Clutch Release Cylinder: Inspection

Check the clutch release cylinder for fluid leakage.
Check the clutch release cylinder boots for damage.
Check the release cylinder bore for rust and damage.
Measure the release cylinder bore at three locations (bottom, middle and top) with a cylinder gauge and replace the release cylinder assembly if the bore-to-piston clearance to exceeds the limit.
1. Clearance to piston limit: 0.15 mm (0.006 in.)
  
  Fig 1: Measuring The Release Cylinder Bore
  Courtesy of KIA MOTORS AMERICA, INC.