Piston Ring Measurement Procedure

Courtesy of GENERAL MOTORS COMPANY

Measure the piston ring end gap using the following procedure:

1. Place the piston ring (1) in the area of the bore where the piston ring will travel approximately 25 mm (1 in) down from the deck surface. Ensure that the ring is square with the cylinder bore by positioning the ring with the piston head.
2. Measure the end gap of the piston ring with feeler gauges (2). Engine Mechanical Specifications (L84) , or Engine Mechanical Specifications (L87)
3. If the clearance exceeds the provided specifications, the piston rings must be replaced.
4. Repeat the procedure for all the piston rings.

Courtesy of GENERAL MOTORS COMPANY

Measure the piston ring side clearance using the following procedure:

1. Roll the piston ring (1) entirely around the piston ring groove. If any binding is caused by the ring groove, dress the groove with a fine file. If any binding is caused by a distorted piston ring, replace the ring.
2. With the piston ring on the piston (2), use feeler gauges to check clearance at multiple locations.
3. Compare the measurements with piston ring side clearance listed in the Engine Mechanical Specifications (L84) , or Engine Mechanical Specifications (L87) .
4. If the clearance is greater than specifications, replace the piston rings.