Brake Booster

This procedure covers the removal and replacement of the brake booster assembly on a 2017 Maserati Levante 3.0L V6 Twin Turbo RWD, including master cylinder removal, vacuum line disconnection, and brake system bleeding.

Warnings

Tools required

Parts

• Brake booster assembly × 1 — Use OEM specification
• Brake booster gasket/seal × 1 — Use OEM specification
• Master cylinder to booster O-ring × 1 — Use OEM specification
• Vacuum check valve (if damaged) × 1 — Use OEM specification
• Brake line crush washers × 4 — Use OEM specification

Fluids

• DOT 4 Racing Brake Fluid — 1.5 qt

Preparation

1. Park vehicle on level ground and apply parking brake firmly. Place wheel chocks behind rear wheels.
2. Disconnect negative battery terminal and wait 15 minutes for airbag system capacitors to discharge before working near steering column.
3. Open brake fluid reservoir and use turkey baster or fluid extractor to remove as much fluid as possible. Dispose of old fluid properly.
4. Remove driver's side lower dashboard trim panels and knee bolster to access brake pedal assembly from inside cabin.
5. Cover driver's seat, floor carpet, and steering column with plastic sheeting to protect from brake fluid spills.
6. Take photos of all brake line connections and vacuum line routing for reference during reassembly.
7. Ensure you have adequate lighting to see into the tight space behind the brake pedal assembly.

Procedure

1. 1

   Disconnect vacuum line from brake booster
   Locate the vacuum supply line connected to the brake booster (large hose coming from intake manifold). Squeeze the retaining clip and carefully pull the vacuum line straight off the booster fitting. Inspect the check valve in the line for damage or debris; replace if necessary. Cap the line temporarily to prevent vacuum leaks.
2. 2

   Remove master cylinder mounting nuts
   Working from the engine bay, locate the two nuts securing the master cylinder to the front of the brake booster. Use a socket wrench to remove both mounting nuts completely. Do not allow the master cylinder to hang by the brake lines.
   ⚠The master cylinder is heavy and filled with brake fluid. Support it carefully to prevent damage to brake lines.
   Torque spec

   Master Cylinder Nuts25 Nm (18 lb-ft)
3. 3

   Disconnect brake lines from master cylinder
   Using a line wrench (not standard wrench), carefully loosen the two brake line fittings at the master cylinder. Have a catch pan ready as fluid will drain. Once loose, unthread the lines by hand and immediately cap or plug all openings to prevent fluid loss and contamination. Carefully move the master cylinder aside, supporting it on the engine bay structure with wire or a strap.
   ⚠️Use only a proper line wrench to avoid rounding off the soft brass fittings. Damaged fittings can cause brake fluid leaks and system failure.
   Torque spec

   Line Fittings22 Nm (16 lb-ft)
4. 4

   Disconnect brake pedal pushrod from brake pedal
   From inside the cabin, locate the pushrod connecting the brake booster to the top of the brake pedal arm. You will see a clevis pin secured by a lock clip or cotter pin. Remove the retaining clip, then drive out the clevis pin using a pin punch. The pushrod should now be disconnected from the pedal arm. Note the orientation and any adjustment spacers present.
   ⚠Work space is extremely tight. Use a flashlight and mirror to clearly see the connection. Take photos before disassembly.
   Torque spec

   Brake Pedal Pushrod Lock15 Nm (11 lb-ft)
5. 5

   Remove brake booster mounting nuts from firewall
   From inside the cabin, locate the four nuts securing the brake booster to the firewall. These are typically accessed from behind the brake pedal assembly. Use a socket wrench with extension to remove all four mounting nuts. Keep track of any spacers or washers on the studs.
   ⚠The brake booster is heavy and may fall once the last nut is removed. Have an assistant support the unit from the engine bay.
   Torque spec

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

   Remove brake booster assembly from vehicle
   Working from the engine bay, carefully pull the brake booster assembly forward off the firewall studs. Maneuver it out of the engine compartment, being careful not to damage surrounding components. Inspect the firewall mounting surface and studs for damage or corrosion.
7. 7

   Prepare new brake booster for installation
   Remove the new brake booster from packaging and verify it matches the original unit exactly (stud spacing, vacuum port location, pushrod length). Install the new firewall gasket/seal onto the rear of the booster. Verify the pushrod length matches the original or consult service manual for proper adjustment procedure. Apply a light coat of silicone brake grease to the master cylinder mounting surface O-ring.
   ⚠Incorrect pushrod length will cause improper brake pedal height and may result in brake drag or inadequate braking force.
8. 8

