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Brake bleeding problem

Discussion in '80-Series Tech' started by Brian894X4, Mar 3, 2007.

  1. Brian894X4

    Brian894X4

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    Brake bleeding problem-update

    Rig is a ’95 FZJ80 with about 86K miles on it. I bought it last month. Rear appear to be original calipers and about 50% pads. Pads were replaced by the PO a while ago. Front is newer rotors, but recently turned and recent brand new calipers and pads done by Midas by the PO.

    Brakes have been very mushy since I’ve had it. My thoughts were a very poor brake job by Midas. Specificly bleeding. When I got it, the brake resevor was overfilled. I decided to bleed myself using a vacuum pump.

    Started at the RR and then noticed that the calipers became loose after bleeding, but tightened up after pumping the brakes, so the procedure I did was, vacuum bleed, tighten bleeder, pump brakes, vacuum bleed, etc. Then did the LR, then the LSPV. The pedal seem to get really firm. Much more than ever before. I thought I fixed all my problems. At that point I had used a whole large bottle of DOT 3.

    Then I started on the RF. I got nothing but air after multiple vacuum pumps. Finally got a tiny bit of fluid and eventually a little more, but not much at all. I was thinking that maybe the bleeder was sucking air from behind since it looks like a POS aftermarket caliper. Tried the LF with same results. Lots of air, then a tiny bit of fluid after a while.

    But pedal seemed firm, so I started the engine and the pedal went straight to the floor. Pumped a few times and it helped a bit then back to the floor.

    So, my question is this. Could I really have had that much air the front brakes, yet they still somewhat functioned? And if air is my problem, why are the brakes even worse, now that I’ve moved a good chunk of that air out, although apparently not all of it.

    I’ll guess I’ll just keep bleeding and seeing what happens. But I’ve spent a good couple of hours vacuum bleeding the front and I’m still only getting very little fluid out, compared to the rear which bleed very nicely. Any thoughts would be appreciated. Sorry for the long post.
     
    Last edited: Mar 4, 2007
  2. little_joe

    little_joe SILVER Star

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    Hey Brian, maybe try a conventional bleed on the front brakes - just crack one bleeder and pump the pedal until you get fluid coming out. I had to do this a few times on my old mini when the hand-pump vacuum bleed didn't work well.

    And by vacuum, do you mean vacuum on the bleeder or at the MC? (ie the Motive Power Bleeder or whatever it's called)
     
  3. Brian894X4

    Brian894X4

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    Yep, vacuum on the bleeder. I will try the pedal pump method if I can find some help. Wife is out of town and I'm on my own right now.
     
  4. Brian894X4

    Brian894X4

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    This brake bleeding thing has just turned out to be a horrible experience. I can't believe the LC is this hard to bleed. I've got 2 days into it now and at least 3 full size bottles of fluid through it. A friend help me by pumping the brakes. I bleed exactly per the FSM numerous times, including the Master cylinder.

    The problem is the pedal is still pretty mushy, but doesn't go the floor with the engine off. With the engine on, it goes to the floor like a dead master cylinder.
    But before I started bleeding, my only issue was a slightly mushy pedal, so I'm confused at how the problem got to the point that it's now undrivable, by me bleeding it. I'm wondering if new fluid somehow pushed a master cylinder that was already on the edge of going out, over the edge. Or if I somehow got more air in the system than it had before. I'm just at a loss.

    One major point of confusion is the FSM says to "bleed the by-pass pipe". But there's no mention of where this is. I assume they mean bleed the LSPV, which I've done numerous times. Is there another "by-pass pipe" that I'm missing.

    My next step is to just continue to bleed for a few more hours and a few more quarts of brake fluid and if that doesn't work, then a new master cylinder or rebuilt kit, if I can find one. It's a '95 FZJ80 with 86K miles. I guess it's conceivable that the MS is toast.

    I've been reading up on everything I can find in the search engine here, and seems that I'm not alone. This appears to be a right of passage in owning an LC.
     
    Last edited: Mar 4, 2007
  5. bricat

    bricat SILVER Star

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    How about getting a mobile mechanic to pop in and fix it. Also would be able to diagnose any other problem you might have missed cheers Brian
     
  6. cam75w/ls1

    cam75w/ls1

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    It could be the bypass pipe on the ABS. I'm not familiar w/ the LC ABS since mine doesn't have it but I"m a mechanic for a living and on some vehicles w/ ABS the dump valve opens and bypasses into the bypass pipe to relieve pressure to the brakes. What I would try to do since your alone, is use vacuum hose to bleed your brakes. Need to get some 5/16 hose thats long enough to go from the bleeder to a 1/4 full bottle of brake fluid. I open the front bleeders w/ the hoses submerged in the brake fluid in the bottles and pump till the reservoir is low and refill. I work alone so I have to bleed brakes by myself.
     
  7. cam75w/ls1

    cam75w/ls1

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    Forgot to mention the bypass pipe. Some of the Fords and GMs have the bypass on the ABS pump and have a bleeder on the ABS pump itself. It could be there on yours. Don't know for sure though....:confused:
     
  8. Brian894X4

    Brian894X4

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    Quick question:

    Is it OK to bleed the brakes with the engine running? I just figured this would be easier on my wife pushing the pedal with the assistence of the vacuum booster. Bad idea?
     
