Piston, Connecting Rod, and Bearings Cleaning and Inspection

WARNING: This page is about a different variant/trim than selected.

Clean the deposits from the following components:
- Connecting rod and bearings
- Piston
- Piston pin
Fig 1: Areas Of Connecting Rod, Piston & Piston Pin To Clean
Courtesy of GENERAL MOTORS CORP.
Inspect the piston for the following conditions:
- Scoring on the piston skirt (2)
- Scoring in the piston pin area (3)
- Cracks (1)
- Broken ring groove lands
Fig 2: Identifying Piston Damage Inspection Areas
Courtesy of GENERAL MOTORS CORP.
Measure the piston ring end gap.

Fig 3: Measuring Piston Ring End Gap
Courtesy of GENERAL MOTORS CORP.
- Use a piston to square the piston ring near the top of the cylinder.
- Use a feeler gauge to measure the piston ring gap.
- The 1st compression ring production gap is 0.30-0.45 mm (0.0118-0.0177 in) and the service limit is 1.37 mm (0.0539 in).
- The 2nd compression ring production gap is 0.50-0.65 mm (0.0197-0.0256 in) and the service limit is 1.35 mm (0.0531 in).
- The oil ring production gap is 0.15-0.35 mm (0.0059-0.0138 in) and the service limit is 1.20 mm (0.0472 in).
- Replace the piston ring if the measured value exceeds the service limit.
Measure the piston ring to piston ring groove clearance.
- Use a feeler gauge to measure the clearance between the piston ring and the piston ring groove at several points around the piston.
  
  Fig 4: Measuring Piston Ring Side Clearance
  Courtesy of GENERAL MOTORS CORP.
- The 1st compression ring production clearance is 0.08-0.17 mm (0.0030-0.0007 in) and the service limit is 0.26 mm (0.0102 in).
- The 2nd compression ring production clearance is 0.01-0.03 mm (0.0004-0.0012 in) and the service limit is 0.10 mm (0.0039 in).
- The oil ring production clearance is 0.01-0.03 mm (0.0004-0.0012 in) and the service limit is 0.12 mm (0.0047 in).
- Replace the piston ring if the measured value exceeds the service limit.
Measure the piston pin outside diameter.

Fig 5: Measuring Piston Pin Diameter
Courtesy of GENERAL MOTORS CORP.
- Measure the piston pin outside diameter at several points.
- The production value is 34.495-34.50 mm (1.3581-1.3563 in) and the service limit is 34.450 mm (1.3563 in).
- Replace the piston pin if the measured value is less than the service limit.
Measure the piston pin to piston pin bore clearance.

Fig 6: Measuring The Piston Pin Bore
Courtesy of GENERAL MOTORS CORP.
- Measure the piston pin bore.
- Subtract the piston pin measurement that was taken previously from the piston pin bore measurement. The difference between these two measurements will be the piston pin to piston pin bore clearance.
- The production clearance is 0.004-0.017 mm (0.0002-0.0007 in) and the service limit is 0.017 mm (0.0007 in).
- If the piston pin to piston pin bore clearance is beyond specifications then replace the piston.
Measure the piston pin to connecting rod small end clearance.

Fig 7: Measuring Piston Pin To Connecting Rod Small End Clearance
Courtesy of GENERAL MOTORS CORP.
- Measure the inside diameter of the connecting rod small end.
- Subtract the piston pin measurement that was taken previously from the connecting rod small end measurement. The difference between these two measurements will be the piston pin to connecting rod clearance.
- The production clearance is 0.012-0.027 mm (0.0005-0.0011 in) and the service limit is 0.08 mm (0.0031 in).
- Replace the connecting rod if the piston pin to connecting rod small end clearance is beyond specifications. The connecting rod small end bushing is not serviceable.