2009 GMC Envoy Brake Master Cylinder

The recommended torque is 36 Nm (27 lb-ft).

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 also provide for hose attachment, and install transparent hoses to the fittings installed to the master cylinder ports, then route the hoses into the master cylinder reservoir, fill the master cylinder reservoir to at least the half-way point with GM approved brake fluid from a clean, sealed brake fluid container, release the primary piston as far as it will travel, a depth of about 25 mm (1 in), several times, continue to depress and release the primary piston until fluid flows freely from the ports with no evidence of air bubbles, remove the transparent hoses from the master cylinder reservoir, install the master cylinder reservoir cap and diaphragm, remove the fittings with the transparent hoses from the master cylinder ports, and remove the master cylinder from the vise.

Remove the brake fluid from the master cylinder reservoir and discard it in an approved container, spread the master cylinder reservoir locking tabs, and lift the reservoir upward from the master cylinder, clean the area surrounding the master cylinder and the master cylinder body with denatured alcohol and a clean shop cloth, and remove the master cylinder reservoir seals.

The brake fluid may be topped off up to the maximum-fill level.