Core Plug Replacement: Material

All core plugs 

NOTE: Cylinder block core plug shown in illustration, cylinder head core plug similar.
Fig 1: Removing Core Plug Using Slide Hammer
Courtesy of FORD MOTOR CO.
1. Use the Slide Hammer and a freeze plug remover to remove the core plug.
NOTE: Oversize plugs are identified by the OS stamped in the flat located on the cup side of the plug.
2. Inspect the core plug bore for any damage that would interfere with the correct sealing of the plug. If the core plug bore is damaged, bore for the next oversize plug.

   Cup-type 

NOTE: Use care during this procedure so as not to disturb or distort the cup sealing surface.
NOTE: When installed, the flanged edge must be below the chamfered edge of the bore to effectively seal the bore.
Fig 2: View Of Cup-Type Core Plug
Courtesy of FORD MOTOR CO.
3. Coat the cup-type core plug and bore lightly with sealant and install the core plug using a freeze plug installer.

   Expansion-type 

NOTE: Do not contact the crown when installing an expansion-type core plug. This could expand the plug before seating and result in leakage.
Fig 3: View Of Expansion-Type Cylinder Block Core Plug
Courtesy of FORD MOTOR CO.
4. Coat the expansion-type core plug and bore lightly with sealant and install the core plug using a freeze plug installer.