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Thread: Brake bleeding problem? HELP!

  1. #1
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    Brake bleeding problem? HELP!

    Just completely rebuilt the suspension on '90 XR7. In the process had the calipers/lines and rotors all off. I capped all the lines on the car to keep resivor (sp) from draining. Using all the original brake parts (calipers, pads, rotors, hoses, ect), just painted. Everything worked well/perfect before (MAYBE it took the pump a little longer to reach pressure on first start than when I started driving it a few years ago.

    Now the front calipers won't bleed. I get a first burst of fluid when first opening bleeder, then no flow, key on or off, both sides the same. I can see the pistons/pads moving as helper pumps/holds the pedal. Rears, key on slight application of pedal, good flow no bubbles, clean new fluid. Estimate I've pushed about a pint thru the rears. Pedal is always soft, brake light comes and goes during procedure intermittently, but is off with key on or car running and no activation of pedal. Never get anti-lock light. When key is turned to on position after being off for a while pump cycles properly. If key is turned off for couple minutes, then back on, no pump cycle, so I believe the relay and pressure switch are working, and it builds/holds pressure until the pedal is pressed. Pump comes on every time the pedal is applied at all (light or heavy). Accumulator problem? Could/did it go bad during procedure?

    Only other strange symptom is the firm ride light is always on UNTIL pedal is pumped up and stood on hard and some pressure is built near the floor. As if switch is working backwards (on with no pressure, off when pressure applied). New brake pressure switch from Bill at SCP. Unplug the new switch, firm ride light goes off and stays off til firm ride turned on. Hoping this is a symptom of bleeding problem and will go away once bled out properly. All the Tokiko shock and struts are new.

    Any and all help is appreciated!

    Thanks

    Adam
    Last edited by aroot1; 03-08-2018 at 08:38 PM.

  2. #2
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    How long was the brake system apart?

    Are the calipers installed to the same side they came off of, with the bleeders up?

  3. #3
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    It had been so long that I've bled the fronts, I had forgotten that... unless you have speed bleeder fittings on the front calipers, you need 2 people to do the job.. 1 opens the bleeder screw, the other presses the pedal, guy 1 shuts off the screw before guy 2 lifts the pedal. Then repeat. Run a plastic tube from the bleeder to a catch can or jar, which ever is available to watch the fluid until is is free of air bubbles.

    With speed bleeder screws, there is a check valve built in so you can just open the bleeder and then get in and press the pedal multiple times.

    You can sometimes work around by submerging the open end of the plastic tubing into some brake fluid and raising it above the bleeder, and opening the bleeder. then when you press the pedal, it forces some air out but pulls fluid back in. If you repeat this enough, you can get it mostly clear of air, but it takes a lot of presses. The idea is for the air to travel up as it leaves the bleeder and for fluid to get pulled in when you release the pedal.

    Some people also do a gravity bleed where they simply let it drain, but Im not patient enough for that technique.

  4. #4
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    System was open for couple months in a heated dry shop (life and lots of OT at work got in the way of project). Yes I was careful to put stuff back where it came off, kept it clean, and the bleeders are facing up. I also did everything I could to make sure the reservoir did not drain empty (I never saw level go low due to capping the lines). Only thing I see I could have hurt was I fully collapsed the calipers to paint. Perhaps if there was rust in the bores bad things could have happened, but would expect stuck caliper, not a no bleed (and I CAN see both pistons moving in bores when pumping up)?

    I am USUALLY very proficient at bleeding brakes, even managed to train my wife and daughter on the 2 man procedure (I love 'em, but no small task), my wife was in fact the help in car pumping and holding. I also tried gravity bleeding to start off with, no love. Got the Mity-vac vacuum pump next. No love there either, never got the flow I felt I should have but the bubbles did stop. Then went to 2 person op, still no love. Living in the heart of the rust belt, I have done brake lines and bleeding literally hundreds of times (and at least half a dozen times on THESE cars). Again, USUALLY one of the above methods works.

    It almost behaves like vacuum assist brakes that the master cylinder lost prime and will not draw fluid from the reservoir. Or as if the proportioning valve is only allowing flow to the rear. Thinking about giving it a few gentle-ish taps see if it's stuck, but I believe only 1 front line goes to it so not thinking it'll help.

    I get 4-6 inches of clear, clean fluid flow in the clear hose attached to the bleeder each pump and hold crack the bleeder cycle, no bubbles, but also no more flow. I did not try pumping the brakes with the bleeder open to allow it to pull fluid back in. I will tomorrow. I also have not tried power bleeding by reverse pressurizing at the bleeder (may have to be next step, I do not have one) or pressure bleeding from the reservoir cap (DON'T think that is a good idea with the remote/hose feed to master itself).
    Last edited by aroot1; 03-09-2018 at 02:54 AM.

  5. #5
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    Quote Originally Posted by aroot1 View Post
    I am USUALLY very proficient at bleeding brakes, even managed to train my wife and daughter on the 2 man procedure (I love 'em, but no small task), my wife was in fact the help in car pumping and holding.
    I do them by myself, using a tube that fits on the bleeder that runs to a small bottle with a check valve. Works well. Used that process on all four corners on my Anny.

    Sounds like your process is ok. But fully collapsing used calipers is something I try to avoid. If there is any gunk/rust deeper in the pocket, the puck can hang up when put back in service, raising the kinds of issues you seem to be having. In the past, if I wanted to do something like that, I'd go ahead and tear down the caliper, clean it up and rebuild, but these days, I opt for fresh calipers instead, and just get it over with.

