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#1
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Testing Brake Fluid
I read that I can determine the moisture content of the brake fluid in my
car by using a DMM (digital multimeter). Negative lead to the -battery term and the positive lead to the brake fluid in the reservoir. Anything below .3 volts is acceptable. Any comments on the validity of this method? |
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#2
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Testing Brake Fluid
On Jun 22, 3:07*pm, "ED" > wrote:
> I read that I can determine the moisture content of the brake fluid in my > car > by using a DMM (digital multimeter). Negative lead to the -battery term > and the positive lead to the brake fluid in the reservoir. Anything > below .3 volts is acceptable. > Any comments on the validity of this method? That would vary wildly depending on the multimeter. Completely unreliable. Google brake-chek for a german optical tester. |
#3
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Testing Brake Fluid
"ED" > wrote in :
> I read that I can determine the moisture content of the brake fluid in > my car > by using a DMM (digital multimeter). Negative lead to the -battery > term and the positive lead to the brake fluid in the reservoir. > Anything below .3 volts is acceptable. > Any comments on the validity of this method? > > Trying to avoid getting the fluid changed? -- Tegger |
#4
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Testing Brake Fluid
On 06/22/2011 12:07 PM, ED wrote:
> I read that I can determine the moisture content of the brake fluid in my > car > by using a DMM (digital multimeter). Negative lead to the -battery term > and the positive lead to the brake fluid in the reservoir. Anything > below .3 volts is acceptable. > Any comments on the validity of this method? > > in theory it could work, but it depends on the electrode metal and the type of metal the cylinder is made of. cast iron has a different electrode potential to aluminum, which has a different potential to stainless, which has a different potential to chrome plated brass, which has a different potential to only partially chrome plated brass, etc. so, unless you know the potentials for your probes and your system respectively, or you use a specific known probe calibrated for the system you're testing, you're completely in the dark. -- nomina rutrum rutrum |
#5
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Testing Brake Fluid
In article >, ED > wrote:
>I read that I can determine the moisture content of the brake fluid in my >car >by using a DMM (digital multimeter). Negative lead to the -battery term >and the positive lead to the brake fluid in the reservoir. Anything >below .3 volts is acceptable. >Any comments on the validity of this method? Problem is that this is very dependant on the electrodes being used. If you had a couple standard electrodes, though, you could do it accurately. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#6
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Testing Brake Fluid
"Scott Dorsey" > wrote in message news:itvfi1> > Problem is that this is very dependant on the electrodes being used. > If you had a couple standard electrodes, though, you could do it > accurately. > --scott > -- I dont think even that would help this method, Scott. The most accurate method I know of for water in polyols is Karl Fischer titration....and that is beyond the cost limitations and technology of most people who want a value for water in polyols. There are some test strips: http://www.gwrauto.com/stripdip.htm that may be economical for shop use. Discussion: http://brakefluidtest.com/news/speci...vs-water.shtml |
#7
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Testing Brake Fluid
On 06/23/2011 07:17 AM, hls wrote:
> > "Scott Dorsey" > wrote in message news:itvfi1> >> Problem is that this is very dependant on the electrodes being used. >> If you had a couple standard electrodes, though, you could do it >> accurately. >> --scott >> -- > I dont think even that would help this method, Scott. > > The most accurate method I know of for water in polyols is Karl Fischer > titration....and that is beyond the cost limitations and technology of most > people who want a value for water in polyols. > > There are some test strips: > http://www.gwrauto.com/stripdip.htm > > that may be economical for shop use. > > Discussion: > http://brakefluidtest.com/news/speci...vs-water.shtml there aren't many modern vehicles with brass brake componentry - "copper" is just something to get the ignorati worried about so they pay for more diagnostics and the service industry concerned that they "don't get left behind" and buy new equipment. as for test strips, they're ancient history. <http://www.otctools.com/products/brake_fluid_safety_meter> <http://www.bestbuyautoequipment.com/Storm-by-Central-STO3S121-p/sto3s121-01.htm> -- nomina rutrum rutrum |
#8
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Testing Brake Fluid
hls > wrote:
>"Scott Dorsey" > wrote in message news:itvfi1> >> Problem is that this is very dependant on the electrodes being used. >> If you had a couple standard electrodes, though, you could do it >> accurately. > >I dont think even that would help this method, Scott. It's true that there's other stuff that will increase conductivity, but I think everything that will possibly increase conductivity is going to be something you probably don't want in your brake lines. But, unless you have calibrated electrodes and a calibrated volume, you can't get resistivity from resistance. >The most accurate method I know of for water in polyols is Karl Fischer >titration....and that is beyond the cost limitations and technology of most >people who want a value for water in polyols. That seems severe overkill for the application, and definitely not an easy kitchen job. >There are some test strips: >http://www.gwrauto.com/stripdip.htm > >that may be economical for shop use. Frankly, it seems easier to change it than to test it, although I realize some newer vehicles with ABS systems can make it more difficult to change. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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Testing Brake Fluid
On 06/23/2011 08:00 AM, Scott Dorsey wrote:
> > wrote: >> "Scott > wrote in message news:itvfi1> >>> Problem is that this is very dependant on the electrodes being used. >>> If you had a couple standard electrodes, though, you could do it >>> accurately. >> >> I dont think even that would help this method, Scott. > > It's true that there's other stuff that will increase conductivity, but I > think everything that will possibly increase conductivity is going to be > something you probably don't want in your brake lines. > > But, unless you have calibrated electrodes and a calibrated volume, > you can't get resistivity from resistance. > >> The most accurate method I know of for water in polyols is Karl Fischer >> titration....and that is beyond the cost limitations and technology of most >> people who want a value for water in polyols. > > That seems severe overkill for the application, and definitely not an > easy kitchen job. > >> There are some test strips: >> http://www.gwrauto.com/stripdip.htm >> >> that may be economical for shop use. > > Frankly, it seems easier to change it than to test it ain't that the truth. while i'll take testing over superstition every time, brake fluid, with its attendant seal swelling/degradation problems, and known absorption profile, is simply not worth it - just change every other year. testing may be useful for shops where they have a new customer and an unknown service profile, but for an owner that knows their vehicle's history, it's pointless. > , although I realize > some newer vehicles with ABS systems can make it more difficult to change. that may have been the case when they first came out, but these days, it's really not a problem. > --scott > -- nomina rutrum rutrum |
#10
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Testing Brake Fluid
"Scott Dorsey" > wrote in message ... > hls > wrote: >>"Scott Dorsey" > wrote in message news:itvfi1> >>> Problem is that this is very dependant on the electrodes being used. >>> If you had a couple standard electrodes, though, you could do it >>> accurately. >> >>I dont think even that would help this method, Scott. > > It's true that there's other stuff that will increase conductivity, but I > think everything that will possibly increase conductivity is going to be > something you probably don't want in your brake lines. > > But, unless you have calibrated electrodes and a calibrated volume, > you can't get resistivity from resistance. This is true. Conductivity or resistivity measurements will respond to various types of contaminants in the brake fluid, to temperature, etc. But maybe you dont really need a very accurate measurement. I think it would be cheaper and better just to flush out the old stuff and replace every couple of years. I still have that #@& Reatta that has the very special braking system. If you dont flush that one every couple of years, you get to buy a new or rebuilt master cylinder, which - last I heard - cost the better part of a couple of grand. |
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