Piston: Testing and Inspection
Piston InspectionSpecial Tool(s):
Inspection
1. 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.
Clean the pistons with liquid soap and 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 each ring groove will damage the piston.
Break the old compression rings in half, then use the compression rings to clean the piston ring groove areas of the piston.
3. Inspect the piston ring lands, skirts, oil ring slot corers and pin bosses for scoring, cuffing or cracks. Install a new piston if these types of damage appear.
4. Measure the keystone piston ring groove wear.
1 Select 2.08 mm (0.082 inch) piston gauge pins.
2 Install the gauge pins in the top groove.
3 Using a micrometer, measure the distance between the gauge pins. Install a new piston if not within specification.
5. Measure the piston pin diameter in 2 directions at the points shown. Verify the diameter is within specification.
^ If out of specification, install a new piston pin.
6. Measure the outside diameter of the piston pin and the inside diameter of the piston pin bore. The difference between the 2 readings is the piston pin-to-bore clearance. Install a new piston pin or piston if not within specification.
