Brakes driving me nuts.....

Airmapper Aug 27, 2019

  1. Airmapper

    Airmapper First Fill-Up (of many)

    Messages:
    323
    Location:
    Bowling Green, KY
    Part venting part plea for ideas or backup on my suspicions. It was all supposed to be a simple swap of new brake pads and flush the fluid getting ready for a trip. Now my X seems fubar'ed.

    When I got done, with the engine running, pedal is soft and goes to the floor. It will build pressure with the engine off.

    Only thing I did different this time than any was I was bleeding in the usual pattern but doing my pads as I went. So take off a wheel, swap pads, compress the cylinder, slurp up the fluid in the reservoir (because of course I puked old fluid back in) and minding not to get every last drop. New fluid in, then bled the line I just did using a compressor run vacuum bleeder, not exactly high pressure but would suck old fluid through.

    ABS unplugged, I'm pretty sure I never let the reservoir go completely dry, because I was very aware and cautious of doing just that.

    The biggest hitch I ran into was the rear drivers caliper bleeder snapped off. One of the guide pins was also seized so I patched it up with an old pad to hold me over, and figured I would get back to it later. Now I suspect I have air in the lines it's the only line I can't bleed, so either that is where my problem is or I'm just royally screwed some other way.

    I did notice some tighter drag than normal on the front drivers side once the new pads were on. With effort you could still make the wheel move by hand, so it wasn't locked, and I assumed everything just needed to seat in. The passenger front spun freely after the new shoes. Thinking back it might be another seized guide pin I didn't notice, maybe.

    Normally a hang up like this wouldn't be a big deal, assuming I have time to handle it. But, I'm going on a 5 day trip this weekend that if I don't have this fixed by the end of tomorrow I may not be able to swing, and I've been looking forward to it for months.

    I have a new rear caliper with bracket on the way, should get here sometime tomorrow. I took tomorrow off work to try to deal with it, but until then I can't do much other than be pissed and it's all on the wire for tomorrow, my part probably won't arrive early, and who knows what else I'll fubar swapping it out. I have to leave the next morning....that is if I can even go. Looking into taking another vehicle, I got my beater 4runner, but it's not set up for camping at all.
     
  2. Prime

    Prime Some Kind of In Charge? Admin

    Messages:
    37,267
    Location:
    Denver-ish
    The 2nd gen brakes are so poorly designed, it's not even funny. That little rubber sleeve inside every lower caliper pin? Yeah. I threw those out after I found that ALL of my lower caliper pins were seized.

    As far as your pressure goes, I hate to say this, but the best way to bleed these brakes is to take it to the dealer and have them use the Consult tool. It uses the ABS motor to bleed them. I've heard too many time about people cracking the lines open and not being able to get the pressure back until having it power bled.
     
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  3. pharaon19

    pharaon19 Test Drive

    Messages:
    10
    Try bleeding the brakes with the ABS plugged in and the car running, from what I've been reading that should allow you to open the ABS valves and completely bleed them. Otherwise dealer with the tool
     
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  4. Airmapper

    Airmapper First Fill-Up (of many)

    Messages:
    323
    Location:
    Bowling Green, KY
    Good tips thanks.

    I ordered this which may do some of the "dealer only" stuff. On the X I'm not sure the auto bleed function works, but I think it will allow manually cycling the ABS motors individually. If it does not I may return it.



    I think I am going to try a "normal" bleed first thing once I get the new caliper on and see if that does the trick first.
     
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  5. Prime

    Prime Some Kind of In Charge? Admin

    Messages:
    37,267
    Location:
    Denver-ish
    Let us know on that! Super interested in being able to do it myself.
     
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  6. Airmapper

    Airmapper First Fill-Up (of many)

    Messages:
    323
    Location:
    Bowling Green, KY
    Well bad news, I didn't get it fixed. I was able to go on my trip with a borrowed vehicle, which was my Dad's newer Frontier. (I now want a Frontier pretty bad, having a truck bed was pretty sweet.)

    Good news is the gadget does cycle the individual ABS motors, which is cool. You can trigger them and it sounds a lot like when the traction control is working, a jittery grinding noise. It probably wasn't needed for this job but I'm going to keep it because it's one of those things that will probably come in really handy one day.

    Got the new caliper on the rear. Resumed bleeding. bled normally, no real change, might have improved a bit, maybe? Then cycled the motors, bled again, no change. I'm not really getting any confirmed air out of any of the lines. Using the vacuum bleeder sometimes it will suck air around the bleeder valve or nipple giving me a false bubble. Manual bleeding, I have not seen any bubbles.

    At this point I'm not sure it's air in the lines. If I hit the brakes really fast I can get them to hold, even got them to lock up a bit in the driveway. But as you hold the pedal the pressure just fades until the pedal hits the floor. I may not understand the brake system completely but my assumption with air in the lines I would expect the brake grip to be weak but still be able to pump up the pedal and hold it at some point. Not hit it hard, get some pressure, then have it slowly fade off.

    I can pump up the pedal with the engine off, no power assist. This has me confused, but perhaps it takes more pressure than I can apply to cause the seal bypass in the MC? Or at my leg pressure it's too slow to observe immediately.

