Engine Block Cleaning and Inspection

Special Tools 

EN-8087  Cylinder Gauge

For equivalent regional tools, refer to Special Tools .

1. Clean the sealing material from the gasket mating surfaces (2).
   Fig 1: Engine Block

   Courtesy of GENERAL MOTORS COMPANY
2. Clean the engine block (1) and lower crankcase in a cleaning tank with solvent appropriate for aluminum. Refer to Adhesives, Fluids, Lubricants and Sealers  for the recommended solvent.
3. Flush the engine block with clean water or steam.
4. Clean the oil passages.
5. Clean the blind holes.
6. Spray the cylinder bores and the machined surfaces with engine oil.
7. Inspect the threaded holes. Clean the threaded holes with a rifle brush. If necessary, drill out the holes and install thread inserts. Refer to Thread Inserts .
8. Inspect the engine block for sag in length and width on the sealing surfaces.
   Fig 2: Inspecting Engine Block For Sag In Length And Width On Sealing Surfaces

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: Do not attempt to machine the lower crankcase to engine block surfaces.
9. Inspect the engine block for distortion along the diagonals.
   Fig 3: Inspecting Engine Block For Distortion Along Diagonals

   Courtesy of GENERAL MOTORS COMPANY

   If the deck surface is out of specification, replace the block. Do not machine the block.

10. Clean the sealing material from the gasket mating surfaces (1) on the lower crankcase oil pan side.
    Fig 4: Gasket Mating Surfaces

    Courtesy of GENERAL MOTORS COMPANY
11. Inspect the crankshaft main bearing bores. Use the EN-8087  gauge (1) to measure the bearing bore concentricity and alignment.
    Fig 5: Measuring Bearing Bore Concentricity And Alignment Using Gauge Tool

    Courtesy of GENERAL MOTORS COMPANY
12. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
13. Inspect the cylinder bores using the EN-8087  gauge (1). Inspect for the following items:
    Fig 6: Inspecting Cylinder Bore

    Courtesy of GENERAL MOTORS COMPANY
    • Wear
    • Taper
    • Runout
    • Ridging
14. Check the cylinder bores specifications. Refer to Engine Mechanical Specifications .
15. If the cylinder bores are out of specification, replace the engine block.