Contaminated brake fluid conducts electricity. In the automotive repair world, brake fluid is considered contaminated by two ways:
- Brake fluid is hygroscopic. Higher water content in brake fluid means lower boiling point. Brake pads/rotors get hot which can boil the water near near the pads/rotors. Boiled water is steam which is a compressible gas. Having a gas in the brake lines leads to a spongy brake pedal. So, high water content absorbed by brake fluid is considered contaminated.
- Brake lines contain copper. When microscopic bits copper get in the brake fluid, they can build up in the ABS unit causing failure of the ABS system. Thus, high amounts of copper mean contaminated brake fluid.
Since pure water and copper are both nonelectrolytes, how can brake fluid conduct electricity? Is there some other contaminant I am missing here that is an electrolyte? Is the water being absorbed, somehow, by the brake fluid not strictly H2O?
I am asking because I want to know if I can use a voltmeter to test if there is too much water contamination in brake fluid.