GM 19209266
Master Cylinder

You need to set the Brake Master Cylinder's mounting flange in a bench vise for access to bench bleed it. Put on suitable fittings to the master cylinder ports and install them before linking transparent hoses to the required flare shape. Place suitable transparent hoses onto these master cylinder ports and guide them into the reservoir. Put delco supreme 11 brake fluid gm p/n 12377967 (or Canadian P/N 992667) and equivalent dot-3 fluid from a fresh container into the reservoir until it reaches halfway. Keep both hose ends dipped in fluid properly. Push and release the primary Piston slowly with a smooth tool until it returns 25 millimeters about 1 inch after observing fluid flow from the ports and feeling growing resistance before natural flow resumes. Complete the bleeding procedure when you see the fluid run undisturbed with no air. Pull the hoses out of the reservoir space then install the master cylinder parts followed by removing the fittings at each port location using a clean towel to protect from spills when you take away the master cylinder from the vise.

Begin repairs on the Brake Master Cylinder by placing its mounting flange in a bench vise to locate the primary Piston at the back. Install correct fittings on master cylinder ports that match necessary flared-seam standards and enable hose connections. Place these fittings on master cylinder ports and join them with transparent hoses into the reservoir. Place delco supreme 11 gm brake fluid reference numbers 12377967 and 992667 or equivalent dot-3 brake fluid in the reservoir until it reaches halfway while completely immersing hose ends in a clean sealed fluid container. Depress the primary Piston into a cylinder 25 mm using a smooth blunt instrument and watch fluid flow from both ports. You will notice air exits the primary and secondary pistons during the process as pushing force grows stronger and depression distance shortens. Push and release the primary Piston again to know fluid flows out of ports without trapped air. Replace the transparent hoses in the reservoir. Put back the master cylinder reservoir parts and take off the fittings with hoses from the provider ports. Soften spills during removal with shop cloth before taking the master cylinder out of the vise.

A replacement process for brake master cylinder starts by using the parking brake followed by wheel blocking. Place rubber caps or plugs on the exposed brake pipe fitting ends after you disconnect the brake pipes from the master cylinder to stop fluid loss and contamination. First install the rubber plugs before you detach the master cylinder nuts and bolts to extract the master cylinder from the vehicle. Remove all brake fluid from the master cylinder reservoir before you take away the reservoir container when needed. The master cylinder and reservoir connection should occur first after which you must fill the brake fluid reservoir before proceeding with bench bleeding of the master cylinder. Replace the master cylinder inside the vehicle by tightening its bolts and nuts to 36 N.m (27 lb ft). Attach the brake pipes to the master cylinder while tightening each pipe nut to 30 N.m (22 lb ft). Close off the hydraulic brake system through a thorough bleeding process.

Continue until fluid flows freely from the ports without air bubbles.

Observe the fluid flow from the ports; as air is bled, the effort to depress the primary piston will increase and its travel will decrease.

Disconnect the brake pipes from the master cylinder.

Remove it from the vehicle and secure the mounting flange in a bench vise, ensuring the rear of the primary piston is accessible.

A smooth, round-ended tool is used to depress and release the primary piston.

Clean the outside of the master cylinder reservoir around the cap.

Apply the parking brake and block the wheels.

Replace the master cylinder if any issues are found.

Inspect both for cuts, cracks, nicks, or deformation, and replace any affected components.

Reattach the master cylinder reservoir and its cap and diaphragm before finally installing the master cylinder back into the vehicle.

Connect the master cylinder fluid level sensor connector and bleed the hydraulic brake system.