Replacing brake fluid requires more skills and tools than changing oil. Old school methods like the two man manual method or gravity bleeding, they still work. But they are not efficient ways at replacing large volumes of brake fluid in a short period of time.
No matter what method you use, remove as much of the old fluid from the reservoir as possible and pour in fresh fluid before you start any bleeding procedure. Machines that can power or pressure bleed a system can make a fluid flush as efficient and profitable as possible by removing all of the air from the system. These machines are changing because ABS and stability control systems. In the past, only 15 to 30 PSI was required to pressure bleed some systems. Some new systems with, let’s say, electronic brake distribution or automatic braking may require between 50 and 60 PSI to bleed the system and flush it. Always check the service information for the recommended pressure.
The other bleed or flush procedure that is often ignored is using a scan tool to actuate the hydraulic control unit. The worst fluid is trapped in the ABS valves and passages due to its non-integral design. Even if your scan tool does not have special test procedures to bleed the circuits of the HCU, you might be able to use a bidirectional control for the pump motor and valves to move the old brake fluid to the bleeders.
You should never be apprehensive about recommending brake fluid replacement if you have the right tools to test and flush the brake fluid. It is cheap insurance to protect the vehicle’s hydraulic components.
This video is sponsored by Advics.
