GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Generic 🢒 2002 🢒 Unit Repair 🢒 Engine 🢒 Engine Mechanical - 5.0L and 5.7L 🢒 Piston, Connecting Rod, and Bearing Cleaning and Inspection

    Object Number: 34671 Size: SH

    Caution: Wear safety glasses in order to avoid eye damage.

    Important: Measurement of all the components should be taken with the components at room temperature.

    Do not use a wire brush in order to clean any part of the piston.

  1. Clean the piston and connecting rod in cleaning solvent.
  2. Dry the components with compressed air.

    3. Object Number: 4977 Size: SH
  3. Clean the piston ring grooves with a suitable ring groove cleaning tool.

    4. Object Number: 156168 Size: SH
  4. Clean the piston oil lubrication holes and slots.
  5. Inspect the piston for the following:
    6. • Eroded areas (1) on the top of the piston
    • Scuffed or damaged skirt (2)
    • Damage to the piston pin bore (3)
    • Cracks in the piston ring lands, the piston skirt, or the piston pin bosses
    • Piston ring grooves for nicks, burrs, or other warpage which may cause the piston ring to bind.
  6. Inspect the piston pin for scoring, wear or other damage.

    7. Object Number: 4969 Size: SH
  7. Measure the piston ring-to-piston ring groove side clearance.
    8. 7.1. Insert the edge of the piston ring into the piston ring groove.
    7.2. Roll the piston ring completely around the piston.
       • If binding is caused by a distorted piston ring groove, MINOR imperfections may be removed with a fine file.
       • If binding is caused by a distorted piston ring, then replace the piston ring.

    Object Number: 22934 Size: SH
  8. Measure the piston ring side clearance with a feeler gauge.
    9. • If the piston ring side clearance is too small, try another piston ring set.
    • If the proper piston ring-to-piston ring groove clearance cannot be achieved, replace the piston and pin assembly.
  9. To determine the proper piston ring side clearance, refer to Engine Mechanical Specifications.

    10. Object Number: 4976 Size: SH
  10. To determine piston pin-to-bore clearance use a micrometer and measure the piston pin.

    11. Object Number: 4975 Size: SH
  11. To determine piston pin-to-bore clearance, use an inside micrometer and measure the piston pin bore.
  12. To determine the piston pin-to-bore clearance, subtract the piston pin diameter from the piston pin bore diameter. Refer to Engine Mechanical Specifications.

    13. Object Number: 188016 Size: SH
  13. Measure the piston with a micrometer at a right angle to the piston pin bore, measure the piston at 11 mm (0.433 in) from the bottom of the skirt, refer to Engine Mechanical Specifications.

    14. If the piston is not within specifications, then replace the piston and piston pin as an assembly.


    Object Number: 156167 Size: SH
  14. Inspect the connecting rod for an out-of-round bearing bore. Refer to Engine Mechanical Specifications.

    15. Object Number: 156169 Size: SH
  15. Inspect the connecting rod for twisting.
  16. Inspect the connecting rod for damage to the connecting rod bolt threads.

    17. Object Number: 4968 Size: SH
  17. Measure the piston compression ring end gap.

    18.         Important: Fit each piston compression ring to the cylinder in which it will be used.

    17.1. Place the piston compression ring into the cylinder bore.
    17.2. Push the piston compression ring into the cylinder bore to approximately 6.5 mm (0.25 in) above the piston ring travel.

    The piston ring must be square to the cylinder wall.

    17.3. Use a feeler gage in order to measure the piston ring end gap. Refer to Engine Mechanical Specifications.

    Select another size piston ring set if the piston ring end gap exceeds specifications.