GM Service Manual Online
For 1990-2009 cars only

Engine Block Cleaning and Inspection Upper

Cleaning Procedure

  1. Remove any old thread sealant and gasket material or sealant.
  2. Clean all the following areas with solvent:
  3. • Sealing surfaces
    • Cooling passages
    • Oil passages
    • Bearing journals
  4. Clean all threaded and through holes with solvent.
  5. Caution: Wear safety glasses in order to avoid eye damage.

  6. Dry the upper engine block with compressed air.

Visual Inspection

  1. Inspect the crankshaft bearing journals for damage or spun bearings. The crankshaft bearing journals are not repairable, if the crankshaft bearing journals are damaged the cylinder block assembly must be replaced.
  2. Inspect the crankshaft rear oil seal bore for damage. The crankshaft rear oil seal bore is not repairable, if the crankshaft rear oil seal bore is damaged the cylinder block assembly must be replaced.
  3. Inspect all sealing and mating surfaces for damage, repair or replace the cylinder block assembly if necessary.
  4. Inspect all threaded and through holes for damage or excessive debris.
  5. Inspect all bolts for damage, if damaged replace with new bolts only.
  6. Ensure the balance shaft bearings are not damaged. The balance shaft bearings are not serviced separately, if the balance shaft bearings are damaged the cylinder block assembly must be replaced.
  7. Inspect the cylinder walls for cracks or damage. The cylinders sleeves are not serviced separately, if the cylinders are damaged the cylinder block assembly must be replaced.
  8. Inspect the upper engine block for cracks. Do not repair any cracks. If cracks are found, the cylinder block assembly must be replaced.
  9. Repair any damaged threaded holes. Refer to Thread Repair Specifications and Thread Repair .

Measuring Cylinder Bore Diameter


    Object Number: 287937  Size: SH
  1. Measure the cylinder bore diameter 37 mm (1.47 in) from the deck face using a cylinder bore micrometer.
  2. Compare your results with the Engine Mechanical Specifications . If the cylinder diameter exceeds the specifications, the cylinder block must be replaced. There are no oversized pistons and rings available for service.

Measuring Cylinder Bore Taper

  1. Measure the cylinder bore along the thrust surfaces (perpendicular to the crankshaft centerline) at 5 mm (0.20 in) below the deck surface and record your measurement.
  2. Measure the cylinder bore along the thrust surfaces (perpendicular to the crankshaft centerline) at 102 mm (4.00 in) below the deck surface and record your measurement.
  3. Calculate the difference between the two measurements. The result will be the cylinder taper.
  4. Compare your results with the Engine Mechanical Specifications . If the cylinders exceed the specifications, replace the cylinder block. There are no oversized pistons and rings available for service.

Measuring Cylinder Bore Out-of-Round

  1. Measure both the thrust and non-thrust cylinder diameter 5 mm (0.20 in) below the deck. Record your measurements.
  2. Calculate the difference between the two measurements. The result will indicate out-of-round at the upper end of the cylinder.
  3. Measure both the thrust and non-thrust cylinder diameter at 102 mm (4.00 in) below the deck surface. Record your measurements.
  4. Calculate the difference between the two measurements. The result will indicate out-of-round at the lower end of the cylinder.
  5. Compare your results with the Engine Mechanical Specifications . If the cylinders exceed these specifications, replace the cylinder block. There are no oversized pistons and rings available for service.

Engine Block Cleaning and Inspection Lower

Cleaning Procedure

  1. Remove any old thread sealant and gasket material or sealant.
  2. Clean all the following areas with solvent:
  3. • Sealing surfaces
    • Oil passages
    • Bearing journals
  4. Clean all threaded and through holes with solvent.
  5. Caution: Wear safety glasses in order to avoid eye damage.

  6. Dry the lower engine block with compressed air.

Visual Inspection

  1. Inspect the crankshaft bearing journals for damage or spun bearings. The crankshaft bearing journals are not repairable, if the crankshaft bearing journals are damaged the cylinder block assembly must be replaced.
  2. Inspect the crankshaft rear oil seal bore for damage. The crankshaft rear oil seal bore is not repairable, if the crankshaft rear oil seal bore is damaged the cylinder block assembly must be replaced.
  3. Inspect all sealing and mating surfaces for damage, repair or replace the cylinder block assembly if necessary.
  4. Inspect all threaded and through holes for damage or excessive debris.
  5. Inspect all bolts for damage, if damaged replace with new bolts only.
  6. Ensure the oil bypass valve is not damaged. The oil bypass valve is not serviced separately, if the oil bypass valve is damaged or not operating properly the cylinder block assembly must be replaced.
  7. Inspect the crankshaft oil scraper for cracks or damage, replace if cracked or damaged.
  8. Inspect the lower engine block for cracks. Do not repair any cracks. If cracks are found, the cylinder block assembly must be replaced.
  9. Repair any damaged threaded holes. Refer to Thread Repair Specifications and Thread Repair .