Crankshaft and Bearings Clean and Inspect

CRANKSHAFT MEASUREMENT





1. Clean the crankshaft bearings and the crankshaft journals with solvent and compressed air.
2. Inspect each bearing journal and bearing for damage.
3. Inspect the reluctor ring for any damage to the ring teeth.
4. Support the crankshaft on wooden v-blocks at the front (1) and rear (5) journals.
5. Check the crankpins for undersize using an outside micrometer.





6. Measure the main bearing and crankpin journals for out-of-round using the following procedure:
6.1. Using an outside micrometer, measure the journal at the extreme front and rear locations on the journal. Call these points A and B.
6.2. Measure the journal in two new locations exactly 90° from the first points. Call these points C and D.
6.3. Subtract A from C and B from D. The differences will indicate journal out-of-round.
6.4. The out-of-round should not exceed 0.004 mm (0.00016 inch) maximum.
6.5. If the specifications are exceeded, replace the crankshaft.
7. Measure the main bearing and crankpin journals for taper using the following procedure:
7.1. Using an outside micrometer, measure the journal at the extreme front (A) and rear (B) of the journal parallel to the crankshaft centerline.
7.2. Subtract the smallest from the largest measurement. The result will be the journal taper.
7.3. If the main bearing journal taper exceeds 0.004 mm (0.00016 inch), replace the crankshaft.
7.4. If the crankpin journal taper exceeds 0.005 mm (0.0002 inch), replace the crankshaft.
8. If the crankshaft journals are damaged or worn beyond dimensions, replace the crankshaft. No machining of the crankshaft journals is allowed.

CRANKSHAFT BEARING MEASUREMENT





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 bearing 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.