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Engine Block Cleaning and Inspection

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    Fig 1: Cleaning Gasket Mating Surfaces
    GM412450Courtesy of GENERAL MOTORS CORP.
  1. Clean the sealing material from the gasket mating surfaces.
  2. Clean the engine block and lower crankcase in a cleaning tank with solvent appropriate for aluminum.
  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 Repair .
    8. Fig 2: Using Straight Edge & Feeler Gage To Check Deck Surface Flatness
    GM63337Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: Do not attempt to machine the lower crankcase to engine block surfaces.
  8. Use a straight edge and a feeler gage to check the deck surface for flatness. Carefully machine minor irregularities. Replace the block if more than 0.254 mm (0.010 in) must be removed.
  9. Inspect the oil pan rail for nicks. Inspect the front cover attaching area for nicks. Use a flat mill file to remove any nicks.
    10. Fig 3: Cleaning Sealing Material From Gasket Mating Surfaces - Engine Block Side
    GM412455Courtesy of GENERAL MOTORS CORP.
  10. Clean the sealing material from the gasket mating surfaces on the lower crankcase engine block side.
    11. Fig 4: Cleaning Sealing Material From Gasket Mating Surfaces - Oil Pan Side
    GM412458Courtesy of GENERAL MOTORS CORP.
  11. Clean the sealing material from the gasket mating surfaces on the lower crankcase oil pan side.
    12. Fig 5: Measuring Engine Block Flange Runout
    GM63324Courtesy of GENERAL MOTORS CORP.
  12. Inspect the mating surfaces of the transmission face.
    13. NOTE: A broken flywheel may result if the transmission case mating surface is not flat.
  13. Use the following procedure in order to measure the engine block flange runout at the mounting bolt hole bosses:
    1. Temporarily install the crankshaft. Measure the crankshaft flange runout.
    2. Hold the gage plate flat against the crankshaft flange.
    3. Place the dial indicator stem on the transmission mounting bolt hole boss. Set the indicator to 0.
    4. Record the readings obtained from all of the bolt hole bosses. The measurements should not vary more than 0.203 mm (0.008 in).
    5. Recheck the crankshaft flange runout if the readings vary more than 0.203 mm (0.008 in).
    14. Fig 6: Inspecting Crankshaft Main Bearing Bores
    GM38663Courtesy of GENERAL MOTORS CORP.
  14. Inspect the crankshaft main bearing bores. Use a bore gage to measure the bearing bore concentricity and alignment.
  15. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
    16. Fig 7: Inspecting Cylinder Bores Using J 8087
    GM38662Courtesy of GENERAL MOTORS CORP.
  16. Inspect the cylinder bores. Inspect for the following items:
    • Wear
    • Taper
    • Runout
    • Ridging
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