GM 19417194
Master Cylinder

Press and release the Brake Pedal a few times to lessen the power vacuum Brake Booster transferable vacuum during cylinder replacement. Insert a proper tool into the master cylinder reservoir to drain and dispose of its brake fluid correctly. You should clean the master cylinder parts using denatured alcohol to get rid of dirt buildup then let everything dry. Unplug the brake fluid level sensor wire connection and disconnect the master cylinder's secondary brake pipe fitting by sealing it with caps. After detaching from the master cylinder primary pipe you need to secure the brake pipe fitting with a cap and to block the master cylinder outlet port. Take the master cylinder nuts off and withdraw the master cylinder with its o-ring seal from the Brake Booster unit checking if the o-ring has issues and replacing it when required. For new master cylinders always run a bench bleed before final installation. Fold the o-ring seal into the groove of the master cylinder body before inserting it with the master cylinder onto the power vacuum Brake Booster. Fasten the master cylinder nuts at 30 nm torque (22 lb ft). Join the master cylinder primary brake hose from the outside and torque it to 17 nm (13 lb ft). Then connect the master cylinder secondary brake hose from the inside and torque it to the same torque value. Reinstall the brake fluid sensor wires before adding brake liquid into the master cylinder reservoir and conducting hydraulic brake bleeding procedures.

Disconnect the brake fluid level indicator switch electrical connector and the master cylinder secondary brake pipe fitting.