GM Service Manual Online
For 1990-2009 cars only

Cleaning Procedure

   ā€¢ 
  • Clean the piston and rings in cleaning solvent. Do not use a wire brush on the piston. Damage may occur.
  •    ā€¢ 
  • Clean the piston ring grooves with a ring groove cleaning tool.
  • Inspection Procedure

       ā€¢ 
  • Inspect the pistons for cracks and scoring.
  •    ā€¢ 
  • Inspect the liner for scratches, cracks, and scoring.
  • Measurement Procedure


      Object Number: 736689  Size: SH
    1. Measure the piston ring groove clearance as follows:
    2. ā€¢ First groove: 0.067-0.105 mm (0.0026- 0.0041 in)
      ā€¢ Service Limit: 0.2 mm (0.0787 in)
      ā€¢ Second and third grooves: 0.03-0.07 mm (0.0012-0.0020 in)
      ā€¢ Service Limit: 0.15 mm (0.0059 in)
      ā€¢ Oil control ring: 0.030-0.07 mm (0.0012-0.0028 in)
      ā€¢ Service Limit: 0.15 mm (0.0059 in)
    3. Measure the piston ring end gap.
    4. Insert the piston assembly into the cylinder liner, 195 mm (7.67 in) below the top of the cylinder liner.

    5. Object Number: 736692  Size: SH
    6. Measure the piston ring gap as follows:
    7. ā€¢ First compression ring: 0.20-0.30 mm (0.0079-0.0118 in)
      ā€¢ Service Limit: 1.2 mm (0.0472 in)
      ā€¢ Second and third compression rings: 0.30-0.45 mm (0.0118-0.0177 in)
      ā€¢ Service Limit: 1.2 mm (0.0472 in)
      ā€¢ Oil control ring: 0.20-0.40 mm (0.079-0.0157 in)
      ā€¢ Service Limit: 1.2 mm (0.0472 in)

      Object Number: 736697  Size: MH
    8. Measure the piston pin bore inside diameter. Measurement should be 40.004-40.012 mm (1.5750-1.5752 in) (1).
    9. Service limit: 40.05


      Object Number: 736695  Size: SH

      Important: Replace the piston pin if it is less than the specification.

    10. Measure the piston pin to the piston clearance. The measurement should be taken at 3 different points. The measurement should not be less than 39.95 mm (1.5728 in).
    11. Subtract the piston pin diameter from the piston pin bore reading. Proper clearance is 0.004-0.017 mm (0.0002-0.0007 in).
    12. Apply a piece of plastic gage the width of the connecting rod bearing journal.
    13. Important: Apply a small amount of molybdenum grease to the bolts.

    14. Install the connecting rod bearing inserts to the connecting rod and the connecting rod cap.
    15. Install the connecting rod bolts.
    16. Tighten
      Tighten the connecting rod bolts to 39 NĀ·m (29 lb ft). Then tighten an additional 60 degrees, and then 30 degrees.

    17. Remove the connecting rod cap from the crankshaft.
    18. Important: Do not remove the plastic gage from the crankshaft journal until the clearance measurement is finished.

    19. Measure the plastic gage.
    20. The measurements should be 0.037-0.076 mm (0.00146-0.00299 in). If the clearances are within factory specifications, the connecting rod bearings are satisfactory.
    21. Remove the plastic gage.
    22. If the clearances are not within the factory specifications, replace the connecting rod bearing inserts as a set (upper and lower inserts).
    23. Repeat the procedure.
    24. If the connecting rod bearings still are not within the specifications, replace the crankshaft.