman calipers come with new washers that are too thin to work, the rifle drilled bolt bottoms out well before the washers seal. PepBoys used to carry a selection of copper sealing washers.
Posted By: rowin4

Re: Can't get brake line pressure - 09/18/10 09:22 PM

Don't feel to bad about putting the calipers on the wrong side [ bleeder on the bottom ] seen it on here a number of times, your right , it's hard to bleed the air out down. Normally need to get new washers each time there removed, most auto parts stores have them.


Posted By: bigdad

Re: Can't get brake line pressure - 09/18/10 11:51 PM

I would like to see pics of the car ?

Whats the chance of that ?
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