Piston Selection

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The cylinder bore must be within the specifications for taper and out-of-round before fitting a piston.

Select a piston size based on the cylinder bore.

Fig 1: Identifying Cylinder Bore Measuring Directions
Courtesy of FORD MOTOR CO.

NOTE: For precision fit, new pistons are divided into 3 categories (grade sizes). A paint spot on the new pistons indicates the grade size. Choose the piston with the correct paint color after measuring the cylinder bore diameter.

Choose the piston with the correct paint color.
- Refer to the appropriate ENGINE article for the procedure.
  
  Fig 2: Identifying Piston Grade Size
  Courtesy of FORD MOTOR CO.