GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • KM-470-B Angular Torque Gage
    • J 45059 Angle Meter

Piston Inspection

    Caution: Refer to Safety Glasses Caution in the Preface section.


    Object Number: 1241710  Size: SH
  1. Inspect the connecting rod for bending or twisting. If the connecting rod is bent or twisted, replace the connecting rod.
  2. Inspect the connecting rod bearings.
  3. Inspect the connecting rod lower end for wear.
  4. Inspect the connecting rod upper end for scoring.
  5. Inspect the crankshaft rod bearing journal for wear. Refer to Engine Mechanical Specifications .
  6. Inspect the piston for scoring, cracks, and wear.
  7. Inspect the piston for taper using a micrometer.

  8. Object Number: 1241742  Size: SH
  9. Inspect the piston for fit to the connecting rod.

  10. Object Number: 1241734  Size: SH
  11. Inspect the engine block deck surface for flatness using a straight edge and a feeler gage. Refer to Engine Mechanical Specifications .
  12. Inspect the bearing bore for concentricity and alignment using a bore gage. Refer to Engine Mechanical Specifications . If beyond specifications, replace the engine block.
  13. Inspect the engine block cylinder bore for wear, runout, ridging, and taper using a bore gage. Refer to Engine Mechanical Specifications .
  14. Inspect the engine block cylinder bore for glazing.

Connecting Rod Inspection

    Caution: Refer to Safety Glasses Caution in the Preface section.


    Object Number: 1241455  Size: SH
  1. Coat the connecting rod bearings with engine oil.
  2. Important: Grease the connecting rod journals and lubricate the connecting rod bearings slightly so that the plastic gaging thread does not tear when the connecting rod bearing caps are removed.

  3. Install the upper connecting rod bearings into the connecting rod journals.
  4. Install the lower connecting rod bearings into the connecting rod bearing caps.
  5. Measure all of the connecting rod bearing clearances using a commercial available plastic gaging, ductile plastic threads.
  6. Cut the plastic gaging threads (1) to the length of the bearing width. Lay them axially between the connecting rod journals and the connecting rod bearings.
  7. Install the connecting rod bearing caps.
  8. Notice: Refer to Fastener Notice in the Preface section.

  9. Install the connecting rod bearing cap bolts.
  10. Tighten

        • Tighten the connecting rod bearing cap bolts to 25 N·m (18 lb ft).
        • Using the KM-470-B  (1), tighten the connecting rod bearing cap bolts another 30 degrees plus 15 degrees.
  11. Remove the connecting rod bearing caps.
  12. Measure the width of the flattened plastic thread of the plastic gaging (1) using the scale printed on the plastic gaging package. Plastic gaging is available for different tolerance ranges.
  13. Inspect the bearing clearance for permissible tolerance ranges. Refer to Engine Mechanical Specifications .