Many people think that brake fluid is like air in their tires; as long as it’s not low there, is little cause for alarm. In reality, nothing could be further from the truth. Many, many years ago when a discussion about brake fluid took place the buzz was about moisture content and the lowering of the boiling point when a certain percentage of moisture was present. About 15 years ago when standards were being developed for brake fluid change sequences it was validated that the real service issue with brake fluid was not the moisture content of the fluid but the dissolved mineral (copper) content of a vehicles brake fluid. A high level of dissolved minerals (copper) in a vehicles brake fluid can cause corrosion of brake and ABS component parts, allow the build-up of sludge and can be a leading indicator that the basic additive package such as rust inhibitors, anti-corrosion and lubrication additives are depleted.
The following photos depict a realistic testing of a vehicle’s brake fluid. Remember it’s not how long the fluid has been in the vehicle, how many miles are on the vehicle or how the brake fluid looks that determine if the fluid is still serviceable or not. It’s what the test results of the BrakeStrip Copper test shows that is important. This is a valid test to know if a brake fluid exchange is needed and an excellent way to extend the service life of brake systems internal components.
Is the brake fluid in this vehicle with over 150,000 on it good or bad? The fluid never has been completely or deliberately changed. Fluid has been added to top off the master cylinder infrequently. In the 150,000 it has had one front reline and warranty rear shoe replacement at 15,000.
Some shops during an oil change would look at the fluid level of the master cylinder, not even open the master cylinder cap and say everything look ok but is it really?
The fluid in this glass container looks very black and you may assume it no longer good. Don’t judge brake fluid by it appearance. This fluid will pass all specification tests. Remember there is no specification for appearance and in the past some OE manufactures did not add an additive that stopped premature discoloration of brake fluid.
Take a moment and wipe off the top of the master cylinder before removing the cap. It will help prevent any containments from entering the brake fluid.
After removing the cap, look at the fluid side before setting it down. Look for signs of contamination or a plugged vent hole if so equipped.
The BrakeStrip test strips come two different packages. The tube shown is the shop version and contains a bulk quantity (100) of test strips. The individual consumer pair pack is shown in Pic. 11
Remove one BrakeStrip test strip from the container and ……………
Come back next week because we will have more of the story on when you should change your brake fluid for Tech Tricks Tuesday.
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