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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 11 (ENGINE MECHANICAL - 4.3L UNIT REPAIR)REPAIR INSTRUCTIONSPISTON, CONNECTING ROD & BEARING INSTALLATIONPISTON SELECTION
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Piston Selection

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Piston Selection
WARNING: This page is about a different variant/trim than selected.

Important:  Measurements of all components should be taken with the components at normal room temperature.

For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.

A used piston and piston pin set may be reinstalled if, after cleaning and inspection, the piston and piston pin are within specifications.

  1. Use the J 8087  in order to measure the cylinder bore diameter. Measure at a point 64 mm (2.5 in) from the top of the cylinder bore and 90 degrees to the crankshaft centerline.
    Fig 1: Measuring Cylinder Bore Diameter
    G02503045Courtesy of GENERAL MOTORS CORP.
  2. Measure the J 8087 with a micrometer and record the reading.
    Fig 2: Measuring Cylinder Bore Gage
    G02503046Courtesy of GENERAL MOTORS CORP.
  3. With a micrometer or caliper at a right angle to the piston pin bore, measure the piston 11 mm (0.433 in) from the bottom of the skirt.
    4. Fig 3: Measuring Piston Diameter
    G02503047Courtesy of GENERAL MOTORS CORP.
  4. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance. Refer to Engine Mechanical Specifications .
  5. If the proper clearance cannot be obtained, then select another piston and measure the clearances. If the proper fit cannot be obtained, the cylinder bore may require honing or boring.
  6. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation into the proper cylinder.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.