Master Cylinder Replacement

Remove

Caution: Stored vacuum in the vacuum booster must be pumped down before removing the master cylinder from the vacuum booster. This is necessary to prevent the vacuum booster from sucking in contamination as the master cylinder is removed. This can be done simply by pumping the brake pedal, with the vehicle's engine not running, until a firm feeling brake pedal is achieved.

1. With the engine not running, pump the brake pedal until a firm pedal is achieved.

Master Cylinder Primary And Secondary Brake Tube:

2. Remove the primary and secondary brake tubes from the master cylinder outlet ports. Install plugs in the master cylinder outlet ports.

Caution: Before removing the master cylinder from the vacuum booster, the master cylinder and vacuum booster must be thoroughly cleaned. This must be done to prevent dirt from failing into the vacuum booster.

3. Clean the area where the master cylinder attaches to the vacuum booster. Use only a solvent such as Mopar Brake Parts Cleaner or an equivalent.

Master Cylinder Mounting To Brake Booster:

4. Remove the 2 nuts mounting master cylinder to vacuum booster.
5. Slide the master cylinder straight out of the vacuum booster.

Caution: The master cylinder is used to create the seal for holding vacuum in the vacuum booster. The vacuum seal on the master cylinder MUST be replaced whenever the master cylinder is removed from the vacuum booster.

6. Remove the vacuum seal from the mounting flange of the master cylinder. Do not pry the seal off the master cylinder by inserting a sharp tool between the seal and master cylinder casting.

Install

Caution: When installing the master cylinder on a vehicle, a NEW vacuum seal MUST be installed on the master cylinder.

Vacuum Seal Installed On Master Cylinder:

1. Install a NEW vacuum seal on the master cylinder. Make sure the seal sits squarely in the groove on the master cylinder.

Note: It is not necessary to bleed the entire hydraulic system after replacing the master cylinder, providing that the master cylinder has been filled and bled prior to installation, and the vehicle's brake lines have not been open to the air for an extended period of time.

2. Bleed the master cylinder assembly prior to mounting it on the power brake booster. Refer to Bleeding Master Cylinder for the proper procedure.
3. Position the master cylinder on the studs of the vacuum booster. Be sure the push rod on the vacuum booster is correctly aligned with the piston of the master cylinder.
4. Push the master cylinder up against the front of the vacuum booster.
5. Install the master cylinder to vacuum booster mounting nuts and tighten to a torque of 28 Nm (250 inch lbs.).
6. Connect brake tubes to master cylinder primary and secondary ports. Tighten fittings to a torque of 17 Nm (145 inch lbs.).