Piston, Connecting Rod, and Bearings Cleaning and Inspection

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Refer to CLEANING SOLVENT CAUTION in Cautions and Notices.

Clean the piston and connecting rod in solvent.
CAUTION: Refer to SAFETY GLASSES CAUTION in Cautions and Notices.
Dry the components with compressed air.
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.

Fig 1: Cleaning Piston Ring Grooves
Courtesy of GENERAL MOTORS CORP.
Clean the piston ring grooves with a suitable ring groove cleaning tool.
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.
Clean the piston oil lubrication holes and slots.
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.
Inspect the piston for scoring, wear or other damage.

Fig 2: Inspecting Piston For Scoring, Wear Or Other Damage
Courtesy of GENERAL MOTORS CORP.
To determine the piston-to bore clearance, use a micrometer and measure the piston pin.

Fig 3: Measuring Piston Pin With Micrometer
Courtesy of GENERAL MOTORS CORP.
To determine the piston pin-to bore clearance, use an inside micrometer and measure the piston pin bore.
To determine the piston pin-to-bore clearance, subtract the piston pin diameter from the piston pin bore diameter.

Fig 4: Locating Piston Pin-To Bore Clearance
Courtesy of GENERAL MOTORS CORP.
Inspect the connecting rod for an out-of-round bearing bore.

Fig 5: Inspecting Connecting Rod Out-Of-Round Bearing Bore
Courtesy of GENERAL MOTORS CORP.
Inspect the connecting rod for twisting.

Fig 6: Inspecting Connecting Rod For Twisting
Courtesy of GENERAL MOTORS CORP.
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.

Fig 7: Inspecting Connecting Rod Cap Bolts
Courtesy of GENERAL MOTORS CORP.