Where Is the Master Cylinder Located?

Reviewed by

Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on September 5th, 2025

Reading Time: 2 minutes
Summary
  • The master cylinder is usually located on the driver side of the engine bay, mounted to the firewall near the brake pedal and typically positioned below the brake fluid reservoir. In vehicles with power-assisted brakes, it’s attached to the brake booster.
  • It converts brake pedal force into hydraulic pressure, using a piston and dual chambers to apply the brake pads or shoes and slow the vehicle.
  • Safe access requires precautions, including wearing protective gear, carefully disconnecting brake lines and sensors, and unbolting the cylinder from the booster without damaging connected components
Master cylinder with brake fluid reservoir mounted to the brake booster on the driver side of the engine bay | Image Source: Richard McCuistian

The master cylinder is usually found on the driver side of the engine bay, fixed to the firewall near the brake pedal. It typically sits below the brake fluid reservoir. In cars with power-assisted brakes, the master cylinder might be connected to the brake booster.

The master cylinder is just about always mounted to the front side of a vacuum or hydraulic booster that applies pressure to the master cylinder’s piston. That booster is activated by a push rod connecting to the brake pedal.

The brake master cylinder turns the brake pedal’s force into hydraulic pressure that applies the brake linings, whether they be shoes or pads, generating friction that slows down your car. In a way, the cylinder is like the heart of the brakes.

Inside the brake cylinder are two separate chambers and a piston that moves through the chambers.

Tips on How to Access the Master Cylinder

Close-up of the brake master cylinder and fluid reservoir | Image Source: Richard McCuistian

Always wear protective gear when accessing the master cylinder. Put on work gloves to protect your bare skin from direct contact with brake fluid. Wear protective eyewear to keep your eyes safe from injury caused by exposure to brake fluid, fumes, and other hazards.

  1. Using a tool of your choice, draw the fluid out of the master cylinder.
  2. Disconnect the brake lines from the master cylinder using line wrenches.
  3. Disconnect the fluid level sensor connector.
  4. Remove the nuts at the flanges holding the master cylinder to the booster.
  5. Remove the master cylinder.

Exert care when disconnecting the brake lines and working on the brake line clamps. The brake lines might crack if handled roughly, leading to a brake fluid leak. You’ll need to replace a damaged line before replacing the master cylinder.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

Share
Published by
CarParts.com Research Team and Richard McCuistian, ASE Certified Master Automobile Technician