GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 1998 🢒 SL1/SC1/SW1 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Master Cylinder Overhaul

Disassembly Procedure

    Object Number: 866570 Size: SH

    Important: The reservoir cap and the diaphragm can be removed and inspected without removing the master cylinder from the vehicle.

  1. Remove the master cylinder from the vehicle. Refer to Master Cylinder Replacement or Brake Modulator/Master Cylinder Assembly Replacement .

    2. Important: Base brake master cylinder shown. ABS master cylinder procedure is similar.

  2. Wipe the reservoir cap clean.
  3. Remove the cap and inspect the reservoir cap and diaphragm for the following conditions:
    4. • Cuts
    • Cracks
    • Nicks
    • Deformation
    • Replace any damaged parts.
  4. Empty the brake fluid from the reservoir.

    5. Object Number: 866600 Size: SH
  5. Remove the brake fluid level switch.
  6. Remove the reservoir. Refer to Master Cylinder Reservoir Replacement .

    7. Notice: Be careful not to damage piston, bore, or retainer groove.

  7. Remove the retainer clip from the end of the master cylinder while depressing the primary piston assembly. Use a wooden dowel to depress the piston assembly.

    8. Object Number: 872264 Size: SH
  8. Apply low-pressure, non-lubricated compressed air into the upper brake fluid output port at the blind end of the master cylinder bore. This will facilitate the removal of the primary piston assembly, the secondary piston with seals, as well as the spring and spring retainer.
  9. Clean all parts in clean, denatured alcohol. Dry with unlubricated, low-pressure compressed air. Blow out all passages in the cylinder body.
  10. Inspect the following:
    11. • The pistons and seals for nicks, cuts, cracks, wear, or corrosion. Replace all worn or damaged parts.
    • The master cylinder bore for scoring or corrosion. If noted, replace master cylinder. Do not hone the master cylinder bore. Also, no abrasives should be used in the bore.

Assembly Procedure

    Object Number: 872262 Size: SH
  1. Lubricate the secondary seal with clean brake fluid.
  2. Lubricate the master cylinder bore with clean brake fluid.
  3. Install the spring into master cylinder bore.
  4. Install the secondary piston assembly into the master cylinder bore.
  5. Lubricate the primary seal with clean brake fluid.
  6. Lubricate the master cylinder bore with clean brake fluid.
  7. Install the primary piston assembly into the master cylinder bore.

    8. Object Number: 866588 Size: SH
  8. Install the retainer clip, while depressing teh primary piston assembly Use a wooden dowel to depress piston assembly.
  9. Install the reservoir. Refer to Master Cylinder Reservoir Replacement .
  10. Install the brake fluid level switch.
  11. Install the master cylinder into the vehicle. Refer to Master Cylinder Replacement or Brake Modulator/Master Cylinder Assembly Replacement .