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Home >> Cadillac >> 2004 >> CTS Base, 3.2 N >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 15 (Engine Mechanical - 3.6L (Ly7) (Repair Procedures -- 3 Of 5)) >> Off-Vehicle Repair Instructions - Part 2 >> Piston, Connecting Rod, and Bearings Cleaning and Inspection >> Piston Ring Measurement Procedure

Piston Ring Measurement Procedure

WARNING: This page is about a different variant/trim than selected.
    Fig 1: Measuring Piston Ring End Gap
    GM4968Courtesy of GENERAL MOTORS CORP.
  1. Measure the piston ring end gap using the following procedure:
    1. Place the piston ring 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 gages. Refer to Engine Mechanical Specifications .
    3. If the clearance exceeds the provided specifications, the piston rings must be replaced.
    4. Repeat the procedure for all the piston rings.
    2. Fig 2: Measuring Piston Ring Side Clearance
    GM576560Courtesy of GENERAL MOTORS CORP.
  2. Measure the piston ring side clearance using the following procedure:
    1. Roll the piston ring 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, use feeler gages to check clearance at multiple locations.
    3. Compare the measurements with piston ring side clearance listed in the Engine Mechanical Specifications .
    4. If the clearance is greater than specifications, replace the piston rings.
    3. Fig 3: View Of Lower Compression Piston Ring Mark
    GM562823Courtesy of GENERAL MOTORS CORP.
  3. There is a locating dimple (1) on the compression rings near the end for identification. Install the compression rings with the dimple facing up.
  4. If the new ring does not reduce the clearance to the proper specification, install a new piston.
  5. If the new piston does not meet clearance specifications, the cylinder block may need to be oversized to 0.25 mm (0.010 in). There is only one size of oversized pistons and rings available for service.
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