Brake fluid change interval car vs motorcycle

Discussion in 'The Garage' started by Project84, Oct 10, 2017.

  1. Jack90210

    Jack90210 quia ego nominor leo

    Joined:
    Oct 11, 2004
    Oddometer:
    16,408
    Location:
    :jack
    I thought about getting a refractometer tester, justifying by thinking a) it would be a lifetime tool, and b) it might save me some work when the brake fluid is older but hasn't absorbed much water. Unfortunately it would probably do the opposite, as it did in your example. :lol3
    #61
  2. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    Well I changed out the brake fluid in my Pontiac today. 60k and 20yrs old. It was dark for sure. Advanced Auto has a Valvoline deal going on now. Used almost 2 big bottles till it was clear. Need to hit some dirt and activate the fluid left in the ABS unit. I'll do it again in the spring after tons of winter ABS fluid action.

    Told my wife she's the best ever brake pumper and I love her. :-)
    #62
  3. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    What does that mean off the scale with a brake fluid tester?
    #63
  4. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    How and where does it breath air.
    I was looking at my car one today and saw a sealed plastic tube for the fluid and a cap with full rubber seal.and no sign of a vent hole. Just curious.
    #64
  5. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    Now I've read that all brake fluid is really synthetic DOT 3 and up?
    And synthetic in the bottle is just marketing?
    #65
  6. motu

    motu Loose Pre Unit

    Joined:
    Dec 28, 2001
    Oddometer:
    6,396
    Location:
    New Zealand
    Kind of like when you go over the red line on the tacho.
    #66
    MotoChris521 likes this.
  7. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    I get that from a scale perspective, but what does this tester read? What properties are bad on this fluid even though it looks good?
    #67
  8. motu

    motu Loose Pre Unit

    Joined:
    Dec 28, 2001
    Oddometer:
    6,396
    Location:
    New Zealand
    They test for water content. I sometimes use a multimeter in brake fluid or coolant too...that's going to confuse you even more.
    #68
  9. advNZer?

    advNZer? Long timer

    Joined:
    Dec 31, 2008
    Oddometer:
    3,568
    Location:
    Wellington,New Zealand
    if in doubt flush it out.What have you got to lose.?
    #69
  10. alexw

    alexw n00b

    Joined:
    Apr 8, 2010
    Oddometer:
    7
    Location:
    Perth, Australia
    The cap allows air in, there is usually a tiny hole.
    As said previously, some master cylinders use a rubber gasket to separate the fluid from the air side.
    #70
  11. calum

    calum Adventurer

    Joined:
    Jun 30, 2015
    Oddometer:
    90
    Location:
    UK
    Has anybody actually seen a brake failure due to old fluid?
    #71
  12. PunkinHead

    PunkinHead Moobless Adventurer Super Supporter

    Joined:
    Dec 10, 2005
    Oddometer:
    9,575
    Location:
    Land of Walmart Shoppers
    Yes. I've seen dead abs units with debris in them and plenty of frozen calipers.
    #72
  13. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    Interesting.
    I'm going to look at mine.

    After many years of washing engines and advice on how to do so properly I've never once heard anyone mention cover your brake fluid cap.

    I assume this hole system is a 2 part offset shielded design so it's not just a single hole that provides direct access for water, dirt and grime to enter.
    #73
  14. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    Is that resistance in the fluid? Is there a baseline and then a max range?
    #74
  15. shinyribs

    shinyribs Thumpers for life

    Joined:
    Sep 24, 2011
    Oddometer:
    4,228
    Location:
    The South
    A lot of bikes have direct vents to atmosphere. I know my old Ironhead did. I think a CBR master cylinder I used once did, too? If you were working on the bike ( Sportster) and spun the master cylinder out of the way it would leak out! When I saw it I laughed and called it a Harley thing, but then I've noticed it on quite a few bikes since. At one point I figured it might be a necessity for systems with small reservoirs ( to prevent pulling it itself in to a vacuum?) , but none of my dirt bikes have had this vent and they have tiny reservoirs.

    I don't know why some bikes have vents, but they definitely do, and I'm sure the fluid in those systems will deteriorate very quickly. A tightly sealed system, not so much.

    I don't have a time schedule on when I flush fluid, I just do it when I see the fluid looking the least bit mirky. If it's not clear, it comes out. Regardless of the number of wheels. ;)
    #75
  16. shinyribs

    shinyribs Thumpers for life

    Joined:
    Sep 24, 2011
    Oddometer:
    4,228
    Location:
    The South
    P.s.- If your bike's fluid suddenly needs flushing more often than usual, you've probably got caliper seals on the way out ( ingesting poo when retracting). When the bike gives you this clue it's time to freshen up the whole system before it pukes it's piston seals out on the next panic stop.
    #76
    Jack90210 and JCool like this.
  17. H96669

    H96669 A proud pragmatist.

    Joined:
    Nov 20, 2009
    Oddometer:
    5,624
    Location:
    Hiding off Hwy 6, B.C.
    Look it up online.That's Voltage you measure.Over 0.3V(?) and indicates galvanic corrosion is at play.

    Google?Multimeter testing/brake fluid/coolant.
    #77
    eakins likes this.
  18. trc.rhubarb

    trc.rhubarb ZoomSplat!

    Joined:
    Nov 15, 2011
    Oddometer:
    8,419
    Location:
    Concord, CA
    I've got a bike sitting in the garage right now that has gelled fluid and failed brakes. It will likely need new seals and multiple flushing.
    Story I got was that it has sat since 2007 or 8, mostly in a shed but also outdoors.
    I validated the engine/tranny as good yesterday, so now I can spend some time and money on the other parts.
    #78
  19. eakins

    eakins Butler Maps

    Joined:
    May 29, 2002
    Oddometer:
    32,460
    Location:
    Fort Collins, Colorado
    I will thanks.
    #79
  20. aldend123

    aldend123 Long timer

    Joined:
    Sep 1, 2011
    Oddometer:
    5,082
    Location:
    Bristol County MA
    MAC Tools sells a tester that reads up to 4% water content. I'm not certain, but I believe the primary factor behind that margin is driven by boiling point, not corrosion. I'd be hear otherwise though.
    #80