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Home >> Pontiac >> 2008 >> Grand Prix GXP >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Engine Mechanical - 3.8L) >> Repair Instructions - Off Vehicle >> Piston, Connecting Rod, and Bearing Cleaning and Inspection

Piston, Connecting Rod, and Bearing Cleaning and Inspection

WARNING: This page is about a different variant/trim than selected.
CAUTION: Refer to CLEANING SOLVENT CAUTION .
    Fig 1: View Of Piston Pin, Piston, Clips & Connecting Rod
    GM35866Courtesy of GENERAL MOTORS CORP.
  1. Clean the piston and connecting rod in solvent.
  2. CAUTION: Refer to SAFETY GLASSES CAUTION .
  3. Dry the components with compressed air.
  4. NOTE: The piston ring groove must only be cleaned with a ring groove cleaning tool. Proper engine performance and durability depends on the straightness and smoothness of the ring groove. Cleaning the piston ring groove with an improper tool can damage the piston ring groove and effect the performance and durability of the engine.
  5. Clean the piston ring grooves with a suitable ring groove cleaning tool.
  6. NOTE: The oil lubrication holes/slots must be cleaned with a suitable tool. Proper engine performance and durability depends on the cleanliness and smoothness of the holes/slots. Cleaning the oil lubrication holes/slots with an improper tool may damage the oil lubrication holes/slots and effect the performance and durability of the engine.
  7. Clean the piston oil lubrication holes and slots.
  8. Fig 2: Identifying Piston Damage Inspection Areas
    GM156168Courtesy of GENERAL MOTORS CORP.
  9. Inspect the piston for the following conditions:
    • Eroded areas (1) on top of the piston
    • Scuffed or damaged skirt (2)
    • Damage to the pin bore (3)
    • Cracks in the piston ring lands, the piston skirt, or the pin bosses
    • Piston ring grooves for nicks, burrs, or other warpage which may cause the piston ring to bind.
  10. Inspect the piston for scoring, wear or other damage.
  11. Fig 3: Measuring Piston Pin Diameter
    GM4976Courtesy of GENERAL MOTORS CORP.
  12. To determine the piston-to bore clearance, use a micrometer and measure the piston pin.
  13. Fig 4: Using Inside Micrometer & Measuring Piston Pin Bore
    GM1229783Courtesy of GENERAL MOTORS CORP.
  14. To determine the piston pin-to bore clearance, use an inside micrometer and measure the piston pin bore.
  15. To determine the piston pin-to-bore clearance, subtract the piston pin diameter from the piston pin bore diameter.
  16. Fig 5: View Of Connecting Rod
    GM156167Courtesy of GENERAL MOTORS CORP.
  17. Inspect the connecting rod for an out-of-round bearing bore.
  18. Fig 6: Identifying Twisted Connecting Rod
    GM156169Courtesy of GENERAL MOTORS CORP.
  19. Inspect the connecting rod for twisting.
  20. Fig 7: Inspecting Connecting Rod Cap Bolts
    GM187037Courtesy of GENERAL MOTORS CORP.
  21. Inspect the connecting rod cap bolts for stretch (compare to known good bolt) (1) is a stretched bolt, (2) is a new or good bolt.