  9. photogod

    photogod

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    I always bleed with the engine off.
     
  10. Brian894X4

    Brian894X4

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    Now that I've done it with the engine running, it is easier on the person pumping the pedal and does make it go a little bit faster from that aspect, but no change otherwise.

    I've finally got nice good flow and air-less fluid out of all four corners, but the LSVP is still giving me headaches. I ran out of brake fluid...used 7-8 full size cans so far..so I'll be back at it tomorrow. Still have the pedal going to the floor with the engine on, but I did the pedal pressure and hold test and the MS does not slowly lose pressure and go to the floor, so I think my only problem is air in the system.

    I'm wonder if the problem with these LC80s is the return pipe from the LSVP to the ABS accuator. If wonder air gets trapped in that pipe and that's why it takes so long to bleed. I also wonder if air in that pipe is the source of the soft pedal and less effective braking everyone complains about.

    I've read time and again about almost every single part being replaced, yet braking never seems to return to what it was from the factory. These LC80s used to stop from 60-0 mph in 150 feet, so the braking system is not ineffective...as the 100 also brakes from the factory 60-0 in the same distance.

    So, I wonder if there's just a lot rigs out there with air still in the brake system because it hasn't been fully and properly purged?
     
  11. trd55

    trd55

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    Welcome to the club. This can be very disheartening on somebody who think of himself as a 3 bannana(sp?) guy.

    I too am having the same ploblem you are having. I went to having decent brakes, and pulling to one side to pedal hitting the floor. I am only on 1-1/2 bottles of fluid, after a rebuilt front caliper and inspected nearly new rear wheel cylinder. The way I figure, I was getting air from the bleeder valve through the threads. Any info on using thread sealant on the bleeder valve? I tried using teflon, but after one round of open close, it is screwed. I gave up on the vacumm and am going to attempt the hose in a bottle thing which is basically the same as the vacumme bleeder, but I am only going to crack the bleeder screw enough to release a controled amount of fluid, since I have nobody to help me. Is it better to do both fronts and backs at the same time?

    -D
     
  12. Darwood

    Darwood

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  13. Rookie2

    Rookie2

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    Hmm... I don't recall hearing folks complain about the brakes being hard to bleed on these. I had never done it before. Bought a bottle of Valvoline Synthetic, had the wife run the pedal, crack bleeder, push pedal to the floor, close bleeder, release pedal and pump till stiff, repeat until fluid is clean. There is a specific order between the four corners and the LSVP. Anyways, took just shy of one 16 oz bottle to have clean fluid throughout. If that's not working, you may have a problem somewhere else.

    :beer:
    Rookie2
     
  14. stevek

    stevek

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    Thats what I use on the 80 too. I think these things have to be power bled without a doubt!
     
  15. Brian894X4

    Brian894X4

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    I would imagine that if the bleeder valve was screwed to the point it could suck in air, it would pump out brake fluid when you pressed the pedal, especially with the extremely high pressure it puts out.
     
  16. trd55

    trd55

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    Not sure what to think. There is always the fact that liquid is thicker that air, and it is not getting thru the threads when pushing out (surface tension), but air get sucked in under vacumm.

    Got home today with thread sealant (white pipe dope type stuff). Pulled bleeder screw off, applied sealant, and bled with my first empty can and hose. Need to make sure to open valve enough to puch enough fluid to get air out of hose. All went great. Went through a normal bleeding proceedure. Pedal is back up. Bled front caliper that seems to be low on pressure. Problem seems to have reduced, but still have a slight pull to the left. Not as bad as before. Pretty confident in last bleed. Could the hose be collapsing and not allowing equal pressure to both sides? Possible internal hose failure blocking line? Rear drums are adjusted equally through the backing plate, so that takes that idea out.

    Any other ideas???

    Darius
     
  17. lovetoski

    lovetoski SILVER Star

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    Wow - you've gone through a lot of brake fluid. The wife's gotta have some strong quads...

    I've had some trouble getting all the air out on my 80. Seemed that the LPSV was the trouble spot. Did a lot more bleeding there, seemed to make the difference.

    Ended up using a sequence like this:
    RR
    LR
    LPSV
    RF
    LF
    LPSV
    RR
    LR
    LPSV
    RF
    LF
    LPSV
     
  18. rockclmbr

    rockclmbr

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    I've gone through the same headache you are experiencing. In the end I dropped the 80 off at my trustworthy mechanic and they used vacuum attached to the bleed valves. The brakes are the best they have been in a long time (still not as nice as the 100).
     
  19. Brian894X4

    Brian894X4

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    Thanks for the info. Sorry, I just PM'd you after I read your thread from last year and didn't realize that you responded to my post.

    I've just got done pedal bleeding it over the last 5 days and after using about 4 gallons of fluid (it's one clean system now) I still have some air coming out of the LSPV.

    Test drive resulted in the same problem even after all that bleeding, so I'm pretty confident now, after reading your posts and old thread that I need to have it professionally bled and that should solve my problem.