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Brake Bleeding Questions - Can't Get Rid of Air

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Old 01-11-03 | 09:59 AM
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Brake Bleeding Questions - Can't Get Rid of Air

Hi,
I attempted to bleed my brakes today. I can't seem to rid my line of air. It is fine, just straight fluid, until the pedal is pushed all the way down, then a little air comes out. I can't seem to get rid of it. I am on the pass rear. There are no leaks on the car. Any suggestions? Would this just mean when breaking do not psh the pedal down all the way? Can I work around it at all? Thanks, Todd
Old 01-11-03 | 10:08 AM
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Don't know what method your using to bleed the brakes. If you're using a rubber hose from bleeder into fluid, or just opening the bleeder, process the same. Pump pedal a few tires, have someone hold pressure on it, open bleeder. Keep pressure on pedal. If going into fluid watch for bubbles, if into air see if any air with fluid. Close bleeder and try again. I forget sequence, but LR,RR,RF,LF. Question is, how did the air get into the system? It's a sealed system. Did you have any of the components apart?
Old 01-11-03 | 10:45 AM
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Your master might be bad... or you might have a leak somewhere
Old 01-11-03 | 10:45 AM
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Also, dont pump the pedal too much or too fast because it will churn up the fluid and you will never get rid of the air.
Old 01-11-03 | 06:59 PM
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Sometimes it is impossible to get all the tiny bubbles out of the brake fluid when bleeding. I recently replaced my Acura's master cylinder, flexible brake lines, and brake fluid. I used a one-man bleeder kit to bleed the lines. Got all the bubbles out that I could tell, tightened the bleed nipples and all, but still had a spongy pedal.


So I just mashed the brakes a few times on the test drive to check that I could still lock up the tires, which I could. I figured it was safe to drive because of this and kept driving it. A day later the sponginess was gone.


I think it was all because when I added new fluid and had it pumping through the master cyl. and lines it got to churning and getting tiny bubbles in it. These bubbles probably slowly rose back up through the lines and into the fluid reservoir on the master cylinder, because now my brakes feel normal. They have a very firm feel when depressing the pedal.
Old 01-11-03 | 09:16 PM
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Originally posted by 88IntegraLS
Sometimes it is impossible to get all the tiny bubbles out of the brake fluid when bleeding. I recently replaced my Acura's master cylinder, flexible brake lines, and brake fluid. I used a one-man bleeder kit to bleed the lines. Got all the bubbles out that I could tell, tightened the bleed nipples and all, but still had a spongy pedal.


So I just mashed the brakes a few times on the test drive to check that I could still lock up the tires, which I could. I figured it was safe to drive because of this and kept driving it. A day later the sponginess was gone.


I think it was all because when I added new fluid and had it pumping through the master cyl. and lines it got to churning and getting tiny bubbles in it. These bubbles probably slowly rose back up through the lines and into the fluid reservoir on the master cylinder, because now my brakes feel normal. They have a very firm feel when depressing the pedal.
Try pressure bledding your braking system.
Old 01-11-03 | 10:55 PM
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you should not push the brake peddle more then 75%. It is possible one of the cylinders in side the master cylinder is not operating properly. The cylinder will sometimes become stuck in the down position from the excessive peddle movement. If this has happened you can try tapping the master cylinder with a hammer to try to free the stuck cylinder.

If you allowed all the fluid to leak from the master cylinder you may have to bleed the master cylinder first.

A simple way to flush or bleed the brake system is, gravity bleed system. Just open all the bleeders and let the fluid drip in a cup, make sure your resivor is full. let them bleed for at least 5-10 min after you see fluid coming from bleeders.

the pressure bleeding system is best.
Old 01-11-03 | 11:39 PM
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Originally posted by scathcart


Try pressure bledding your braking system.

??? Tell me more please, never heard of that method.
Old 01-11-03 | 11:48 PM
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Originally posted by Turbonut
... I forget sequence, but LR,RR,RF,LF. Question is, how did the air get into the system? It's a sealed system. Did you have any of the components apart?
its actually furthest from master cylinder to closest. so RR, LR, RF, LF. i don't know how important that sequence is, but thats what it is.
anyone know what thread size our brake lines are? i wanna try speed bleeders, but don't know what size to get. anyone ever tried em?

i believe pressure bleeding is when they put a device on your brake fluid reservoir and pump the fluid out using pressure. horrible explanation. sorry.

