Brakes Wheels 1st Gen Tires Boiling fluid out of the resevoir

Discussion in '1st Generation: 2002–06 R50, R53 & 2004–08 R52' started by mini_racer, Feb 19, 2011.

  1. mini_racer

    mini_racer Well-Known Member

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    #1 mini_racer, Feb 19, 2011
    Last edited: Feb 19, 2011
    Boiling? fluid out of the reservoir

    So, during some normal track fun time today. I obviously boiled some fluid right out the top of the reservoir cap. You can see it all over the outside of the reservoir, some on the booster, etc., etc. What is curious is that the brakes felt great, no fade, and no mushy pedal.
    I am running:
    -- The 1st Gen JCW calipers up front
    -- Pad are XP10s up front and XP8s in the back
    -- Fluid is Motul RBF 600
    -- ABS is always on, obviously
    -- I am also running highly efficient brake cooling ducts directed to the inside of the vented rotor, so they are cooling as much as possible.

    Can anyone help me make any sense of this?

    Also, I am not sure it this is a factor, but I did use the brakes enough for a some threshold braking, and I also invoked ABS ICE-MODE a few times, and I just pushed through the hard pedal.
    Could either of these two types of occurrences be a factor boiling, bubbling up, or backing up the fluid at the reservoir?
     
  2. mini_racer

    mini_racer Well-Known Member

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    Is it possible that instead of 'boiling' over, it was just expanding a little and pushing out the cap since I had it filled to the MAX line as I started the day???

    If so, I think I can fix this simple operator error.

    A nice and easy fix.......instead 'fill to the MIN line and check often' duh on me!

    Comments?
     
  3. RonsMinnie

    RonsMinnie New Member
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    #3 RonsMinnie, Feb 19, 2011
    Last edited: Feb 19, 2011
    My guess it is the latter (overfill) -- I would think you would have boiled over last summer when you were trying to melt down your calipers. Is all the same except for the added ducts?
     
  4. Mike

    Mike New Member

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    Regardless of what I've done to my brakes on the track, the only time I've had the fluid come out of the reservoir was when i filled it past the "max" mark, back in 2003 when i bought the car. I thought something was wrong with the car until I realized it was just user error. Overfilling slightly was a habit left over from racing old Alfas.
     
  5. TATTRAT

    TATTRAT Well-Known Member
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    gonna have to go in the overfill camp on this. The only times I have experienced the same situation, was when I thought I was doing the right thing and topping off all systems...when in fact, closed systems need room to grow, and if they are filled to the max, they only have one place to go, out.
     
  6. jasonsmf

    jasonsmf Active Member

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    I've also experienced brake fluid sloshing out of the cap during track use. Filling only slightly above the "min" mark and not all the way to "max" has completely solved the issue for me.

    Jason
     
  7. Nathan

    Nathan Founder

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    Been there, done that, have the stains from overfilling to prove it.
     
  8. mini_racer

    mini_racer Well-Known Member

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    Thanks guys, some issues are actually easily resolved. I think I might be able to prevent recurrence of this one. :eek:
     
  9. Metalman

    Metalman Well-Known Member
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    Add a brake reservoir sock to at least catch some of the leakage from dripping down and attacking your paint.

    [​IMG]
     
  10. Mike

    Mike New Member

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    That's funny to me because years ago on one of my Alfa racecars, I used... a cut-up sock. Never occurred to me to make it a real product!
     
  11. BThayer23

    BThayer23 Well-Known Member

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    Sounds like overfill. Sometimes when you swap from worn street pads to fresh track pads you can push the fluid back up into the reservoir. That'll push it over the max mark. The other option is a master cylinder leak, but you'd feel that in the pedal.
     
  12. Nitrominis

    Nitrominis Banned

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    I cut the toe ends of old socks and wear them when working on vehicles. Saves the forearms.

    As for the thread sounds like to much fluid. The BMW/MINI brake system fluid tank has a brake fluid level switch incorporated in it. So if you are low you will know it.
    I often see the fluid tanks over filled on MINIS especially after someone changes out the fluids and bleeds the system. Read the Bentley procedure and watch the levels. Remember that temperature and humidity can effect the total volume during the procedure? Less is better.

    A nice tool to have in the box for the track guys and very inexpensive.

    Draper 59078 Brake Fluid Tester Part No: BFT1

    [​IMG]
     
  13. ColinGreene

    ColinGreene Well-Known Member
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    Less is better should be taken with a grain of salt, always fill to the indicated level.
    I would rather have a mess than be in deep trouble or dead because of a brake failure.
     
  14. Nitrominis

    Nitrominis Banned

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    #14 Nitrominis, Feb 21, 2011
    Last edited: Feb 21, 2011
    DID I EVEN SAY FILL LESS THAN THE MINIMUM ??? GO READ MY POST AGAIN!


    And you should really apply at some auto shops to work on peoples cars with all you tremendous wisdom and experience....:crazy:

    Was I not clear on reading the Bentley manual and perhaps a call to the local BMW/MINI dealership service department for information on proper procedures? Haven forbid that I know what I am talking about after 30 plus years in the business...:lol:

    Grain of salt...? You should be the one that should never work on your own vehicles everyone's life and mine may depend on your lack of mechanical knowledge!

    Did I take you comment personal....yup! :Thumbsup:

    Brakes should never be taken for granted or worked on by the in inexperienced!!!

    Get one of these like I have and come post here!

    ASE A5 Brakes Certification Test Prep
    ASE Certifications

    Geeeez where do these people come from?
     
  15. ColinGreene

    ColinGreene Well-Known Member
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    Why would I want to apply to work at an autoshop, I work at Victoria's Secret.
     
  16. Nathan

    Nathan Founder

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    Yep, was just a full moon...

    The consensus said to fill a little over the MIN mark to be covered on track. Not sure what we are now arguing about.

    Personal attacks will not be tolerated at all.

    Do I need to bring this out of the closet?

    [​IMG]
     
  17. TATTRAT

    TATTRAT Well-Known Member
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    wow, are you are douche by profession? OR, are you overly sarcastic by profession? I don't have a gauge to distinguish.
     
  18. Nathan

    Nathan Founder

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    #18 Nathan, Feb 21, 2011
    Last edited: Mar 23, 2011
    This has to stop. (kinda funny when you realize the thread is about brakes)

    These personal attacks will not be tolerated at all. Disagree all you want, but there is no reason at all to call each names or insinuate any lack of skill by others.

    As I said, from posts others have made when topping off brake fluid in track day preparation it is a good idea NOT to fill to the MAX mark but to be above the MIN mark. In addition a sock of some type around the reservoir will help to sop up any leakage.

    On that note, this thread is was closed.
     
  19. mini_racer

    mini_racer Well-Known Member

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    So, with the reservoir filled to the mid-point my latest track adventures yielded an overflow free day. Huzzah!

    So, that's the ticket! Keep the fluid level well below the MAX line, for me the mid-point between MIN and MAX was plenty good enough. :Thumbsup:
     

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