Cylinder Bore And Crankshaft Bearing Bore

Install the crankshaft bearing cap tie plate and tighten.
NOTE: Old bolts can be used for the measuring procedure.
Inspect the crankshaft main bearing bores. Use the EN-8087 gauge (1) to measure the bearing bore roundness tolerance. Refer to Engine Mechanical Specifications to find the permitted values.

Fig 1: Measuring Bearing Bore Concentricity And Alignment Using Gauge Tool
Courtesy of GENERAL MOTORS COMPANY
Replace the engine block and crankshaft bearing cap tie plate if the crankshaft bearing bores are out of specification.
Inspect the cylinder bores using the EN-8087 gauge (1). Inspect for the following items:

Fig 2: Inspecting Cylinder Bore
Courtesy of GENERAL MOTORS COMPANY
- Wear
- Taper
- Runout
- Ridging
Refer to Engine Mechanical Specifications to find the permitted values.
If the cylinder bores are out of specification, replace the engine block.
Remove the crankshaft bearing cap tie plate.