GM 94853352 Engine Crankshaft

Examine the crankpin and main journal surfaces for scoring, scratches, or corrosion; if any are evident, the crankshaft will need professional regrinding. Use a micrometer to test each journal and crankpin at several points for ovality; if it exceeds 0.001 inch, regrinding is necessary. Undersize bearings are available to match the recommended regrind diameter, and typically, the parts salesperson will provide the correct bearings with the reconditioned crankshaft. After high mileage, main and connecting rod bearings may wear, leading to excessive running clearance, which can be checked using a proprietary product like 'Plastigage' after refitting the original bearings and caps and tightening the cap bolts to the specified torque settings. Always install new shell bearings after verifying the crankshaft journals and crankpins for ovality and confirming their diameters are standard or regrind sizes, and avoid turning the crankshaft while the 'Plastigage' is in place. Checking the connecting rod bearings follows a similar process, with the correct running clearance also specified. To check crankshaft endplay, force the crankshaft to the extreme front position and use a feeler gauge at the front end of the rear main bearing, ensuring the permissible clearance is adhered to.

Fit in the rear main bearing oil seal in the cylinder block and rear main bearing cap grooves; it will have the seal lips directed to the forwards end of the engine while the dust seal will face outwards towards the rear end. If the seal has two lips then to the helix lip should also be facing forward. Wipe the seal lips with clean rags or if available with engine oil. Subsequently, fit the main bearings into the cylinder block and the caps of the main bearings with the help of the engine oil for lubrication of the bearing surfaces. With much attention, fix the crankshaft suitably to avoid imparting damages to the bearings surfaces but the crankshaft journals should be smeared with the engine oil. Squash on a very thin layer of RTV sealant onto the mating surface of the rear main bearing cap and at the ends of the seal and other nearby regions on the block, without coming into contact with the crankshaft or the seal. Place the main bearing caps as they fit into position and these should have the arrow like towards the front side of the engine. Torque tighten the main bearing caps except the rear cap bolts which should be tightened at 12ft/lbs. Strike gently the end of the crankshaft rearwards and forwards on the block with a hammer and wood so that the two rear main bearing thrust faces get in alignment, and then tighten the bearing cap again to the desirable torque.

If the upper half shell bearings are to be removed for reuse, keep them identified and separate from their corresponding lower half shell bearings.