What you'll need:
* Brake fluid: Use DOT 3 brake fluid, the type specified in your owner's manual (if you have it). Never use DOT 5, as it's silicone-based and incompatible with most brake systems.
* Clear tubing: About 3-4 feet long, with a small inside diameter to fit snugly over the bleeder valve.
* Wrench: The correct size to fit your bleeder valves (usually 8mm or 9mm, but verify).
* Container: To catch the old brake fluid.
* Helper: Having someone to pump the brake pedal makes the process much easier and faster.
* Gloves: Brake fluid is corrosive and can damage your skin.
* Shop rags or paper towels: For cleaning up spills.
* Owner's manual (if available): This will confirm the correct bleeding order and any Blazer-specific details.
Steps:
1. Locate Bleeder Valves: These are typically located on the top of each brake caliper (for disc brakes) and on the wheel cylinder (for drum brakes). Your Blazer likely has disc brakes in the front and drum brakes in the rear.
2. Bleeding Order: The correct bleeding order is crucial to ensure all air is removed efficiently. The standard order is:
* Rear passenger side (furthest from the master cylinder)
* Rear driver side
* Front passenger side
* Front driver side (closest to the master cylinder)
* Important Note: While this is the general order, *always consult your owner's manual if possible*. Some variations exist between models.
3. Prepare the System: Ensure the brake fluid reservoir is filled to the proper level. Keep an eye on the level throughout the bleeding process and add more fluid as needed to avoid introducing air.
4. Attach Tubing and Container: Place the container under the bleeder valve. Attach the clear tubing to the bleeder valve and submerge the other end in the container.
5. Bleeding Process:
* Have your helper slowly and steadily pump the brake pedal several times. They should not pump rapidly or hold the pedal down completely.
* While the pedal is depressed, slightly open the bleeder valve with your wrench to allow fluid and air to escape. You should see bubbles in the tubing.
* Close the bleeder valve as soon as the pedal goes to the floor.
* Repeat steps (a) through (c) until no more air bubbles are visible in the tubing. This may take several cycles per wheel.
* Repeat this process for each wheel, following the correct bleeding order.
6. Check Fluid Level: After bleeding all four wheels, check and top off the brake fluid reservoir.
7. Test Brakes: Once complete, test the brakes thoroughly in a safe, open area before driving. If the brake pedal feels spongy or the brakes are weak, you may need to re-bleed the system.
Important Considerations for a 1972 Blazer:
* Drum Brakes: Bleeding drum brakes can be slightly trickier. You might need to use a pressure bleeder for best results, especially if the system has been sitting for a while. A pressure bleeder maintains consistent pressure and helps force out trapped air more effectively.
* Age and Condition: The age of your Blazer's brake system means parts might be worn or damaged. Inspect brake lines, hoses, and calipers for leaks or damage before bleeding. If you find any issues, address them before proceeding.
* Master Cylinder: If your master cylinder is suspect (leaks, etc.), bleeding the brakes might only be a temporary fix. A failing master cylinder needs to be addressed.
Safety First: Brake fluid is corrosive, and working on your brakes requires caution. If you're unsure about any part of this process, take your Blazer to a qualified mechanic. Improperly bled brakes can be extremely dangerous.
