Bearing Inspection

1. Inspect the main bearings for fatigue indicated by craters or pockets. Flattened sections on the bearing halves also indicate fatigue.





2. Inspect the main bearings for excessive scoring or discoloration on both front and back of the bearing halves.
3. Inspect the main bearings for dirt imbedded into the bedding material.





4. Inspect the main bearings for improper seating indicated by bright, polished sections.
5. If any of the above conditions exist, replace the crankshaft bearings.
6. Wipe any oil from the crankshaft journals and the bearing inserts.
7. Install the upper and the lower crankshaft bearings.
8. Place a length of fresh, room temperature plastic gaging material all the way across all the main bearing journals.
9. Reinstall the lower crankcase and the oil scraper.
10. After reaching final torque, allow the assembly to sit for two minutes.
11. Remove the main bearing bolts.
12. Remove the lower crankcase.





13. Determine the main bearing clearance by comparing the width of the flattened plastic gaging material at its widest point with the graduation on the gaging material container.
14. If the bearing clearance is greater than 0.0635 mm (0.0025 inch), replace the main bearings.
15. If the new bearings do not reduce the clearance to 0.015-0.055 mm (0.0006-0.002 inch) a new crankshaft will be required. Undersized bearings are not available and no crankshaft grinding is allowed.
16. If reusing the crankshaft, clean the plastic gaging material from the bearing journals.