Automotive

Topping up brake fluid - Do you do this?

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  • Jul 23rd, 2015 3:14 pm
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Deal Expert
Mar 25, 2005
22706 posts
3696 upvotes
vik56in wrote: I checked out ,I may have been wrong that the brake fluid gets squirted out, the apt word is some brake fluid gets vapourised due to the heat generated due to the brake slamming. And Iam right about the bleeding of brake fluid when changing calipers and the necessity for dirty brake fluid to be changed to prevent damage to the braking system.
Vapourizing fluid does not mean it escapes the system and depletes the level. Plus no street car will be vapourizing fluid unless you are doing something stupid or have essentially water in the system.
Banned
Apr 5, 2013
5810 posts
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keenland
vik56in wrote: Thats enough ! You stop ! I admitted that I stayed corrected on the brake fluid squirting. I am correct on the other points. There are any number of forums on the internet to tell you about vaporization of brake fluids.
vapourization is VERY minimal at best and NOT very common or will cause catastrophic failure very quickly...don't try and justifiy BS...just don't answer if you don't know factually and i would respect more a question to gain knowledge, than links to try and justify BS...i am done now!
Sr. Member
Aug 5, 2012
699 posts
561 upvotes
MISSISSAUGA
cardguy wrote: vapourization is VERY minimal at best and NOT very common or will cause catastrophic failure very quickly...don't try and justifiy BS...just don't answer if you don't know factually and i would respect more a question to gain knowledge, than links to try and justify BS...i am done now!
You tried nitpicking on one squirting line ,which I even admitted that I was wrong and conveniently ignored the other correct lines in my original comment. You can't tell me to not answer when my other lines were correct .Then tried acting out yourself as the Mr I KNOW It All mechanic, but finally had to admit that vaporization does occur. Even I know that vaporization is very minimal and have never come across any catastrophic failure due to any brake fluid vaporization. Listen Now,brake fluid changes done every few years does give improved performances. There is no evidenced documented harm shown anywhere due to brake fluid changes other than some fewer bucks in the wallet.
"You have more chances of getting hit by a lightning or getting eaten by a shark than actually winning a lottery"
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User avatar
Nov 20, 2009
1323 posts
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39.0392° N, 125.7625…
Here is my definitive answer:
Glycol based braking systems are a closed system (sort of) A higher DOT number usually indicates a higher boiling point of the original, fresh fluid. Since it is not totally airtight, some H2O always gets into the braking system and the fluid is designed to absorb it. If it did not absorb it, it would collect in areas and start rusting the system. It would also freeze in cold weather preventing braking. This is why silicone based fluid is for racing only: it does not absorb water, has a really high boil point, and is flushed after every race.
As the various pistons operate, they shed some of their seal constituent material contaminating the fluid. The piston seals wipe the fluid back as they retract, but not completely 100%, so over time a tiny portion of fluid will escape. This could be over a period of years, and no leak will be apparent. The advantages of flushing the systems are to get rid of the contaminants and to loosen any bleed screws that might seize if they are never cracked open. I, ahem, don't follow this advice myself and have suffered as a result.
I would top up the reservoir as I could never be sure if the lowered level was due to brake wear or leakage/seepage.
Deal Addict
Feb 6, 2011
2372 posts
3008 upvotes
cardguy wrote: vapourized??? at what temperature does brake fluid become gas?
Depends on how much moisture is in the system. Moisture lowers the boiling point. Probably not an issue during city driving, but driving down long grades/mountains can cause issues.

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