    My theory is I fell victim to the ruining the MC seal by not blocking the pedal from going all the way down, and old fluid corrosion in the cylinder. I was bleeding by vacuum tool so wasn't worried about it, but I did use the pedal to try to pump up the compressed calipers and while I took little "bites" it's possible I took one too big and pushed it past it's usual travel.
     
  7. Just a Hunter

    Just a Hunter Bought an X

    Messages:
    59
    Location:
    Georgia
    Xterras can be picky in regards to the brake bleed sequence.

    Follow this order

    Brake bleeding:
    Pass (right) Rear / Driver (left) Front / Driver (left) Rear / Pass (right) Front
     
  8. Airmapper

    Airmapper First Fill-Up (of many)

    Messages:
    323
    Location:
    Bowling Green, KY
    I appreciate that info but I got it memorized already. At this point doing it the way I'm supposed to equates with doing the same thing over and over expecting different results.

    My main problem is are my symptoms consistent with air in the lines or am I wasting time repeating that process when I should be finding the real problem? If it's air I can keep bleeding.

    I don't have "soft" brakes. Soft implies they hold but are weak. My brakes feel like they grab then fade to nothing as the pedal drops.
     
  9. IM1RU

    IM1RU First Fill-Up (of many) Supporting Member

    Messages:
    342
    Location:
    SLC, UT
    Is that a driving situation feeling? .... Seems like you have a different problem. My brakes were vastly improved by doing a manual bleed with the engine running in the correct order.... might be dealer Consult visit time.
     
  10. JeffNJM3

    JeffNJM3 Test Drive

    Messages:
    40
    Try bleeding the lines out of the master, then into the abs pump, them out of the and pump. I Think where the lines out off the abs pump curve, air gets stuck in there. It's worth a shot!
     
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  11. Airmapper

    Airmapper First Fill-Up (of many)

    Messages:
    323
    Location:
    Bowling Green, KY
    Thanks for the assistance and participation in the discussion everyone.

    If anyone remembers Paul Harvey, here is the rest of the story (and I hope it is the end of the story.....)

    I think the soft pedal is a combination of some air in the lines and me expecting too much out of them. The X pedal has never been excessively firm and anymore I drive my 3rd gen 4runner 75% of the time which has always had a nice firm feeling pedal. I replaced the rear caliper and I think that let a crap ton of air in, I did 2-3 cycles more of bleeding, and that wheel bubbled out some air.

    But that's not all, front caliper had seized guide rods as well, I got distracted with the pedal issue, and they happened to be seized at a place where the new pads went on fine but dragged the rotor a bit. Drove it to work one day to feel it out, and ended up roasting that corner. On top that I may or may not have tightened the lugs right and came close to loosing that wheel on the road. Luckily I noticed it in time and got it tightened back up and limped home.

    Today I replaced the front caliper, rotor, and pads. I think I'm all good now. Driving it tomorrow to go biking. Probably need to replace the other calipers as well, but if they don't do anything weird I'm taking a break.

    Now I just need to get the hefty fab sliders on I got back in March, currently got the stockers off so my radiator is exposed. Had to miss out on about 2 invitations to go wheeling lately, getting to me.
     
  12. westslope

    westslope Bought an X

    Messages:
    90
    Location:
    Wildfire country, BC
    Well this thread is timely. Two days ago with the assistance of my wife, I flushed and bled the brakes. Brake fluid is clean, I did not see any air bubbles but the brakes were still soft and the VDC and Slip lights came on. The ABS brakes work just fine judging from one trial on a gravel pullout close to our neighbourhood. EDIT: I should add that the SES light never came on and the ECU did not throw any codes.

    So then I went back and did some more searching and reading. I found an earlier How-to post thread by Airmapper on the other site. If Airmapper who clearly had some experience and knowledge was having so much difficulty, what was a newbie like me to think?

    The Popular Mechanics page How to bleed your brakes the right way provides a good recipe and hints at what Prime wrote above:

    "As far as your pressure goes, I hate to say this, but the best way to bleed these brakes is to take it to the dealer and have them use the Consult tool. It uses the ABS motor to bleed them. I've heard too many time about people cracking the lines open and not being able to get the pressure back until having it power bled."

    The FSM recommends disconnecting the ABS and not running the engine. Above in this thread, pharaon19 recommends bleeding the brakes with the ABS working and the engine running. Apparently some modern auto manufacturers recommend a similar procedure.

    I thought about putting the X up on 4 jack stands outside and repeating the bleeding with the engine running but am wondering if I should just take the X to a Nissan dealer or qualified brake shop and save myself more time and frustration, at least until I have a better understanding of what is going on here.

    I have more brake work to do -- need to replace the rear axle seals, rear brake pads and possibly sliders -- and expect to renew the front brake pads in the next year or two, so I was hoping I could do this myself.
     
    Last edited: Nov 4, 2019
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  13. westslope

    westslope Bought an X

    Messages:
    90
    Location:
    Wildfire country, BC
    Follow up.

    Dished out C$95.77 (US$72.79) for a brake bleed at Kal Tire this morning. Brakes are firmer. The VDC and Slip lights are gone. The ABS light came on as I rolled out the garage in the morning and it was gone as soon as the brakes were bled.

    Kal Tire topped up the reservoir with my Napa Auto Parts Dot 3 brake fluid.

    I'm happy. May attempt to bleed the brakes myself in the future if I procure a gadget like the one Airmapper posted above.
     
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