Piston - Selection

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. 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
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 - 3.9L & 4.2L for the procedure.

Fig 2: Identifying Piston Paint Marking

Courtesy of FORD MOTOR CO.