Crankshaft and Bearing Clean and Inspect
^ Tool(s) Required- J 7872 Magnetic Base Dial Indicator Set
Important: Use care when handling the crankshaft. Avoid damage to the bearing surfaces.
1. Clean the oil, sludge, and carbon from the crankshaft with solvent.
2. Thoroughly clean all oil passages and inspect for restrictions and burrs.
Caution: Wear safety glasses in order to avoid eye damage.
3. Dry the crankshaft with compressed air.
4. Inspect the keyway.
5. Perform a visual inspection of the crankshaft for damage.
Important: Replace the crankshaft if cracks, severe gouges or burned spots are found. Slight roughness may be removed with a fine polishing cloth soaked in clean engine oil. Burrs may be removed with a fine oil stone.
6. Inspect the crankshaft journals (1) for wear. The journals should be smooth with no signs of scoring, wear, or damage.
7. Inspect the crankshaft journals for grooves and scoring (2).
8. Inspect the crankshaft journals for roughness and scratches (3).
9. Inspect the crankshaft journals for pitting or imbedded bearing material (4). Inspect the corresponding bearing inserts for imbedded foreign material. If foreign material exists find the cause and repair it.
10. Inspect the crankshaft bearings for craters or pockets. Flattened sections on the bearing halves also indicate fatigue.
11. Inspect the crankshaft bearings for excessive scoring or discoloration (overheating).
12. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.
13. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the bearing. If the lower half of the bearing is worn or damaged, replace both upper and lower halves. Generally, if the lower half is suitable for use, the upper half should also be suitable for use.
14. Measure the crankshaft connecting rod and main bearing journals for out-of-round. Measure each journal in 2 places 90 degrees apart. The difference between these 2 measurements is the out-of-round of the journal.
Maximum Out-of-Round: 0.01 mm (0.0004 inch)
15. Measure the crankshaft journals for taper. Measure the journal at each end of the journal. The difference between these 2 measurements is the taper of the journal.
Maximum Taper: 0.01 mm (0.0004 inch)
16. Regrind or replace the crankshaft if the above measurements exceed specifications.
17. Note the location of the main bearing high spots. If they are not in line, the crankshaft is bent and must be replaced.
18. Measure the crankshaft runout. Support the crankshaft on the front and rear journals using wooden V blocks.
19. Measure the crankshaft runout at the center journal using the J 7872.
20. Replace the crankshaft if the measurements exceed specifications.
Maximum Runout: 0.06 mm (0.0023 inch)
21. Measure the flywheel (2) surface runout using the J 7872.
22. Replace or repair the flywheel if the runout exceeds specifications.
Maximum Runout: 0.2 mm (0.0078 inch)
Important: The lower crankcase must be installed and properly torqued in order to measure crankshaft end play.
23. Measure the crankshaft end play using the J 7872.
Standard Crankshaft End Play: 0.10-0.35 mm (0.0039-0.0138 inch)
Maximum Crankshaft End Play: 0.42 mm (0.0165 inch)
24. The crankshaft thrust bearing is available in standard and oversized.
Standard Thrust Bearing Thickness: 2.500 mm (0.984 inch)
0.125 mm (0.0049 inch) Oversize Thrust Bearing Thickness: 2.563 mm (0.1009 inch)
25. If the end play exceeds the maximum replace the thrust bearing with a new standard size thrust bearing. If the end play still exceeds the maximum replace the thrust bearing with a new oversize thrust bearing.