<VV> Brake Fluid Tech tip

[Chris & Bill Strickland]

Wonder if this works to test gas tanks for fuel condition and corrosion 
--- ???  Or coolant systems in water pumpers They all sound like 
batteries of various sorts.

Remove the brake fluid reservoir cap, and set the DVOM to read voltage 
on the lowest voltage range of the meter. Place one of the DVOM probes 
into the brake fluid, and the other against the body of the master 
cylinder. The voltage should be no greater than 0.3 volts. If the 
voltage is higher, this indicates a galvanic reaction, and means that 
there is an unacceptable level of moisture in the brake fluid.

The majority of today's braking systems use a combination of dissimilar 
metals. Manufacturers use aluminum in pistons and housings, steel in 
some wheel cylinders and brake lines. [and copper inside lines]

When moisture mixes with brake fluid a galvanic action can occur. 
Galvanic action is similar to the operation of a battery. The more 
moisture in brake fluid, the higher the galvanic reading and the greater 
the corrosion it causes.

from http://www.cdxetextbook.com/brakes/brake/brakes/repbrakefluid.html

Bill Strickland