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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 428 (Engine Mechanical - 8.1L V8) >> Overhaul >> Crankshaft Bearing Cleaning & Inspection >> Measuring Crankshaft Bearing Clearance Using Plastigage®

Measuring Crankshaft Bearing Clearance Using Plastigage®

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  1. Install the crankshaft and the new crankshaft bearings into the block, making sure not to damage the reluctor rings of the crankshaft.
  2. Install gaging plastic the full width of the crankshaft journal.
  3. Install crankshaft bearing caps and the crankshaft bearing cap bolts and studs. Tighten the crankshaft bearing cap inner bolts to specification. See TORQUE SPECIFICATIONS . Tighten the crankshaft bearing cap outer studs to specification. Using a Torque Angle Meter, tighten the crankshaft bearing cap inner bolts an additional 90 degrees. Using torque angle meter, tighten the crankshaft bearing cap outer studs an additional 80 degrees.
  4. Remove crankshaft bearing cap bolts and the crankshaft bearing caps. The gaging plastic may adhere to either the crankshaft journal or the crankshaft bearing surfaces.
  5. On the edge of the gaging plastic envelope there is a graduated scale. Without removing the gaging plastic, measure the compressed width at the widest point.
  6. If the flattened gaging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crankshaft journal. Normally the crankshaft journals wear evenly and are not out-of-round. However, if a crankshaft bearing is being fitted to an out-of-round crankshaft journal, see CRANKSHAFT  table, be sure to fit to the maximum diameter of the crankshaft journal. If the crankshaft bearing is fitted to the minimum diameter and the crankshaft journal is excessively out-of-round, the interference between the crankshaft bearing and the crankshaft journal will result in rapid crankshaft bearing failure.
  7. Compare the crankshaft bearing clearance to the specifications. See CRANKSHAFT  table.
  8. If crankshaft bearing clearances exceeds specifications, replace components as required.
  9. Measure new crankshaft bearing inside diameter using the same method.
  10. Replace crankshaft if the proper clearances cannot be obtained with standard size bearings.
  11. Remove flattened gaging plastic.
  12. Measure remaining crankshaft journals.
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