   Install new brake booster to firewall
   From the engine bay, carefully position the new brake booster onto the firewall studs, ensuring the gasket is properly seated. Have an assistant guide the pushrod through the firewall opening from inside the cabin. Align all four studs with the mounting holes. From inside the cabin, hand-thread all four mounting nuts onto the studs, then torque in a cross pattern to specification using a torque wrench.
   ⚠️Follow cross-pattern tightening sequence to ensure even mounting pressure. Uneven torque can cause booster misalignment and vacuum leaks.
   Torque spec

   Brake Booster Nuts25 Nm (18 lb-ft)
9. 9

   Reconnect brake pedal pushrod to brake pedal
   From inside the cabin, align the pushrod clevis with the hole in the brake pedal arm. Insert the clevis pin and secure it with a new retaining clip or cotter pin. Ensure the connection is secure and the pin cannot back out. Verify smooth pedal movement through its full range without binding.
   Torque spec

   Brake Pedal Pushrod Lock15 Nm (11 lb-ft)
10. 10

    Install master cylinder to brake booster
    Install a new O-ring onto the master cylinder mounting surface. Carefully position the master cylinder onto the brake booster studs, ensuring the pushrod properly engages the master cylinder piston (you should feel slight resistance). Hand-thread both mounting nuts, then torque to specification in an even, alternating pattern.
    ⚠Ensure the pushrod is properly seated in the master cylinder piston bore before tightening nuts. Misalignment can damage internal components.
    Torque spec

    Master Cylinder Nuts25 Nm (18 lb-ft)
11. 11

    Reconnect brake lines to master cylinder
    Install new crush washers on both brake line fittings. Carefully thread the brake lines into the master cylinder ports by hand, ensuring they are not cross-threaded. Using a line wrench and torque wrench, tighten both fittings to specification. Double-check that fittings are fully seated and properly torqued.
    ⚠️Improperly torqued line fittings will leak under pressure, causing brake failure. Use a calibrated torque wrench and line wrench.
    Torque spec

    Line Fittings22 Nm (16 lb-ft)
12. 12

    Reconnect vacuum line to brake booster
    Remove the temporary cap from the vacuum supply line. Inspect the check valve orientation (arrow should point toward booster). Push the vacuum line firmly onto the booster fitting until you hear/feel the retaining clip engage. Tug gently to verify secure connection.
13. 13

    Fill and bleed brake system
    Fill the brake fluid reservoir with fresh DOT 4 Racing Brake Fluid from a sealed container. Use a pressure bleeder or two-person manual bleeding method to bleed all four wheels in the correct sequence (typically RR, LR, RF, LF for RWD, but verify in service manual). Bleed until all air is removed and only clean, bubble-free fluid exits each bleeder. Keep reservoir topped off during entire bleeding process. Torque bleeder screws to specification when complete.
    ⚠️Air in the brake system will cause partial or complete brake failure. Continue bleeding until absolutely no air bubbles are present in the fluid.
    ⚠Never let the reservoir run dry during bleeding or you will introduce more air into the system.
    Torque spec

    Bleeder Screw14 Nm (10 lb-ft)
14. 14

    Check for leaks and verify vacuum assist
    Reconnect the negative battery terminal. Start the engine and immediately check all brake line connections and master cylinder mounting area for any signs of fluid leakage. With engine running, pump the brake pedal several times and hold firm pressure—the pedal should feel solid with no sinking. Turn off the engine and pump the pedal until the vacuum assist is depleted (pedal becomes harder), then start the engine—the pedal should drop slightly as vacuum assist engages, confirming proper booster operation.
    ⚠️Any brake fluid leakage requires immediate correction before the vehicle is driven. Do not proceed if leaks are present.

Reassembly

1. Reinstall all interior trim panels, knee bolster, and dashboard components removed during disassembly.
2. Remove protective plastic sheeting from driver's seat and cabin area.
3. Verify brake pedal height and free play are within factory specifications (consult service manual for exact measurements).
4. Top off brake fluid reservoir to MAX line with fresh DOT 4 Racing Brake Fluid and securely install reservoir cap.

Verification

• With engine running, verify firm brake pedal with no sponginess or excessive travel. Pedal should not sink under sustained pressure.
• Perform a visual inspection of all brake line connections, master cylinder mounting area, and booster vacuum line for any signs of fluid or vacuum leaks.
• Test vacuum booster function: pump brake pedal with engine off until hard, then start engine. Pedal should drop 1-2 inches as vacuum assist engages.
• Perform a controlled low-speed brake test in a safe area (empty parking lot) at 5-10 mph to verify proper braking function before normal driving.
• Check for any unusual noises, vibrations, or pedal pulsations during brake application.
• Road test vehicle at gradually increasing speeds, verifying straight-line braking with no pull to either side and adequate stopping power.
• After 50-100 miles of driving, re-inspect all connections for leaks and verify brake fluid level has not dropped, which would indicate a leak or incomplete bleeding.
• If any abnormality is detected (soft pedal, leaks, pulling, noise), do NOT drive the vehicle and seek professional assistance immediately.

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