Master Cylinder: Inspection

Wash master cylinder body, bore and piston assemblies with denatured or isopropyl alcohol. Inspect piston assemblies and return springs.
Replace pistons if they are scored galled, worn, cracked or broken. Replace springs if they are broken, bent, collapsed, distorted or fatigued.
Inspect tube seat inserts in outlet ports. Replace if they are cracked, scored, loose or cocked. If removal kits are not available, replace by using one of the following methods.
On Bendix: Remove worn tube seat inserts using an easy-out. Thread easy-out firmly into tube seat insert and tap out.
On Delco-Moraine: Drill a 13/64" (5.1 mm) hole through tube seat inserts. Place a heavy washer over outlet and thread a 1/4-20 x 3/4" screw into tube seat insert. Tighten screw until tube seat insert is unseated. Remove check valve and spring from drum brake outlet, if used.
Inspect cylinder bore for scoring, corrosion or wear. Aluminum master cylinders are anodized. Wear on the anodized surface, as evidenced by lighter areas, is normal and not detrimental.
Use crocus cloth to polish out light corrosion on cast iron master cylinders. Replace master cylinder if bore does not clean up using crocus cloth. Aluminum master cylinders may not be polished and must be replaced.
Inspect compensator and by-pass ports at bottom of reservoir. If they are plugged or dirty, clean them using brake cleaning solvent and compressed air only.