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Home >> GMC >> 2021 >> Yukon XL AT4 >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine Mechanical - 5.3L (L84) Or 6.2L (L87) - Repair Instructions ( 2 Of 12) >> Repair Instructions >> Engine Block Overhaul >> Engine Block Deck Flatness Inspection

Engine Block Deck Flatness Inspection

  1. GM5366232Courtesy of GENERAL MOTORS COMPANY

    Ensure the engine block decks are clean and free of gasket material.

  2. Inspect the surface for any imperfections or scratches that could inhibit proper cylinder head gasket sealing.
  3. Place a straight-edge (1) diagonally across the engine block deck face surface.
  4. Measure the clearance between the straight-edge (1) and the engine block deck face using a feeler gauge (2) at 4 points along the straight-edge.
  5. If the warpage is less than 0.10 mm (0.004 in), the engine block deck surface does not require resurfacing.
  6. If the warpage is between 0.10 - 0.20 mm (0.004 - 0.008 in) or any imperfections or scratches that could inhibit proper cylinder head gasket sealing are present, the engine block deck surface requires resurfacing.
  7. If resurfacing is required the maximum amount that can be removed is 0.25 mm (0.010 in).
  8. If the engine block deck surface requires more than 0.25 mm (0.010 in) material removal the block must be replaced.