Bleeding brakes taking forever!!! ???

[VADER]

Hi, I replaced some vacuum brake parts, booster, master cylinder, braided front lines, rotors, pads. I had to reflare the front driver side fitting to the flex line, and used new copper washers on the banjo fittings. I have been bleeding this thing for what seems like forever. I have gone through 2 qts, and 2 pints of fluid, and IM still getting lots of bubbles. I have retightened everything I took apart. The master cylinder was dripping a little, so I tightened it more and it stopped. I had a steel one, and now its aluminum. I had trouble bleeding all the wheels, but figured it was due to cracking it all open. I stopped bleeding the others when I got one or 2 full pedal depressions without bubbles. I do notice that when the pedal is depressed, that bubbles initially come out, then stop, and start again when the pedal is right at the bottom. Really weird. Im thinking I may have reflared wrong, but this shouldnt affect the other wheels, or the steel prop valve that I ignored. I have bled them before without taking it apart, and it was ok then. I also did bench bleed the master cylinder.

 

[suicide six]

Look under dash at pedal area where rod comes thru firwall and see if its wet.

 

[VADER]

Its totally dry under there.

 

[VADER]

If a brake part takes in air, will it also leak fluid? I can probably find it that way. Im almost afraid to tighten things more as if they will strip, or crush.

 

[John Larkin]

I know it's frustrating Danny. You "can" reuse clean fluid and since you've gone through as much as you have, it's undoubtedly clean now. Do a gravity bleed. Just do one wheel at a time, farthest wheel away, then forward in sequence. It's a good Saturday job that will take a few hours. Invariably you get bubbles when you pedal bleed. Also wrap all your bleeders with teflon tape on the threads so they aren't loose when opening/closing. The rears tend to be most loose.

One question: When you depress the pedal, look at the master cylinder with the lid off. Does fluid spurt upward or does it just make tiny bubbles on the surface?

 

[Dabigguy]

I have a really off the wall question. Did you bench bleed the master cylinder?

 

[VADER]

Hey John, how are you doing?

When the pedal is depressed the fluid goes up, if you press too fast it will go right over the side. I still have to clean that up

Yes, I did bench bleed the master cylinder.

What I find weird is that when I am bleeding it, after the pedal is depressed and I tighten the bleeders, bubbles still come out slowly. I dont fully tighten them, but I dont think that should happen. I almost think that when the pedal is pulled up, its taking in air, and Im repeating that over & over. Bleeders dont wear out do they? I think you cant teflon tape the inside of them, but maybe I can on the outside.

 

[John Larkin]

You have an internal leak in your master cylinder. The spurt over the side is a dead giveaway. Check out this article: http://www.babcox.com/editorial/bf/bf60133.htm
That article helped me more than anything. Basically you need to return your master cylinder and get a new one. I got a new NAPA master cylinder for a 87 Regal with a 307 engine, about $75. It ended up being cast iron but I went through 2 remans before buying this one. The reman does not replace the internal valve; it's non-servicable. A new master cylinder will give you a pedal you can hold an easy 12 psi of boost without making this face .

All the teflon tape does is seal the threads around the bleeders so air doesn't get sucked back in past them into the calipers/wheel cylinders. It is good to do.

 

[jhef83]

I'd try bleeding master cylinder again. On car if possible.

 

[VADER]

Update, recvd new master cylinder, bench bled, installed, & system bled easily, about 15 pumps rear (to clean out dirty fluid), and about 5-8 for the front. No more bubbles. Sounds like prop valve occasionally makes a noise, but that might be normal. I'll drive tomorrow to see how it holds up.