The proper way is to secure the mounting flange of the brake master cylinder in a bench vise, remove the master cylinder reservoir cap and diaphragm, install suitable fittings to the master cylinder ports, and transparent hoses to the fittings installed to the master cylinder ports, fill the master cylinder reservoir to at least the half-way point with Delco Supreme 110 (GM P/N 12377967), ensure that the ends of the transparent hoses running into the master cylinder reservoir are fully submerged in the brake fluid, depress and release the primary piston as far as it will travel, continue to depress and release the primary piston, remove the transparent hoses from the master cylinder reservoir, install the master cylinder reservoir cap and diaphragm, and remove the fittings with the transparent hoses, and the master cylinder from the vise.
By BobGM Specialist
01/11/2022