Brake Booster

Complete removal and replacement of the brake booster assembly, including master cylinder removal, pushrod disconnection, and vacuum line service.

Warnings

Tools required

Parts

• Brake booster assembly × 1 — Use OEM specification
• Brake master cylinder to booster gasket/seal × 1 — Use OEM specification
• Vacuum check valve (if not included with booster) × 1 — Use OEM specification
• Pushrod clevis pin clip × 1 — Use OEM specification

Fluids

• DOT 3 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground, engage parking brake, and place wheel chocks behind rear wheels
2. Turn ignition off and remove key. Do NOT disconnect battery as this may trigger airbag system faults
3. Open hood and locate brake fluid reservoir. Using turkey baster or syringe, remove as much brake fluid as possible from reservoir and dispose of properly
4. Remove driver's side lower dashboard trim panel to access brake pedal assembly (typically secured with clips and plastic screws)
5. Position brake fluid catch pan under master cylinder area to catch spillage
6. Gather all tools and new parts. Inspect new brake booster for shipping damage and verify vacuum check valve is present
7. Have assistant available for brake bleeding procedure, or prepare pressure/vacuum bleeding equipment

Procedure

1. 1

   Disconnect vacuum line from brake booster
   Locate the vacuum line connection on the brake booster (black rubber hose coming from intake manifold on the 1.5L turbo engine). Carefully disconnect the vacuum line from the booster check valve. Inspect the check valve for damage or deterioration. If check valve remains in the booster, carefully extract it by hand or with pliers, taking care not to damage the booster housing.
   ℹ️The vacuum check valve prevents engine vacuum loss if the booster fails. Always replace if damaged or if valve rattles excessively when shaken.
2. 2

   Disconnect brake lines from master cylinder
   Using appropriate flare nut wrenches (typically 10mm and 12mm), carefully loosen and disconnect both brake lines from the master cylinder. Primary line (front brakes) and secondary line (rear brakes) must both be removed. Immediately cap or plug the brake lines and master cylinder ports to minimize fluid loss and prevent contamination. Allow fluid to drain into catch pan.
   ⚠Use proper flare nut wrenches to prevent rounding the soft brass brake line fittings. Standard open-end wrenches will likely damage the fittings.
   ⚠Brake fluid will continue to drip for several minutes. Keep catch pan in place and protect painted surfaces.
3. 3

   Remove master cylinder from brake booster
   Remove the two master cylinder mounting nuts (12mm) securing the master cylinder to the brake booster studs. Carefully pull the master cylinder straight away from the booster, supporting its weight. Note the position of the master cylinder pushrod and gasket/seal on the booster face. Set master cylinder aside in a clean area where it will not tip over or leak fluid onto components.
   ℹ️Do not allow master cylinder to hang by brake lines. Support the weight fully during removal.
   Torque spec

   Master Cylinder Nuts25 Nm (18 lb-ft)
4. 4

   Disconnect pushrod from brake pedal
   Working from inside the vehicle under the dashboard, locate the pushrod clevis connection to the brake pedal arm. Use a flashlight to clearly see the clevis pin and retaining clip. Remove the retaining clip (may be a cotter pin style or wire clip). Remove the clevis pin that connects the pushrod to the brake pedal. Note the orientation and position for reassembly. The pushrod will now be free from the pedal.
   ⚠️Take a photo or make careful notes of the pushrod-to-pedal connection. Incorrect reassembly can cause brake pedal disconnection while driving.
   ⚠The clevis pin retaining clip may spring away when removed. Work carefully to avoid losing small parts in the confined space.
5. 5

   Remove brake booster mounting nuts
   From the engine bay side, locate and remove the four brake booster mounting nuts (typically 14mm) that secure the booster to the firewall/bulkhead. These nuts are accessed from the engine compartment and thread onto studs that pass through the firewall. Support the booster weight as you remove the final nut.
   ⚠The brake booster is heavy (approximately 10-12 lbs) and awkward to handle. Be prepared to support its weight as the last nut is removed.
   Torque spec

   Brake Booster Nuts25 Nm (18 lb-ft)
6. 6

   Remove brake booster assembly
   Carefully pull the brake booster forward and out of the engine compartment, guiding the pushrod through the firewall opening. You may need to manipulate the angle and rotate slightly to clear surrounding components. Once the pushrod clears the firewall, remove the booster completely. Inspect the firewall mounting surface and clean any debris or corrosion.
   ℹ️The pushrod extends through the firewall into the cabin. Coordinate the removal angle to avoid bending or damaging the rod.
7. 7

   Prepare new brake booster for installation
   Inspect the new brake booster for shipping damage. Verify the pushrod length matches the old unit (critical for proper brake operation). Install the vacuum check valve into the booster port if not pre-installed, ensuring it seats fully and is oriented correctly (flow direction arrow should point toward booster). Install new master cylinder gasket/seal onto the booster mounting face. Compare pushrod clevis adjustment to old unit.
   ⚠️Pushrod length is CRITICAL for safe brake operation. If pushrod length adjustment is required, consult factory service manual for proper measurement procedure. Incorrect length can cause residual brake drag or complete brake failure.
8. 8

