Bleeding air out of a new brake master cylinder is crucial to ensure proper brake system function. The process typically involves bench bleeding the master cylinder before installing it in the vehicle.
Caution: DO NOT allow brake fluid to contact painted surfaces as the fluid damages paint. If contact occurs, immediately flush the affected area with water.
Here are the detailed steps to bleeding air from a master cylinder:
Tools and Materials Needed:
- Bench bleeding kit (usually included with a new master cylinder)
- Brake fluid (type specified for your vehicle)
- A bench vise (optional but helpful)
- A catch container for brake fluid
Steps for Bench Bleeding Air from the Master Cylinder:
- Mount the Master Cylinder:
- Secure the master cylinder in a bench vise if available. If not, ensure it is held steady on a workbench.
- Install Bleeder Kit:
- Attach the plastic fittings and hoses from the bench bleeding kit to the master cylinder’s brake line ports. Ensure the hoses are submerged in brake fluid within the reservoir to prevent air from being drawn back into the system.
- Fill the Reservoir:
- Fill the master cylinder reservoir with brake fluid. Use the fluid type specified by the vehicle manufacturer.
- Bleed the Master Cylinder:
- Using a screwdriver or similar tool, gently push the master cylinder piston inward. Do this slowly to avoid creating air bubbles.
- Release the piston slowly and allow it to return to its original position.
- Repeat this process several times, watching the hoses for air bubbles. Continue until no more air bubbles are visible in the hoses.
- Check for Air:
- Ensure all air has been purged from the master cylinder. If necessary, gently tap the sides of the master cylinder to dislodge any trapped air bubbles and repeat the bleeding process.
- Seal and Prepare for Installation:
- Once the bleeding process is complete and no air bubbles are visible, remove the hoses and fittings from the master cylinder ports.
- Plug or cap the ports immediately to prevent air from re-entering the master cylinder.
Installing the Master Cylinder in the Vehicle:
- Mount the Master Cylinder:
- Install the master cylinder onto the vehicle’s brake booster or firewall, securing it with the appropriate bolts.
- Connect Brake Lines:
- Reattach the brake lines to the master cylinder ports. Ensure the connections are tight to prevent leaks.
- Final Bleeding:
- Once the master cylinder is installed, you may need to bleed the entire brake system to remove any remaining air. This is typically done by bleeding each wheel’s brake caliper or wheel cylinder, starting with the one farthest from the master cylinder and working your way closer.
Bleeding Air Tips:
- Safety First: Always wear safety glasses and gloves when working with brake fluid, as it is corrosive and can damage paint and skin.
- Cleanliness: Keep the master cylinder and brake fluid clean. Contaminants can cause brake system malfunctions.
- Follow Manufacturer’s Instructions: Always refer to the vehicle’s service manual for specific procedures and specifications related to your particular make and model.
Finally
By following these steps, you can effectively bleeding air out of a new brake master cylinder and ensure proper brake system function.
