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#1
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Bleeding rear brakes - can't get the air out!!!
I've searched through all the old posts and didn't see anything about a problem like this - I've got a 73 dodge dart sport with disc brakes front and drum brakes rear, manual brakes. Just replaced the master cylinder and both (front) calipers and hoses. The front brakes bled out just fine, and I bench bled the master cylinder with no problem, but the rear brakes just keep coming up with more air (and of course, the brake pedal is spongy and the brake warning light comes on when I press them hard)!
I bleed my brakes with a big jar full of fresh fluid and a plastic tube running from the bleeder screw to the jar. I have a helper press the pedal. I must have put 2 quarts of fluid thru the rear brakes by now! I had gone by the advice of bleed the brakes farthest from the master cylinder first, so I started with the right rear - couldn't get the air out so I went to the left rear. Same there so I went back and forth a while, until I finally did the front brakes (no problem). Still getting a lot of air bubbles coming out of the rear brakes! My helper was saying that even once I opened up the bleeder screw the brake pedal wouldn't go all the way to the floor (like it's supposed to - it did when I bled the front brakes). What's the deal? I read in one post that if the helper presses too quickly it can actually create air bubbles in the lines - how can that be? Thanks in advance for any help!! 3liter 1973 Dodge Dart Sport 1973 Plymouth Satellite |
#2
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sometimes you start
at the master,when it shows clear then the splitter valve with the wire on it and then go to the rear.If it keeps pumping air,its a defective master cylinder.
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#3
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MoparMarc is right. Sometimes you get a stubborn air pocket up front and fluid seems to push past it and so you have to start at the m.cyl.
I did also see a defective m.cyl. cause this once before. Drove me nuts. Finally changed the m.cyl. again and it bled out fine. BTW to get the firmest pedal shut the bleeder just before the pedal hits the floor. Don't let the pedal hit the floor before you shut the bleeder or you loose pressure and suck up a small ammount of air. |
#4
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is your helper holding the pedal down until you close the bleeder screw...if your helper is releasing before,it will suck air back in...
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#5
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Did you bench bleed the master cylinder?
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#6
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Happened to me
The same type of thing happened to me last year with my front calipers on my 73 Charger. After about a Gallon of fluid and two master cylinders I realized that I had installed the calipers on the WRONG side of the car. They fit on either side of the car but putting them on the wrong side puts the bleeder in the wrong position. -- and then you never get the air out.
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#7
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If the guy working the pedal is doing it right, then it sounds like a bad mster cylinder to me or a mis adjustted rod to the master. Best way to bleed brakes is by gravity. Open the bleeders and put a jar under them and keep the master filled. IT should run fluid out of all the bleeders. When it's steady, just start shutting the bleeders off.
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#8
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One other thing possibly overlooked, make double sure your line for the rear brakes is tight where it connects at the mc, and where it splits at the rear axel. These can leak. It's not too likely, but worth checking you have these tight.
also check the tightness of your lines at the prop valve for leaks. |
#9
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Thanks for all the responses guys! I'll bleed the master cylinder over again in the car (gonna use the "two short brake lines curved into the mc reservoirs" method) and then try gravity bleeding (never done that before) and/or ordinary bleeding again. If that doesn't work, I'll replace the master cylinder again and see if that's it.
BTW, I already checked the lines at the master cylinder, the proportioning valve and where it splits off for the rear brakes (on the rear end) - no leaks whatsoever. 3liter 73 Dodge Dart Sport (318) 73 Plymouth Satellite (68 383) |
#10
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Welcome, any time. Hope you find as fix soon.
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#11
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problem solved...
FYI - turns out it was a bad (new) master cylinder - racintracy was right. I tried bleeding the first new mc in the car again, and then gravity bleeding the rear brakes - no dice. So I replaced the mc *again* - that did it - the rear and front brakes bled out just fine. Chalk it up to trusting new parts too much - thanks for all the advice guys.
3liter 73 Dodge Dart Sport (318) 73 Plymouth Satellite Sebring (68 383) |
#12
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bad new parts
I run into this more and more lately,welcome to the world economy.
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#13
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Glad you got it 3litre. Bummer having to do all that unnecessary work though with the defective m/c. Everybody talks about quality control but if you ask me things are sure worse than they were 20-25 yrs. ago. Production numbers take first place. Then if there's any time left they check the quality.
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#14
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Glad you got it fixed. That same thing has happened to me more than once. No quality anymore.
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