Main Bearings
- With oil pan removed, support crankshaft at both ends. Start with rear main cap and work forward. Remove one cap at a time and use Plastigage method to check clearances. Replace bearings not within specifications.
- When checking No. 1 bearing, loosen accessory drive belts to prevent tapered reading from Plastigage. New bearings are available in standard 0.001" (0.025 mm) and 0.002" (0.050 mm) for new and used crankshafts, and in 0.010" (0.25 mm) and 0.020" (0.50 mm) for reconditioned crankshafts.NOTE: Some journals on some crankshafts (not necessarily all journals) may be factory-ground to 0.010" (0.250 mm) undersize.
- Check crankshaft journal for wear. If journal is not within specifications, remove crankshaft and grind to 0.010" (0.250 mm) undersize.NOTE: A standard bearing half may be used with a 0.001" (0.025 mm) undersize or a 0.001" (0.025 mm) undersize bearing may be used with a 0.002" (0.050 mm) to obtain correct clearance.
- Using a suitable tool, installed in crankshaft oil hole, rotate crankshaft clockwise to remove upper bearing half. Coat new upper bearing half with engine oil, press firmly to crankshaft journal and rotate bearing into place by turning crankshaft in counterclockwise direction.
- Oil new lower bearing and install in bearing cap. Install main bearing cap with arrows pointing toward front of engine. Tighten all bearing caps except rear main, to specifications. Tighten rear main cap to 10-12 ft.lbs., then tap crankshaft rearward, then forward with lead hammer. Retorque all caps to specifications.