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General Procedures: Piston: Inspection

WARNING: This page is about a different car, the 2003 Ford RV Cutaway, 2003 Ford Econoline, 2003 Ford E550 Super Duty, 2003 Ford E450 Super Duty, and 2003 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
    CAUTION: Do not use a caustic cleaning solution or a wire brush to clean pistons.
    CAUTION: Extreme care must be used when cleaning piston ring grooves on aluminum pistons.
  1. Clean pistons with liquid soap and warm water.
  2. NOTE: Use the top compression ring to clean the top ring groove and the bottom compression ring to clean the bottom ring groove. Because the ring grooves are different designs, using the wrong compression ring to clean the wrong ring groove will damage the piston.
  3. Break the old compression rings in half, then use the compression rings to clean the piston ring groove areas of the piston.
  4. Inspect the piston ring lands, skirts, oil ring slot corners and pin bosses for scoring, scuffing or cracks. Inspect the lower inner portion of the piston ring grooves for a high step. Install new piston if any show these types of damage.
  5. Using the special tool and an outside micrometer, measure the keystone piston ring groove wear of the top compression ring. If any of the measurements do not meet specification, install a new piston.
    Fig 1: Measuring Keystone Piston Ring Groove Wear Of Top Compression Ring
    G01537568Courtesy of FORD MOTOR CO.
  6. Using a feeler gauge, measure the intermediate compression ring and the oil control ring side clearance between the ring and ring land.
  7. Measure the outside diameter of the piston pin and the inside diameter of the piston pin bore. The difference between the two readings is the piston pin-to-bore clearance. Install new any piston pin or piston not within specification.
    Fig 2: Identifying Outside Diameter Of Piston Pin And Inside Diameter Of Piston Pin Bore
    G01537569Courtesy of FORD MOTOR CO.