The Volvo Parts, Accessories &
Performance Specialists Since 1963

Dirty Brake Fluid?

2011-03-03 - IPD Staff

We’ve had some recent experience with brake fluid failure that was an eye opener.

Everyone has heard of the old tales of boiled brake fluid causing loss of brakes (something many now consider impossible) but what is really happening is that the water in the brake fluid is vaporizing and causing fade. Vaporized water is almost as bad as air bubbles in the system. Since brake fluid is hydroscopic (it gathers water from the air), it will fail without use or abuse. When your fluid turns brown, it’s from accumulation of water and rust in the system. Dark fluid can also be an indicator of rubber brake line degradation from the inside out. This is hard on the components and gives poor performance.

Recently, we saw rear brakes overheat and fade (melting brake pad material onto the rotor surface) under light usage. The fluid was dark brown so we flushed it and the problem went away. The theory is that the expansion of the water from heat caused the brake to drag and things continued in a downward spiral from there. The lesson is, if your fluid is not clear and golden, flush the system. You may be surprised at the results!