Piston Pin to Bore Diameter

WARNING: Cover the end of the pin bore with a hand or shop rag when removing the retainer ring, since it has a tendency to spring out. Wear eye protection. Failure to follow instructions may result in personal injury.

NOTE: Piston and piston pins are a matched set and should not be interchanged.

Fig 1: Identifying Piston Pin Retainer Ring

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Directions For Measuring Piston Pin Bore Diameter

Courtesy of FORD MOTOR CO.

Measure the piston pin bore diameter in 2 directions on each side. Verify the diameter is within specification.
- If out of specification, install new components as necessary. Refer to ENGINE - 3.9L AND 4.2L article for the procedure.