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Brake fluid - test or replace?Views : 1943 Replies : 27Users Viewing This Thread : |
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Nov 7th, 2021, 14:38 | #1 |
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Brake fluid - test or replace?
Hi,
Do you replace brake fluid routinely, or rely on a tester to tell you? It's been a couple of years, but my tester shows up green, so leave or replace? Thanks
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Nov 7th, 2021, 14:50 | #2 |
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Your tester will only test the fluid that's in the master cylinder, what about fluid in the calipers and lines?
My opinion...change it all
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Nov 7th, 2021, 19:23 | #3 | |
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Quote:
The business of changing brake fluid every 2 years or so is just made up by garages to invent business. I test it myself in all my cars (including my Porsche) and only change it if the tester indicates a need. Alan
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Nov 7th, 2021, 19:44 | #4 | |
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Quote:
Thanks
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Nov 7th, 2021, 20:01 | #5 |
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Replace it. As most excellently pointed put above, testers only work on the fluid in the reservoir.
Brake fluid is hygroscopic. Most contamination will come via the master cylinder cap, but sufficent molecular exchange takes place via the flexible lines themselves - hence fluid becoming visibly mucky with age - and the circulation of fluid around the system is so slow that it is not appropriate to rely on a tester that probably cost more than a bottle of decent fluid anyway. If one can't afford/can't be bothered to attend to something so critical they shouldn't be on the road. Do it exactly at the time/mileage interval Volvo recommend and throw the tester in the bin.
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Nov 7th, 2021, 21:32 | #6 |
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Opinions vary on this, just like almost every aspect of maintenance. The Porsche specialist I use, whom I trust, agrees with me that regular (annual) testing is perfectly adequate. I do the same on my other cars and bikes.
I have no view on what other people should spend their money on, but I certainly won’t encourage them to waste it unnecessarily. :-) Alan
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... another lovely day in paradise. Last edited by Othen; Nov 7th, 2021 at 21:38. Reason: Spelling |
Nov 7th, 2021, 23:14 | #7 |
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I neither routinely test or replace brake fluid, but then if I do anything to the brakes, even just replacing the pads, I'll get a bottle of fluid and bleed the system until the new fluid runs through, and then go round all four wheels again to be sure. At under a tenner a bottle it's cheap enough to do, big question is what to do with the row of half bottles in the garage that I'll never use because they may well be degraded by moisture?
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Nov 8th, 2021, 01:36 | #8 |
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I change it every 3 years.
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Nov 8th, 2021, 07:49 | #9 |
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I change every two years. I never understand why folks would skimp on brakes or tyres, it just doesn't make sense. Or indeed any other safety related item.
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Nov 8th, 2021, 07:54 | #10 | |
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Quote:
Let's think about it: the water vapour content of air by mass is about 0.01% in your cold garage, air weighs about 1.5kg/m^3, and there is perhaps 500cc of air in your half used bottle, so there is 0.005*1.5*0.0001kg = 0.00000075kg of water in the air inside the bottle or 0.75mg. The remaining brake fluid weighs about 500g, so even if it absorbed all the a water vapour (and it cannot of course because of the partial pressures) then that would only be 0.00075/500=0.0000015 or 0.00015% contamination. :-)
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