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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 684 (ENGINE MECHANICAL - 3.8L)REPAIR INSTRUCTIONSOFF-VEHICLE REPAIR INSTRUCTIONSENGINE BLOCK CLEANING AND INSPECTIONTOOLS REQUIRED
1999 GMC Forward Control 5.7 R, Automatic

Tools Required

1999 GMC Forward Control 5.7 R, AutomaticSECTION Tools Required
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
  • J 8087  Cylinder Bore Gage
  • J 8001  Dial Indicator Set
  1. Clean the sealing material from the gasket mating surfaces.
  2. Boil the engine block in caustic solution.
  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 holes with a tap. If necessary, drill out the holes and install thread inserts. Refer to THREAD REPAIR  .
  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.
    Fig 1: Cleaning Sealing Material From Gasket Mating Surfaces
    G02083807Courtesy of GENERAL MOTORS CORP.
  10. Inspect the mating surfaces of the transmission case.
    NOTE: A broken flywheel may result if the transmission case mating surface is not flat.
  11. Use the following procedure to measure the engine block flange runout at the six mounting bolt hole bosses:
    1. 11.1. Temporarily install the crankshaft. Measure the crankshaft flange runout.
    2. 11.2. Hold the gauge plate flat against the crankshaft flange.
    3. 11.3. Place J 8001  on the transmission mounting bolt hole boss. Set the indicator to 0.
    4. 11.4. Record the readings obtained from all of the bolt hole bosses. The measurements should not vary more than 0.254 mm (0.010 in).
    5. 11.5. Recheck the crankshaft flange runout if the readings vary more than 0.254 mm (0.010 in).
    Fig 2: Measuring Engine Block Flange Runout
    G02083808Courtesy of GENERAL MOTORS CORP.
  12. Inspect the crankshaft main bearing bores. Use J 8087  to measure the bearing bore concentricity and alignment at the following locations:
    • The camshaft
    • The crankshaft

    Important:  Recondition the engine block with the crankshaft main bearing caps and the crankshaft main bearing cap side bolts installed and tightened to specification.

  13. Ensure that the crankshaft main bearing caps are installed correctly. The arrows should point toward the front of the engine.
  14. Replace the engine block if the bores are out of specification.
    Fig 3: Measuring Bearing Bore Concentricity
    G02083809Courtesy of GENERAL MOTORS CORP.
  15. Use J 8087  to inspect the cylinder bores. Inspect for the following items:
    • Wear
    • Taper
    • Run-out
    • Ridging

    Important:  If the bore is worn beyond the limits, refit the bore with oversized pistons. Select the smallest available oversize piston. Refer to CYLINDER BORING AND HONING  .

  16. Leave sufficient material to allow honing when fitting the piston.
    Fig 4: Inspecting Cylinder Bores
    G02083810Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.