    In these examples, if it's not the calipers, it might be old brake lines that have deteriorated internally, swelling up and creating a restriction that doesn't let the caliper move/contract properly, etc.

    If the master cylinder went dry, you might need to prime it. Search here for discussion.

  6. #6
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    Quote Originally Posted by KMT View Post
    If the master cylinder went dry, you might need to prime it. Search here for discussion.
    That gets my vote.

    I have "bench" bled the master a number of times, usually, whenever I overhaul the motor+pump. Not on an actual bench, but mount in the car, bolt up the lines, then remove 1 at a time, and screw in a plastic fitting (they sell a kit for this), and feed a plastic tube from the outlet back into the reservoir. Then push the pedal many times until the fluid in the tube shows no bubbles. Bolt the line back in place, then proceed to the next one.

    After that, then I bleed the calipers.

    BTW, I think this was covered, but just in case this wasn't discussed, with the rear calipers, you must have the key turned on, otherwise you will get no flow out the rear bleeders. The front calipers do not need the key on. Oh... and still 1 more thing.. the Teves unit must be able to pressurize itself to where the motors shuts off on its own, and brake+antilock lights on the dash turn off.
    Last edited by TbirdSCFan; 03-09-2018 at 02:37 PM.

  7. #7
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    Yeah, I should have known better than to collapse the calipers. BUT I can see them moving as pedal is pumped, so they are not stuck, may not be moving as they should, but seem OK.

    I was unable to find any info on bench bleeding the Teves Mark II. I was not aware they could be done the same as standard master due to accumulator/high pressures. Are they that simple (god knows nothing else on these rigs is )? Any links to procedure if not?

    I also considered the hoses, but they are only about 5 yrs old, I was careful to be gentle with them, and BOTH sides exactly the same at same time? The last made me discount the possibility the most, will revisit that one down the road if nothing else works.

    Did some deeper reading on system function over nite. Now that I have a better understanding of how the system does what it does, I'm beginning to fear its the anti-lock function. Its a 3 fluid circuit with pairs of valves that direct/control FLOW. The inlet/dump valve pairs pulse to limit flow to locked wheel. I'm starting to suspect these valves may be shifted/stuck in position to stop flow to the fronts as if in lock up. NOT GOOD . I DON'T believe my yellow anti-lock light EVER comes on, even during engine start or pressure run up. Maybe never has, never paid much attention, cause life was good. Beginning to suspect previous owner pulled the bulb out of cluster, or has been burned out for a long time. Bottom line, the anti-lock does not work, and I may be facing a new symptom of that.

    I'm heading out to shop now to;

    1 check anti-lock light function
    2 closely inspect wiring, lines ect as I was banging an 18mm wrench around the area doing the upper control arm
    3 tap on the proportioning valve and valve body see if valve might come un stuck
    4 try the hose submerged in bottle of fluid and pumping with bleeders open
    5 "bench" bleed master assy

    Guess if all the above does not produce a little happiness, I'll begin looking into a decent pressure bleeder. Good tool to have, just need a good excuse I guess

    May be time to do another vacuum boost/standard brake conversion
    Last edited by aroot1; 03-09-2018 at 05:40 PM.

  8. #8
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    Quote Originally Posted by aroot1 View Post
    Bottom line, the anti-lock does not work
    Ouch...the hydraulics will operate, but if the pump isn't online, you'd be lucky to stop rolling at all & as noted, it has to be on when bleeding rears.. Is the pedal hard?

    Seen Duffy's SC anti-lock writeup?

    5 yr. old brake lines should be ok.

  9. #9
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    Guess I made that sound a bit worse than I meant it to. The anti-loc FUNCTION does not work, ie it does not cycle the solenoids (pulse) in lock up situation. Probably has no input from wheel sensors . The relays, pressure switch, and pump all worked to give strong brakes, but they DID lock in panic stops now that I think about it. The pump cycles on with first hit of pedal now, may have finally lost accumulator. That could also be air in system allowing pressure to fluctuate. I have a supposedly good accumulator if I ever feel the rest of this is sorted .

    OK, so yesterday I tried the leave the bleeder OPEN while attached to submerged fluid container and......virtually the first pump it belched ALOT of fluid out the top of the reservoir! Made a mess of a bunch o stuff, but I felt it was progress, so pretty happy. Pedal felt a bunch better after repeating the process again, but still not what I'd call "good". Little spongy, and if you stand on it and hold it the pedal slowly (30 seconds-ish?) travels to floor with pump running the whole time, no change with the key off.

    It has improved to the point I'm gonna throw the wheels on it had do a VERY careful test drive up and down the cul-d-sac road next to the house and see what it feels like, put some cycles and heat on everything, try to aggravate any air bubbles to move around to where they can be dealt with. If the pump continues to cycle but all else seems good, I'll do accumulator. If not, I'll try bench bleeding master in place AND accumulator. No love there I guess it's time for standard/vac assist conversion

    Adam
    Last edited by aroot1; 03-12-2018 at 04:10 PM.

  10. #10
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    So, Good news, bad news.... For me anyway. The brakes felt fine on short test drive. Unfortunately, a short test drive with the rear hub nuts not even snugged, or my patented 3 1/2 lb axle removal tool did really unfortunate things to at least the passenger side knuckle bearing . As Led Zepplin would say, "no no no bodys fault but mine"

    Guess those rear bearings for the mustang hub swap for the other car go here instead

    Thanks for the help guys

    Adam

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