1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Air keeps coming out while brake bleeding

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Old 02-12-09, 11:03 PM
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Air keeps coming out while brake bleeding

Well, I thought I had a leaking brake line on the passenger side front wheel. I changed it out with another one. Go to bleed it. Air bubbles just keep coming out. No leaks as far as I can tell in the front, including brake master. I know for a fact there are no leaks in the rear. I'll go double check the front and master in a liitle. What would cause air to keep coming out though? Seized caliper, bad master that is leaking internally? I just finished my front brakes and suspension and i can't go out for a joy ride
Old 02-12-09, 11:18 PM
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If you turn your bleeder screw too far out it will appear as though air bubbles are coming out from inside but it just air going past the threads. Tighten everything back up and press on the brake pedal. If you have a spongy brake pedal then you still have air in the system. If the pedal feels nice and hard like my....... on a Saturday night then you are good to go.
Old 02-12-09, 11:27 PM
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Originally Posted by ultimatejay
If you turn your bleeder screw too far out it will appear as though air bubbles are coming out from inside but it just air going past the threads. Tighten everything back up and press on the brake pedal. If you have a spongy brake pedal then you still have air in the system. If the pedal feels nice and hard like my....... on a Saturday night then you are good to go.
alright. I'll go do it again and see whats up. Thanks.
Old 02-13-09, 12:22 AM
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You can also put a thin layer of lithium grease around the outside of the thread/caliper junction point; this will prevent air from bypassing the threads on the bleeder, and has the added benefit of making it easier to undo next time.
Old 02-13-09, 12:23 AM
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how are you bleeding the system? do you have someone pump the pedal and hold it while you open the bleeder? or are you using a vacuum bleeder? if your using a vacuum bleeder and you tighten the bleeder screw down immediately, as soon as you open it up again a couple bubbles will always seem to pop out.

whenever i replace a section of the brake system i always let it gravity bleed for sevral minutes before i even bother w/ the final bleeding at each corner. also when i use my vacuum bleeder i like to let the bleeder screw stay open and gravity bleede a couple of drips before i tighten it back down, just to ensure that air didnt some how find its way back in.
Old 02-13-09, 12:58 AM
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You can also put a thin layer of lithium grease around the outside of the thread/caliper junction point; this will prevent air from bypassing the threads on the bleeder, and has the added benefit of making it easier to undo next time.
Thanks for the tip. I'll try that.

Sgt.Stinkfist how are you bleeding the system? do you have someone pump the pedal and hold it while you open the bleeder? or are you using a vacuum bleeder? if your using a vacuum bleeder and you tighten the bleeder screw down immediately, as soon as you open it up again a couple bubbles will always seem to pop out.

whenever i replace a section of the brake system i always let it gravity bleed for sevral minutes before i even bother w/ the final bleeding at each corner. also when i use my vacuum bleeder i like to let the bleeder screw stay open and gravity bleede a couple of drips before i tighten it back down, just to ensure that air didnt some how find its way back in.

Ya, I got a vacuum bleeder.
Old 02-13-09, 02:40 AM
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Well I just got done rebleeding it and I had no air bubbles. Get everything back together and get ready to go test it. Start the car, press the brake and drops to the floor. Go to look at the master cylinder and see brake fluid slowly running down the booster. Guess new master is on its way.
Old 02-13-09, 09:10 AM
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that sucks. make sure you thuroughly bench bleed the master before you put it on your car. just go slow and get all the bubbles out. hope everything works out for you.
Old 02-13-09, 09:19 AM
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bleed at each wheel in this order until the fluid runs clear and no bubbles are coming out:
RR, LR, RF, LF
Old 02-13-09, 01:01 PM
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Originally Posted by DivinDriver
You can also put a thin layer of lithium grease around the outside of the thread/caliper junction point; this will prevent air from bypassing the threads on the bleeder, and has the added benefit of making it easier to undo next time.
Very good tip, I'll make use of that next time I have to bleed brakes.
Old 02-13-09, 06:50 PM
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Ya this does suck. I still need to go get the master, I just woke up . Do I really need to bleed them at every corner? I'll let you guys know what happens after I get it installed.
Old 02-13-09, 08:22 PM
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if you replace the master cylinder , then yes, you have to re-bleed each corner
Old 02-13-09, 08:41 PM
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Yes, definatly bleed every corner.
Old 02-13-09, 09:29 PM
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and not that it requires it but when replacing hte brake master cylinder, bench bleeding is a benifit and makes overall bleeding much eaiser. i bleed the brakes in all of my cars once every two years. i bleed until clean fluid comes out of each bleeder. makes me feel better if anything
Old 02-14-09, 12:53 AM
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Originally Posted by mazdaverx713b
and not that it requires it but when replacing hte brake master cylinder, bench bleeding is a benifit and makes overall bleeding much eaiser. i bleed the brakes in all of my cars once every two years. i bleed until clean fluid comes out of each bleeder. makes me feel better if anything
Me, too. Brake fluid is hydrophilic; it absorbs water over time, which makes it "compressible" and dramatically lowers its boiling point. Changing it out entirely every few years is just good practice.
Old 02-14-09, 10:22 AM
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Originally Posted by mazdaverx713b
and not that it requires it but when replacing hte brake master cylinder, bench bleeding is a benifit and makes overall bleeding much eaiser. i bleed the brakes in all of my cars once every two years. i bleed until clean fluid comes out of each bleeder. makes me feel better if anything
um actually if you read the directions on any mastercylinder it says to bench bleed it. if you dont you will never get all the air out. believe me i do this for a living.
Old 02-14-09, 04:20 PM
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perhaps you're right. i've never not done it...
Old 02-14-09, 04:50 PM
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what you can do when you install your new MC, is to crack all the lines that you snug up to the NEW MC once you have bench bled properly. Air is going to move to the highest point in a gravity bleed, so let all the lines drip a little and they will purge the air out. Then have someone pump the pedal ONCE. You've got ONE shot to remove the remaining air at the top of those lines and between the MC before the bubbles get pushed farther down.

Or you can bleed the whole system again...
Old 02-14-09, 06:03 PM
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Installed new master just now. About to go bleed every corner.
Old 02-14-09, 06:50 PM
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Well another problem now. I go to bleed the brakes. Press the pedal halfway, then from there it falls to the floor. I take off the MC and I can pull like this rod out of the brake booster. Did that take a **** on me now? I'm about to roll my car off a cliff this is pissing me off.
Old 02-15-09, 08:26 AM
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that rod is what pushes the master cylinder when you press your brake pedal.. did you check your linkage under the dash? maybe the problem is there.
Old 02-15-09, 09:33 AM
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That rod that goes through the booster really isn't held in by anything, it can move around if things are appart. Maybe when you had the master cyl off it came out of alignment or something. Hard to explain, but it should slide into place.
As for bench bleeding, I've never bench bled a MC and it always works fine for me.... strange..
Old 02-16-09, 04:16 AM
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Well everything is good now. Got her back on the road. Thanks guys
Old 02-18-09, 10:22 AM
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Thats good to hear your brake troubles have been resolved as I was not so fortunate and needed a brake booster (which I believe rarely fail) which I didn't think was the culprit of my strange brake pedal feel. Leaking brake fluid from the rear seal on the MC leaked into the booster causing damage to the diaphragm inside.
Old 02-18-09, 12:25 PM
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Brake fluid is quite destructive stuff; eats paint, eats many types of rubber, and once it becomes hydrated with water it promotes rust and attacks aluminum...

But it makes a great hand pre-cleaner! It'll get off many types of paint, glue, grease... and then it washes off easily with regular hand cleaner.


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