Last edited by casio; 01-11-03 at 11:51 PM.
Old 01-12-03 | 01:54 AM
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Summit racing has the correct speed bleeders, just call them and tell them what you got. They'll might ask you if you have Heavy duty brakes (turbo).
Old 01-12-03 | 06:32 PM
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Originally posted by 88IntegraLS



??? Tell me more please, never heard of that method.
I hacked up a master cylinder cap and put an air fitting onto it, and used an air pressure regulator to send air into the system at 10 psi. Made sure the cap was sealed onto the MC.

It was a little sketchy... the pressure broke the plastic on one MC, but held on another.

Then, bleed by opening the bleeder screw and slowly pushing the pedal down. The presure forces the fluid out, and it can't draw air bubbles back in.

The result is a rock-hard pedal. I had also tried speed bleeders, regular bleeding, and vacuum bleeding, but none of they gave me the feel I wanted.

I got the idea from a car craft magazine where they were using DOT 5 fluid. Pressure bleeding was the only way they could get rid of the spongy feeling associated with silicone brake fluid.
Old 01-12-03 | 06:36 PM
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Sounds good here...

New problem.

I bled the rears fine. But for the fronts, I had replaced the rotor as well as pad. When I unscrewed the rotor originally all the fluid drained out. Now, when I go to bleed it, there is no resistance for the first 2/3 and then u can't push it any further. No fluid comes out. Is this because all the fluid drained out? What should I do? Thanks, Todd
Old 01-12-03 | 06:43 PM
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Originally posted by ToddNappi
Sounds good here...

New problem.

I bled the rears fine. But for the fronts, I had replaced the rotor as well as pad. When I unscrewed the rotor originally all the fluid drained out. Now, when I go to bleed it, there is no resistance for the first 2/3 and then u can't push it any further. No fluid comes out. Is this because all the fluid drained out? What should I do? Thanks, Todd
You should never lose fluid from a rotor or pad swap. Shouldn't even need to remove the brake caliper, or disconnect the line. just move it out of the way, and hang it with some string tied onto your coil.

You need to open the brake bleeder screw, and just pump until fluid comes out. The caliper is empty, and you need to fill it. Then bleed as normal.


You guys are all aware that you bleed your brakes twice, right? Once to get out major bubbles, and then once an hour or so later to get rid of the smaller bubbles that will have joined to form larger ones.
Old 01-12-03 | 06:48 PM
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Originally posted by casio
anyone know what thread size our brake lines are? i wanna try speed bleeders, but don't know what size to get. anyone ever tried em?
They sell them on www.k2rd.com Id assume they would send you the right size, since theyre mostly a Rx7 store.
Old 01-12-03 | 09:04 PM
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if the brakes work at all drive the car a few miles then bleed again. when you drive the air tends to collect at the ends of the lines and makes bleeding easier.

you took the rotor off and fluid came out? how the hell did that happen? either u took off something u shouldnt have or u need a new caliper or line.

pat
Old 01-13-03 | 05:38 PM
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When I unscrewed the caliper apart since it's a two piece caliper, now I realize I didn't have to go that far, but that's what I did. Anyway, pumping the brakes doesn't seem to do a whole lot. Should I have the master cylinder cap open?
Old 01-13-03 | 06:48 PM
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no. leve the cap on. if you cant pump up any pressure u can try just opening the bleeder valve and letting it sit for a while or you can do it this way:
1. open the bleeder valve
2. have someone push the pedal to the floor and hold it there
3. shut the valve
4. let the pedal back up
5. repeat a bunch of times.

this will take forever but it should work

pat
Old 01-18-03 | 08:00 AM
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Is it possible since all the fluid drained out when I took the caliper apart that I need to bench bleed the master cylinder? How can I go about doing that?
Old 01-18-03 | 06:11 PM
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Only possible if you pumped the master cylinder completely empty. To bench bleed, you need connections to hook up to your MC that you can keep some reserve brake fluid in. The problem is with just putting one in without bench bleeding is that when you step on the brakes, it pushes fluid out, and when you let off the brakes, it would draw the fluid back in (and air back in.)

With the lines hooked up into a resevoir full of excess brake fluid (to be sucked back into the lines), just move the master cylinder in and out.

Bench bleeding can be done with the MC in the car.
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