Piston - Selection

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: View Of Cylinder Bore
Courtesy of FORD MOTOR CO.

NOTE: For precision fit, new pistons are divided into three 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.

Fig 2: Identifying Paint Spot On Piston

Courtesy of FORD MOTOR CO.

Choose the piston with the correct paint color.
- For the procedure, refer to ENGINE - 4.6L AND 5.4L (2V) for Expedition or ENGINE 5.4L (4V) for Navigator.