Chevrolet Equinox Service Manual: Master Cylinder Bench Bleeding

Warning:Refer toBrake Fluid Irritant Warning.

Caution:Refer toBrake Fluid Effects on Paint and Electrical Components Caution.

Secure the mounting flange of the brake master cylinder in abench vise so that the rear of the primary piston isaccessible.Remove the master cylinder reservoir cap anddiaphragm.Install suitable fittings to the master cylinder ports thatmatch the type of flare seat required and also provide for hoseattachment.Install transparent hoses to the fittings installed to themaster cylinder ports, then route the hoses into the mastercylinder reservoir.Fill the master cylinder reservoir to at least the half-waypoint with GM approved brake fluid from a clean, sealed brake fluidcontainer. Refer toMaster Cylinder Reservoir Filling.Ensure that the ends of the transparent hoses running intothe master cylinder reservoir are fully submerged in the brakefluid.Using a smooth, round-ended tool, depress and release theprimary piston as far as it will travel, a depth of about25-mm (1-in), several times. Observe the flowof fluid coming from the ports.

As air is bled from the primary and secondary pistons, theeffort required to depress the primary piston will increase and theamount of travel will decrease.

Continue to depress and release the primary piston untilfluid flows freely from the ports with no evidence of airbubbles.Remove the transparent hoses from the master cylinderreservoir.Install the master cylinder reservoir cap anddiaphragm.Remove the fittings with the transparent hoses from themaster cylinder ports. Wrap the master cylinder with a clean shopcloth to prevent brake fluid spills.Remove the master cylinder from the vise.