Power-Bleeding Brake Systems

Another problem with contaminated fluid is that of corrosion. Water in the brake fluid makes it corrosive to every part of the brake system. Regular flushing of brake fluid can prevent damage and expensive repairs.

On the DOT
When it comes to bleeding brakes and replacing brake fluid always use new brake fluid with the correct DOT rating. DOT is an acronym for the Department of Transportation.


Brake fluid is classified as DOT3, 4, 5 and so on. What the DOT ratings specify is the minimum boiling point of the brake fluid. Be wary of using some DOT 5 silicon-based brake fluids. These fluids get around the problem of water absorption by being not at all hygroscopic. While this solves one problem it creates another. Any water absorbed into the brake system settles down at the lowest point. It could not possibly settle in a worse place, as the lowest point is usually the calipers, which sit directly on top of the hottest part of the brakes.


While this may all seem confusing, the only strategy is to use only the DOT fluid rating recommended by the brake system manufacturer. Never use old brake fluid from a previously opened container. If the container has sat open, even with the cap on, it has probably already absorbed too much moisture to be used safely. Another important thing to remember about brake fluid is that is will destroy painted finishes. When working with brake fluid always keep plenty of cool, clean water nearby to immediately flush any spills. Always dispose of used brake fluid properly.

Brake by Numbers
Oddly enough most motorists don't consider flushing out the old brake fluid when replacing pads or calipers, or even when bleeding brakes. By using a power bleeder the entire system can be bled and flushed at the same time. The good news is these systems are now available at a price affordable to the do-it-yourselfer.