Method 1: Two-Person Bleeding
1. Gather Supplies: You'll need:
* New brake fluid (DOT 3 or DOT 4, check your owner's manual).
* A clear hose (about 3-4 feet long) that fits snugly over the bleeder valve.
* A container to catch the old brake fluid.
* A wrench that fits your bleeder valves (usually 8mm or 10mm – check your vehicle).
* Rags or shop towels.
* A helper.
2. Locate Bleeder Valves: The bleeder valves are located on each brake caliper (front and rear). They are small, typically hexagonal-shaped fittings.
3. Fill the Master Cylinder: Open the master cylinder reservoir and check the fluid level. Top it off with fresh brake fluid. Keep an eye on the fluid level throughout the bleeding process, as it will decrease as you bleed the brakes. You should never let the reservoir run low.
4. Position Helper: Have your helper sit in the driver's seat. They need to be able to pump the brake pedal. Explain to them explicitly not to pump the pedal continuously. Short, firm pumps are best.
5. Attach Hose and Container: Attach one end of the clear hose to the bleeder valve of the furthest wheel from the master cylinder (usually the rear passenger-side wheel). Place the other end of the hose in the container.
6. Bleeding Process:
* Your helper firmly pumps the brake pedal several times.
* Then, have your helper hold the brake pedal down.
* While the pedal is held down, open the bleeder valve slightly with your wrench. You should see old brake fluid flowing through the hose.
* Close the bleeder valve before your helper releases the brake pedal.
* Repeat this pump-hold-open-close sequence several times until you see clean, clear brake fluid coming out of the bleeder valve with no air bubbles.
7. Move to Next Wheel: Repeat steps 5 & 6 for each wheel, moving from furthest to closest to the master cylinder. The typical order is:
* Rear passenger side
* Rear driver side
* Front passenger side
* Front driver side
8. Check Fluid Level: Throughout the process, monitor the master cylinder's fluid level and add more brake fluid as needed. A low fluid level is a major problem and could lead to air entering the system.
9. Test Brakes: After bleeding all four wheels, have your helper pump the brake pedal a few times to make sure it feels firm. Test the brakes carefully in a safe, open area. If the pedal feels soft or spongy, repeat the bleeding process.
Method 2: Pressure Bleeder
A pressure bleeder makes this process *significantly* easier and more efficient. A pressure bleeder connects to the master cylinder reservoir and maintains consistent pressure, pushing the air out of the system. Follow the manufacturer's instructions for the pressure bleeder, but generally, you'll:
1. Attach Bleeder: Attach the pressure bleeder to the master cylinder.
2. Set Pressure: Set the bleeder to the recommended pressure (usually around 15-20 PSI, check your bleeder's instructions).
3. Open Bleeder Valves: Open each bleeder valve one at a time and allow the fluid to flow freely until no more air bubbles appear.
Important Considerations:
* Safety: Brake fluid is corrosive, so wear gloves and eye protection. Be careful not to spill it on your painted surfaces.
* Air in the System: If you still have a spongy brake pedal after bleeding, you might have air trapped in the ABS system (if your Blazer has ABS), a faulty master cylinder, or other problems. You might need professional assistance in this case.
* New Brake Line: If you just replaced a brake line, carefully check all connections for leaks before and after bleeding the brakes.
If you're uncomfortable performing this task yourself, it's always best to have a qualified mechanic bleed your brakes. Improperly bled brakes are extremely dangerous.