   Install new brake booster
   Carefully position the new brake booster into the engine compartment, guiding the pushrod through the firewall opening. Align the mounting studs with the firewall holes. From inside the vehicle, verify the pushrod has passed through cleanly and is accessible at the brake pedal. From the engine bay, hand-start all four mounting nuts onto the studs.
   ℹ️Do not fully tighten nuts yet. All four nuts should be hand-started before torquing to ensure even seating.
9. 9

   Torque brake booster mounting nuts
   Using a torque wrench, tighten the four brake booster mounting nuts in a cross-pattern (opposing nuts) to 25 Nm (18 lb-ft). This ensures even pressure on the booster mounting flange. Verify all four nuts are properly torqued and the booster is seated firmly against the firewall with no gaps.
   ⚠Cross-pattern tightening prevents distortion of the booster mounting flange. Do not fully tighten one nut before starting the others.
   Torque spec

   Brake Booster Nuts25 Nm (18 lb-ft)
10. 10

    Reconnect pushrod to brake pedal
    Working from inside the vehicle, align the pushrod clevis with the brake pedal arm hole. Insert the clevis pin through the pedal arm and clevis. Install the new retaining clip and verify it is fully seated and secure. Test the connection by manually moving the brake pedal slightly to ensure the pin is properly engaged and there is no abnormal play.
    ⚠️The pushrod-to-pedal connection must be absolutely secure. Verify the retaining clip is fully engaged and cannot be pulled off by hand. A failed connection will result in complete brake loss.
    Torque spec

    Brake Pedal Pushrod Lock15 Nm (11 lb-ft)
11. 11

    Install master cylinder
    Verify the new gasket/seal is properly positioned on the brake booster face. Carefully align the master cylinder with the booster mounting studs and pushrod. Slide the master cylinder onto the studs, ensuring the pushrod enters the master cylinder bore correctly. Hand-start both mounting nuts. Torque both nuts in a cross-pattern to 25 Nm (18 lb-ft) using a torque wrench.
    ℹ️The master cylinder must be pressed fully against the booster before tightening nuts. Any gap indicates misalignment or incorrect gasket placement.
    Torque spec

    Master Cylinder Nuts25 Nm (18 lb-ft)
12. 12

    Reconnect brake lines
    Remove the plugs/caps from the brake lines and master cylinder ports. Thread each brake line fitting into the master cylinder by hand first to avoid cross-threading. Once hand-tight, use flare nut wrenches to carefully snug the fittings. Do not overtighten brake line fittings; they should be snug but not excessively tight (typically 13-15 Nm / 10-11 lb-ft).
    ⚠Cross-threading brake line fittings will ruin the master cylinder ports. Always start fittings by hand and ensure smooth threading before using wrenches.
13. 13

    Reconnect vacuum line
    Push the vacuum line firmly onto the brake booster check valve until it seats completely. Verify the connection is secure by attempting to pull the line off with moderate force. The line should not disconnect. Ensure the vacuum line routing does not contact hot engine components or sharp edges that could cause chafing.
    ℹ️A loose vacuum connection will cause poor brake assist and may trigger engine vacuum leaks, affecting performance and fuel economy.
14. 14

    Bleed brake system
    Fill the brake fluid reservoir with fresh DOT 3 brake fluid from a sealed container. Bleed the brake system in the proper sequence (typically RR, LR, RF, LF for this vehicle). Use a brake bleeding kit or assistant. Bleed each wheel until all air is removed and only clean, bubble-free fluid emerges. Tighten each bleeder screw to 13 Nm (10 lb-ft). Maintain reservoir level throughout bleeding process. Final reservoir level should be at MAX line.
    ⚠️Air in brake lines will cause spongy pedal and reduced braking power. Continue bleeding until pedal is firm and no air bubbles appear at any wheel. This may require multiple cycles at each wheel.
    ⚠Never allow the reservoir to run dry during bleeding or additional air will enter the system. Check level frequently.
    Torque spec

    Bleeder Screw13 Nm (10 lb-ft)

Reassembly

1. Reinstall driver's side lower dashboard trim panel, ensuring all clips and fasteners are properly secured
2. Check brake fluid reservoir level and top off to MAX line with fresh DOT 3 brake fluid if needed
3. Verify all brake line connections are dry with no signs of leakage
4. Verify vacuum line connection is secure and properly routed away from hot components
5. Clean any spilled brake fluid from painted surfaces immediately with water

Verification

• With engine off, pump brake pedal several times. Pedal should build firm resistance and hold pressure without slowly sinking
• Start engine. Brake pedal should drop slightly as vacuum assist engages. If pedal does not drop, check vacuum line connection
• With engine running, apply firm brake pressure and hold for 30 seconds. Pedal should remain firm and not sink toward floor
• Visually inspect all brake line connections for leaks while assistant applies brake pressure. Check master cylinder mounting area for fluid seepage
• Test drive vehicle in safe, low-traffic area at low speeds (under 15 mph). Verify normal brake operation, firm pedal feel, and straight-line stopping without pulling
• After initial test drive, recheck all connections and inspect for leaks. Check reservoir level
• Perform multiple moderate-force stops from 30-40 mph in a safe area to verify full braking performance before returning to normal driving
• Monitor brake pedal feel for first 100 miles. Any change in pedal height, firmness, or stopping power requires immediate inspection

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle