Piston Inspection

Piston Inspection





1. NOTICE: Do not use a caustic cleaning solution or a wire brush to clean pistons or piston damage may occur.

NOTICE: Extreme care must be used when cleaning piston ring grooves on aluminum pistons or piston damage may occur.

Clean the pistons with liquid soap and water.

2. NOTICE: Do not use the Piston Ring Groove Scraper to clean the 1st compression ring groove or piston damage may occur.

NOTICE: Use the 1st (top) compression ring to clean the top ring groove only. Because the ring grooves are different design, using the wrong compression ring to clean the ring groove will damage the piston.

Break the old 1st (top) compression ring in half, then use the compression ring to clean the piston ring groove area of the piston.





3. Using the Piston Ring Groove Scraper, clean the 2nd compression ring groove and the oil control ring groove in the piston.





4. Inspect the piston ring lands, skirts, oil ring slot corners and pin bosses for scoring, scuffing or cracks. Install a new piston if these types of damage appear.

5. NOTE: Typical piston shown.

Measure the keystone piston ring groove wear.

1. Select 2.685 mm (0.105 in) piston gauge pins.

2. Install the gauge pins in the top groove.

3. Using a 75-100 mm (3-4 in) micrometer, measure the distance between the gauge pins. Install a new piston if not within specification. For additional information, refer to Specifications.





6. Check the side clearance of the intermediate ring groove.
- Place the outer edge of the new ring in its respective ring groove.

- Roll the entire ring around the piston in its groove. Make sure the ring can move freely in its groove.

- Use the Feeler Gauge Set to check the side clearance. Install a new piston if it is not within specifications. For additional information, refer to Specifications.





7. Check the side clearance of the oil control ring groove.
- Place the outer edge of the new ring in its respective ring groove.

- Roll the entire ring around the piston in its groove. Make sure the ring can move freely in its groove.

- Use the Feeler Gauge Set to check the side clearance. Install a new piston if it is not within specifications. For additional information, refer to Specifications.

8. Use a 25-50 mm (1-2 in) micrometer to 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. For additional information, refer to Specifications.





9. Using a 1-2 inch telescoping gauge and a 25-50 mm (1-2 in) micrometer, measure each piston pin bore inside diameter, at 2 locations 90 degrees apart. Record the reading.
- To check the piston pin clearance, subtract the piston pin outside diameter from the piston bore inside diameter. If the clearance exceeds specifications, install a new piston pin and recheck the clearance. For additional information, refer to Specifications.