HELP! bleeding brakes, accidentally let master cylinder run DRY! Now what?!?

[gary_g]

Okay, I was installing a cobra brake conversion, and when I was bleeding the brake system, I accidentally let the master cylinder run dry. Now the brake pedal requires little to no pressure to press it down. I tested the brakes by rotating the front and rear wheels and then pressing the brake pedal and it did stop the wheel from spinning, but I'm pretty sure that it wont stop me if I'm driving down the road.

The Haynes manual I have says that if this happens, you need a "very expensive tool" to bleed the brake system, and leaves it at that.

Does anyone know what I can do? Other than towing it somewhere?

Thanks,

-g

 

[Screwed2V]

You do in fact need to bleed the brakes now. No way around it.

 

[Snarf]

The 'very expensive tool' is an automotive brake bleeder, approx 60 bucks. Its not the end of the world just a tiem consuming thing to fix. No way around this, and I would reccomend you doing it yourself. Its real easy, and a ford shop will no doubt screw ya over to do it.

 

[gary_g]

I hate to ask a stupid question, but what does an automotive brake bleeder do differently than bleeding the brakes manually with a cup and a rubber hose? I was actually finishing up bleeding the brakes manually when I let the cylinder run dry. After refilling the master cylinder I tried re-bleeding all of the brakes, but the brake pedal is still soft.

The automotive brake bleeder will fix that?

Thanks!

-g

 

[gary_g]

I hate to ask a stupid question, but what does an automotive brake bleeder do differently than bleeding the brakes manually with a cup and a rubber hose? I was actually finishing up bleeding the brakes manually when I let the cylinder run dry. After refilling the master cylinder I tried re-bleeding all of the brakes, but the brake pedal is still soft.

The automotive brake bleeder will fix that?

Thanks!

-g

Also, is this what I need?

http://www.automotive-brake-tools.com/automobile-brake-bleeder.htm

 

[bdcardinal]

you probably have to bleed the master cylinder. get someone to help you with it and bleed the lines as you would bleeding at the wheels. you will probably have to go ahead and bleed the brakes again, just make sure to keep the cylinder topped up.

 

[Snarf]

The differnce betewwen using the vacuum pump [auto bleeder] and doing it manually [hose and bottle] is gravity.

Doign it manually is also called gravity fed bleeding. it will get some of the smaller air bubbles and stuff. It works just fine if your line systems is like 99% purged of air.

You'll need more pressure to force all of the hard-to-reach bubbles out. There are high spots in the stock brake routing that can trap air, and you'll need significantly more oomph than what just gravity bleeding can give you.

Also, this Mityvac system [ http://www.automotive-brake-tools.com/automobile-brake-bleeder.htm ] is the exact bleeder I have in my garage right now. Works like a charm! Hope this helps man.

 

[gary_g]

Okay, I'm totally lost.

I bought the Mityvac Automotive Vacuum system, and I'm still having trouble.

When I try to vacuum bleed the brakes at the calipers, it's just non-stop bubbles. In the manual for the Mityvac system, it says to first bleed the master cylinder before bleeding the brakes themself. I checked in the Haynes manual, and it says in order to bleed the master cylinder you must do the following:

Have an assistant depress the brake pedal. While the brake pedal is depressed, open the bleeder valve on the master cylinder and allow air/fluid to escape. Tighten valve and have assistant remove pressure from the brake pedal. Repeat this process until no air escapes when opening the bleeder valve, then repeat this process on the other bleeder valve on the master cylinder (I guess these are front and back?).

Anyhow...

I did all that, and that went okay. I then attempted to bleed the brakes, and it's STILL nothing but air bubbles. I spent 15 minutes pumping on the same brake, and all it did was suck a fluid/air mixture until it filled up the resevoir on the Mityvac pump.



HELP PLEASE!


I'm pretty sure my friend is getting sick of helping me by now, and I *NEED* to make it to work tomorrow.

Thanks,

-g

 

[gary_g]

Okay, well, here's what (in my infinitely finite wisdom) I decided to do...

After bleeding the master cylinder by pressing/releasing the brake while opening and closing the bleeder valve, I noticed that the pedal seemed to firm up a bit. Not 100% firm, but better than it was before... So, I then tried to bleed the brakes using the vacuum pump, and it was steady bubbles... Since I had already bleed the system at the master cylinder, I decided to try a standard gravity bleed again just for kicks.

Much to my (and my helps) surprise, it spat out bubbles for a few whacks on the brake pedal, and then went to 100% bubble free fluid out of the bleeder valve. I repeated this on all four calipers, and decided that I might as well go for a spin around the block.

Doh!

So after a few near-death experiences, it became immediately apparent that the brakes WERE NOT working correctly. The brakes did stop me, but only after a VERY long slow-down process, which felt almost like brake fade.. ?

So anyways here I sit, stranded at my mothers house where I was doing the install.

Anyone have any ideas? So far everyone I spoke to told me to "take it to a dealer". Is there anything else I should try on my own first? I'm pretty broke, so saving money would be a good thing at this point.

Thanks!

-g

 

[drb81]

bench bleed your master then bleed all four calipers

 

[Boyd Hamilton]

where can i purchase a vacum pump because i ran master dry i will be working by myself

 

[Mustang5L5]

There are two bleeder ports on the side of the master cylinder. Hook these up to a hose and put the end in a bottle. Have a friend pump the pedal while you crack one bleeder at a time.

That should bleed the MC of all air.

 

[NXcoupe]

Problem is, it sucks air around the threads of the bleeder since it's loose. Best way to fix your issue is buy a rubber expansion plug from the auto parts store that will fit into the opening of your master cylinder reservoir, then drill a hole thru it large enough for you to force a piece of 3/16" brake line thru the hole. Let it protrude about 1/8 of an inch out the bottom and a couple inches on the top. Slip the hose from your mighty vac over the longer top part of the line and secure with a small hose clamp. Insert the plug into the mc fill opening and use a wrench to snug it in. Then pump and apply vacuum. It helps if you pump the pedal some while under vacuum. Repeat a few times until the pedal is very firm with no vacuum applied.
This setup cost me less than 10 bucks and I use it on hydraulic clutches and hard to bleed brake system. Your problem is with the master cylinder mounted it is at an upward angle and the air rises to the top and won't come out except under vacuum or sitting horizontally.

Sorry for the long post, just trying to help