Constant bubbles in brake bleeding

infj23

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2003 Saturn Vue
V6
AWD
No ABS

Had to replace a front caliper which was sticking. The heat from operation had turned the brake fluid into nasty, black, thick-looking goo. So, bleeding the whole system to flush out the bad. Right rear bleeding and I keep getting bubbles, some big and some little. Moved to LR, bled fine, old stuff out, brand new stuff in the system with no bubbles ever. RF and LF also bled no problem. Went back to RR, still getting bubbles, some as big as the bleed tubing.

Bad cylinder there? Any other possibilities?

Thanks to all!
Doc
 

infj23

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Thanks Jim. That's what I did. When the bubbles just wouldn't stop out of the right rear, I then moved to LR, RF, and LF. Everything bled great except for RR. Went back to it and still bubbles galore.
 

infj23

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Hello Jim and all,

I tried the bleeding again. LR, RF, RR, RF sequence. At the beginning of the process, LR, still impossible to bleed. I finished the sequence (no problems on the other 3--no air at all), then went back to RR. Still large and small bubbles. It did not seem to matter whether the brakes were pumped 3 times or 1 before I opened the bleed valve, often times the first bubble out was a big one followed by many fine ones. Or sometimes, just a bunch of fine ones. I don't remember any opening of the bleed valve when there were no bubbles. Early in the process, I disconnected the pipe at the cylinder to see if it was somehow misaligned or damaged--everything seemed fine and I reconnected it (then I did the sequence above). Prior to the job, there was no evidence that the cylinder had been leaking. But somehow, air is getting in.

Any ideas?

Thanks again.
 

Ford_Dude

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Make sure that pipe at the master cylinder is good and tight. I recall trying to bench bleed one and it would keep sucking air in. Oh and the bleeding sequence is R/R L/F L/R R/F

Ford_Dude
 

infj23

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Thanks Ford Dude. Just try to tighten down all of the pipes coming out of the master? Or remove/check/clean/replace?

Thanks!
 

NickD

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Suppose to be retired with all kinds of free time on my hands, but didn't get back to my 92 DeVille yet with the same problem. Jim's posted photo bleeding sequence is the same as my manual, and this isn't the first time I had to do brake work on that car. But running into the same problem with constant air bubbles on the RF, #4 on Jim's diagram, does have ABS. I completely redid my brake system in 2003 and have only put about 5,000 miles on the car. Last year, a section of the RR brake line rusted out that works with the LF and suppose to be independent of the opposite diagonal. Repaired that, bled, and got full pedal again. This year the LF line got a pinhole and drained the reservoir dry, replaced that line, but only got a very low pedal.

RF and LR is suppose to be independent of the LF and RR, so I bled the RR, normal, then the LF, nothing but air bubbles, what the heck! But the pedal did come up half way, is as solid as a rock. With a bad MC, would suspect with constant pressure on the pedal, it would leak down if it were bad, but rock solid, car stops rapidly, but just a half pedal. I never ran into this before after some odd 60 years. Are you getting any kind of a pedal?

Besides my motorhome, the only car I can put a trailer hitch on, really never had been driven in salt, and looks almost new yet, so just use it for that. Swear that GM adds some kind of secret chemical to the metal that after a period of time, the brake lines just burst into rust. Wife is suggest we buy a truck, seriously thinking about that, always have junk to haul around someplace. Can't even imagine trying to back up a utility trailer with a motorhome. This car is paid for!
 

infj23

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Thanks, NickD. The pedal feels like it should. Once I replaced the RF caliper, everything felt great. I only went to bleed the others so I could get out the nasty, burnt-looking brake fluid. Except for the dragging of the RF caliper, the system worked fine--I had no reason to suspect a RR problem. So, pedal, even with RR bubbles, feels great. Haven't driven it yet since the caliper job--trying to get it bled--but everything looks and sounds great except for those bubbles. I'm going to put a gentle wrench on the pipes at the MC to see if they need tightening.

Is there any type of sealant/grease/goo that can be put on the threads of the pipes to ensure a good seal?
Is there any reliable and relatively easy way to check the lines to find a possible pin-hole?

Thanks!!!!
 

infj23

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Checked my alldata subscription and found which pipe goes to RR. Put a wrench on that fitting (at the "junction box" below the MC--don't know that thing's real name) and it was tight. Limited leverage there, but I tried to move it tighter and it did not budge.

I presumed that the pipes into the MC and the other pipes on that "junction" were OK because nothing else has bubbles.

Best guess now: likely pinhole or bad connection on a rubber or metal line between the "junction" and the RR cylinder?
 

infj23

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Just spent some time under the car: motor running and my daughter keeping the brake pedal fully depressed. Followed the RR brake line from the wheel cylinder to the MC. No evidence of leaks. Any ideas?
 

jjm

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Try letting gravity do its thing... hook your clear hose up to the RR bleeder, open it, and leave the other end in a container with brake fluid. Raise the front of the vehicle, and give it a couple of pumps and just leave it there for a few hours, or even overnight - but do check the fluid to ensure the master cylinder isn't emptying.

A lot of times it just takes patience. Sometimes it just seems to take endless pumping. After you've used a pressure bleeder, you'll never go back the getting carpal tunnel in your ankles.

Joe

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infj23

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Thanks, Joe. I'll give it a try. Not sure it will work because I've blown about a quart of fluid, maybe more, through that screw, but maybe this will do it.

Questions: should the jar that collects the brake fluid be above the bleed screw and below the master? After it sits overnight, do I then do the standard bleed procedure (pedal down, open/close, pedal up)? The other wheels are fine; do I need to re-bleed them after this?

Finally, what is the right way to dispose of the gallon of waste brake fluid I have collected?

Thanks again to all! What an adventure!

Doc
 

al daniels

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all else fails take it for a drive and see how it stops.if its ok drive it for a while,then rebleed.if there is air causing a problem you will feel it when you hit the pedal.no sealer,by the way,on the threads of the brake lines.its the flare on the end of the line that seals,not the threads.
 

infj23

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Thanks, Al. I drove it and the brakes worked fine. No sponginess. Good stopping on slow, even stops, and good stopping when I hit is pretty hard. All seems well. Just don't like the sight of those big bubbles.
 
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