Vacuum brake bleed question

Discussion in 'General Automotive Questions' started by Clark, Aug 16, 2018.

  1. Clark

    Clark In Maximum Overdrive

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    Following the detailed write up on another website, I replaced the rear drum brakes on my '02 Ford Ranger with a disc brake setup using '02 Mustang GT equipment. As per usual, this one day upgrade required three days to complete though without the usual blood sacrifice (did exhaust my extensive list of expletives).

    I had lots and lots of problems attempting to vacuum bleed these rear brakes. Turned out there was a ding in these O'Reilley rebuilt calipers where the banjo bolt and copper washers seat on the caliper resulting in an air leak. Sheeez!

    Even after fixing the caliper (filed it smooth), I continue to draw air bubbles when vacuum bleeding. I always loop the vinyl tube up and over so I can view any bubbles pulling through the brake fluid. There is no real brake fluid extraction but lots of air bubbles. The brake pedal is solid and the stopping power is better than ever but what's with the bubbles?

    First I found that I was drawing bubbles even with the brake bleeder fully closed - sheez. So I put a clamp around the vinyl hose over the brake bleeder nipple which stopped that.

    Even so, I continue to draw bubbles until the bleeder valve is clamped tight. I'm thinking I'm pulling air in around the threads of the bleeder valve though I've never had this problem in the past.

    Anyone else ever run into this?
     
  2. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    Skip the vacuum and do a gravity bleed. Make sure the reservoir cap is loose.
    Modern brakes are hard to bleed with a vacuum bleeder, you need a reservoir mount pressure bleeder.
    Wasn't there a residual pressure valve on your drum brakes? If so, did you remove it?
     
  3. 1965 Ranchero 66G

    1965 Ranchero 66G In Maximum Overdrive PLATINUM MEMBER

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    I'm still a firm believer of self bleeders.
     
  4. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    All forms of pump bleeding risk safety features in modern braking systems blocking fluid to a braking circuit, often not automatically resetting.
     
  5. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    The original seal surface on the caliper is supposed to have two or three rings to crush the copper washer against the smooth underside of the banjo bolt. Even if it's recut just a few degrees off, it can cause an air leak, but those rings need to be there to crush the washer properly. I would've taken it back, got another, and do it as many times as you have to in order to get a good seal there. As for the follow-on air leaks, the threads of the bleeder can allow air through, which means the system does not have any air in it.
     
  6. Clark

    Clark In Maximum Overdrive

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    Yeah, I would've taken it back BUT the local O'Reilley's didn't keep them in stock. It also becomes a real pain swapping those calipers. Also have nosey neighbors and frigg'n HOA rules to contend with here.
     
  7. Jimbob

    Jimbob SITE SUPPORTER- SILVER GOLD MEMBER

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    With vacuum bleeding, you were probably sucking air through the bleed screw threads. Also, what type of brake system was it? I had a 90s Mark Lincoln, where to bleed the rear brakes you just held the pedal down until it ran free of bubbles, no pumping.
     
  8. 1978GT

    1978GT In Fourth Gear GOLD MEMBER

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    X2 on gravity bleed. Simple and effective.
     
  9. TestDummy

    TestDummy In Maximum Overdrive SILVER MEMBER

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    Gravity feed doesn't work on newer cars. The fluid will not flow through the ABS module on its own.
     
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  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    For the ABS module, whether you gravity, pressure or vacuum bleed them, you need a scan tool to exercise the solenoids. After that, then you can gravity, pressure or vacuum bleed them.
     
    Last edited: Aug 18, 2018
  11. Jimbob

    Jimbob SITE SUPPORTER- SILVER GOLD MEMBER

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    Or a dirt road!
     
  12. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    I'd pay a dollar to see you try that!
     
  13. Jimbob

    Jimbob SITE SUPPORTER- SILVER GOLD MEMBER

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    It's easy:
    1. Bleed the brakes.
    2. Find your dirt road.
    3. Get up to a decent speed, and slam the brakes on, to activate ABS.
    4. Repeat step 3 a couple of times.
    5. Rebleed the brakes.

    I will admit, I have not yet had to do this. I have a scan tool that does it. But this can be done, I did a lot of research into it as my '97 C1500 needs this procedure., this is apparently how they do it.
     
  14. 1965 Ranchero 66G

    1965 Ranchero 66G In Maximum Overdrive PLATINUM MEMBER

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    And who doesn't like playing in the dirt with their car and its the best excuse to the wife, hey honey I need to fix the brakes on the car.
     
  15. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Well, you see, it's not watching you pump the brake pedal as you chogey down the dirt road, it's watching you careen into a mesquite tree when the brakes fail to stop you on that curve....:eek:
     
  16. plumcolr

    plumcolr In Maximum Overdrive

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    My technique is similar (for a 97 Suburban K1500) except I keep one side on asphalt, the other on gravel / sand so the ABS engages. Then rebleed.
    10 - 15 mph is more than adequate.

    Sometimes needed to do twice. Thing is notorious for leaky rear wheel cylinders, various brands. And because of the ABS / combination valve will not vacuum bleed. Disk/drum combinations suck.
     
  17. Jimbob

    Jimbob SITE SUPPORTER- SILVER GOLD MEMBER

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    I have a Tech2 Scanner, but apparently Autel Maxicheck Pro does the ABS activation also.
     
  18. Jimbob

    Jimbob SITE SUPPORTER- SILVER GOLD MEMBER

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    Yes, you would have to do it in a location without too many curves or grades. Lol
     

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