Master Cylinder - Except Dual Diagonal System: Inspection

On cast iron master cylinders, inspect cylinder bore for scoring or corrosion. Staining on cast iron master cylinders which has not pitted or roughened the surface can be removed with crocus cloth. Move cloth in circular manner. Never polish cylinder with lengthwise strokes. If cylinder is scored, corroded or pitted, replacement is recommended.

On aluminum master cylinders, the body of the master cylinder is anodized. Some signs of bore wear on the anodized surface is normal. This will appear as lighter areas in the anodized surface. If cylinder bore is heavily worn or scored, replace master cylinder.