Piston, Pin, and Piston Rings

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Locating Cast Dimples

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NOTE: 2010 Model Year: RPO's L9H and L94 have 1st and 2nd design piston and ring assemblies. If piston and/or ring assemblies are being replaced, design level must be identified for proper replacement.

1st design pistons have a cast dimple (1) on top of the piston 14.5 mm (a) inboard from outside edge.
2nd design pistons have a cast dimple (2) on top of the piston 5.5 mm (b) inboard from outside edge.

Fig 2: View Of Piston, Pin & Piston Rings

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NOTE:

Replace pistons, pins, and connecting rods that are damaged or show signs of excessive wear.
The piston and pin are to be serviced as an assembly.
Do not wire brush any part of the piston.
Measurement of the components should be taken with the components at normal room temperature.

Clean the varnish and carbon from the piston (107) using cleaning solvent.

WARNING: Refer to Safety Glasses Warning .

Dry the components with compressed air.

Fig 3: Cleaning Piston Ring Grooves

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Clean the piston ring grooves with a suitable ring groove cleaning tool.
Clean the oil lubrication holes and slots.

Fig 4: Identifying Piston Damage Inspection Areas

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Inspect the piston for the following conditions:
- Cracks in the piston ring lands, the piston skirt, or pin bosses
- Piston ring grooves for nicks, burrs, or warpage which may cause the piston ring to bind
  MINOR imperfections may be removed from the piston with a fine file.
- Eroded areas at the top of the piston (1)
- Scuffed or damaged skirts (2)
- Scoring to the piston pin bore (3) or piston pin

Fig 5: Inserting Piston Ring Into Ring Groove

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Insert the edge of the piston ring into the piston ring groove.
Roll the piston ring completely around the piston. If binding is caused by a distorted ring groove, MINOR imperfections may be removed with a fine file. If binding is caused by a distorted piston ring, replace the rings, as required.

Fig 6: Measuring Piston Ring Side Clearance

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Measure the piston ring side clearance with a feeler gauge. If side clearance is not within specifications, try another piston ring. If the proper ring-to-groove clearance cannot be obtained, replace the piston and pin as an assembly. Refer to Engine Mechanical Specifications (RPO L20 VIN A) or Engine Mechanical Specifications (RPO L96 VIN G) or Engine Mechanical Specifications (RPO L9H) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY6 VIN K) .

Fig 7: Measuring Piston Pin Diameter

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To determine piston pin-to-bore clearance, use a micrometer and measure the piston pin outside diameter (OD).

Fig 8: Measuring Piston Pin-To-Bore Clearance

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To determine the piston pin-to-bore clearance, use an inside micrometer and measure the piston pin bore inside diameter (ID).
Subtract the piston pin OD measurement from the piston pin bore ID measurement to determine pin-to-bore clearance. Refer to Engine Mechanical Specifications (RPO L20 VIN A) or Engine Mechanical Specifications (RPO L96 VIN G) or Engine Mechanical Specifications (RPO L9H) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY6 VIN K) .