GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 8037 Ring Compressor
    • J 8087 Cylinder Bore Gage
    • J 45059 Angle Meter

Important: Powdered metal connecting rods and rod bearing caps are NOT interchangeable, and must be assembled with the mating surfaces properly oriented and aligned. Piston, piston pin, and connecting rod are to be serviced as an assembly.

Piston Selection


    Object Number: 4972  Size: SH

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

    For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.

    A used piston and piston pin set may be reinstalled if, after cleaning and inspection, the piston and piston pin are within specifications.

  1. Use the J 8087 in order to measure the cylinder bore diameter. Measure at a point 64 mm (2.5 in) from the top of the cylinder bore and 90 degrees to the crankshaft centerline.

  2. Object Number: 4974  Size: SH
  3. Measure the J 8087 with a micrometer and record the reading.

  4. Object Number: 188016  Size: SH
  5. With a micrometer or caliper at a right angle to the piston pin bore, measure the piston 11 mm (0.433 in) from the bottom of the skirt.
  6. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance. Refer to Engine Mechanical Specifications .
  7. If the proper clearance cannot be obtained, then select another piston and measure the clearances.
  8. If the proper fit cannot be obtained, the cylinder bore may require honing or boring.

  9. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation into the proper cylinder.

Installation Procedure

  1. Apply clean engine oil to the following components:
  2. • The piston
    • The piston rings
    • The cylinder bore
    • The bearing surfaces

    Object Number: 480573  Size: SH
  3. Install the J 8037 onto the piston and compress the piston rings.

  4. Object Number: 1792310  Size: SH

    Important: When assembled, the following reference marks must be addressed; the reference mark on top of the piston (1) must face the front of the engine block. The dimple on the connecting rod (2) must face the front of the engine block on cylinders 2, 4, and 6, and towards the rear of the engine block on cylinders 1, 3, and 5. Wrap a clean, lint free towel around the connecting rod ends when installing the piston into the cylinder so as not to damage the crankshaft journals or cylinder bore.

  5. Check reference marks prior to installation into the block.

  6. Object Number: 909623  Size: SH
  7. Install the piston and connecting rod assembly, and the J 8037 into the proper cylinder bore.

  8. Object Number: 5159  Size: SH
  9. Use the J 8037 and lightly tap the top of the piston with a wooden hammer handle.
  10. Hold the J 8037 firmly against the engine block until all of the piston rings have entered the cylinder bore.

    Notice: Refer to Fastener Notice in the Preface section.

    Important: The connecting rods and rod bearing caps are NOT interchangeable. Reference the match marks on the connecting rods and the connecting rod bearing caps made in the removal procedure to ensure that they are assembled in their original position and direction, with the connecting rod/rod bearing cap mating surfaces properly oriented and aligned.


    Object Number: 1360214  Size: SH
  11. Install the connecting rod bearing, cap, and bolts.
  12. Tighten

    1. Tighten the bolts evenly on the first pass to 20 N·m (15 lb ft).
    2. Use the J 45059 in order to tighten the bolts on the final pass an additional 100 degrees.

    Object Number: 5163  Size: SH
  13. After the piston and connecting rod assemblies have been installed, lightly tap each connecting rod assembly, parallel to the crankpin, in order to ensure that the connecting rods have side clearance.
  14. Use a feeler gage or a dial indicator to measure the connecting rod side clearance between the connecting rod caps. The connecting rod side clearance should be 0.15-0.44 mm (0.006-0.017 in).