How to Bleed a GM Master Cylinder
- 1). Mount the brake master cylinder in a vise and use vise caps to prevent damage to the master cylinder.
- 2). Detach the cap from the cylinder reservoir.
- 3). Install bleeding or clear silicone tubes of the proper length on the brake line fittings of the cylinder. Then bend the tubes over and into the reservoir. Most manufacturers deliver new or rebuilt master cylinders with bleeding tubes included in the package.
- 4). Fill the cylinder reservoir with new brake fluid DOT 3 up to a quarter inch of the reservoir's top. Check that the ends of the bleeding or silicone tubes are submerged into the brake fluid, or air will be reintroduced into the cylinder assembly.
- 5
Bench bleed the master cylinder prior to installation.
Depress the piston all the way into the bore slowly and then let go. Use a Phillips screwdriver. Keep depressing the piston until you see no more air bubbles going through the bleeding or silicone tubes. - 6). Remove the ends of the bleeding tubes from the cylinder reservoir.
- 7). Add more brake fluid to the master cylinder reservoir to bring the fluid to the previous level.
- 8). Install the brake master cylinder on your GM vehicle following the instructions in your vehicle's service manual.
- 9). Remove one bleeding or silicone tube at a time as you connect the brake lines to the cylinder line fittings.
- 10
Bleed the wheel cylinders and brake calipers following the bleeding sequence indicated by your car manufacturer. If necessary, consult your vehicle's service manual.
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