GM Service Manual Online
For 1990-2009 cars only

Special Tools

EN-8087 Cylinder Gauge

For equivalent regional tools, refer to Special Tools.


    Object Number: 2026861  Size: SH
  1. Clean the sealing material from the gasket mating surfaces (2).
  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. Object Number: 2026862  Size: SH

    Note: Do not attempt to machine the lower crankcase to engine block surfaces.


    Object Number: 2026863  Size: SH
  9. Engine block for sag in length and width on the sealing surfaces and for distortion along the diagonals.
  10. If the deck surface is out of specification, replace the block. Do not machine the block.


    Object Number: 2026763  Size: SH
  11. Clean the sealing material from the gasket mating surfaces on the lower crankcase oil pan side.

  12. Object Number: 2026766  Size: SH
  13. Inspect the crankshaft main bearing bores. Use the EN-8087 gauge  (1) to measure the bearing bore concentricity and alignment.
  14. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.

  15. Object Number: 2026767  Size: SH
  16. Inspect the cylinder bores using the EN-8087 gauge  (1). Inspect for the following items:
  17. • Wear
    • Taper
    • Runout
    • Ridging
  18. Refer to Engine Mechanical Specifications.
  19. If the cylinder bores are out of specification, replace the engine block.