How to Bleed a 2000 Blazer Master Cylinder

The 2001 Chevy Blazer came equipped with a Kelsey-Hayes 4WAL (four wheel anti-lock) brake system. Unlike other Chevy vehicles, this system is non-integral to the standard brake system and the master cylinder is separate from the ABS modulator valve assembly. When replacing the master cylinder in this truck, air trapped in the master cylinder must be removed before the master cylinder is replaced; no provision is made for removing air trapped in the master cylinder by cycling the modulator valve assembly, as is the case in systems like the Delphi 6.

Instructions

1

Secure the new master cylinder into a bench vise by clamping the mounting flange into the vise. Position the master cylinder so that the piston in the back of the cylinder bore is facing you. Attach the plastic fittings, supplied in the bench bleeding kit that comes with the master cylinder, to the threaded line openings in the side of the master cylinder. Push the clear plastic hoses, also supplied in the bleeding kit, onto the plastic fittings and secure them so they are inside the master cylinder reservoir, and below fluid level.

2

Fill the master cylinder reservoir with fresh brake fluid. Slowly depress the piston in the back of the master cylinder completely into the master cylinder, using a large screwdriver. Slowly release the piston while observing the fluid in the clear plastic hoses. Repeat this process until the fluid, circulating in the clear plastic hoses, contains no large air bubbles.

3

Top off the fluid level in the master cylinder and install the lid on the reservoir. Remove the clear plastic hoses and place the small rubber caps, supplied in the bleeding kit, on the bleeding fittings in place of the clear plastic hoses.

4

Carry the master cylinder to the truck and carefully and install it in the truck. Slide the master cylinder onto the two studs that attach it to the power brake booster, and secure it with the two 15-mm retaining nuts. Remove the plastic bleeder fittings, and screw the line fittings into the side of the master cylinder in their place. Tighten the lines securely with a line wrench.

5

Loosen the front brake line on the master cylinder. Have a helper push the brake pedal and hold it down, while you close the line. As you so, you will notice air escaping from the line as you loosen the fitting. Repeat this process until the fluid being pushed out of the line, when the pedal is pushed down, is free of air. Perform the same procedure on the rear brake line on the master cylinder. It may take several attempts to remove all of the air from the lines. Check the level of the fluid in the master cylinder and top it off with fresh fluid as the level drops below the "Min" mark on the reservoir.

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