Piston - Selection

WARNING: This page is about a different car, the 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Ford Crown Victoria. 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: Measuring Cylinder Bore In Two Directions
Courtesy of FORD MOTOR CO.

NOTE: For precision fit, new pistons are divided into three categories within each size range based on their relative position within the range. A paint spot on the new pistons indicates the position within the size range.

Choose the piston with the correct paint color.
- Refer to ENGINE 4.6L 2V or ENGINE 4.6L 4V .
  
  Fig 2: Identifying Paint Spot On New Pistons
  Courtesy of FORD MOTOR CO.