GM 12578164 Crankshaft Assembly

The crankshaft can only be removed when the engine is completely detached from the car; provided that the driveplate, crankshaft pulley, timing chain, oil pan, oil pump body, oil filter, and piston/connecting rod assemblies have been also removed. Before removal, but after loosening, check the crankshaft endplay using a dial indicator, zero it when you pry it to the rear then check it again when prying to the front from the rear; it should have average crankshaft endplay of between 0.003-0.010 inch. Sometimes it may not be possible to use the dial indicator; in this case, it is possible to use feeler gauges. For four cylinder models, turn both the lower crankcase and perimeter bolts gradually to a point that they can easily be unscrewed; then replace the lower crankcase bolts with new once while tightening them. Take off the lower crankcase after that, but be very careful not to lose the bearing inserts. Remove these then and for 3.4L engines lightening the main bearing cap bolts in the same manner for the 3.0L and 3.6L V6 models, remove the side bearing cap bolts. Remove the crankshaft from the engine using hoist and make sure the bearing caps of main bearings put back in position with the bearing insert in place. At installation, the engine block and crankshaft must be adsorbed; main bearing oil clearance check with Plastigage, and the width of the crushed ones relative to the scale. When clearance is not as specified, check on cleanliness and if necessary, get rid of bearing insert. On the removal of all the Plastigage residues, lubricate bearing surfaces with thin layer of grease or engine assembly for sub sequent laying of crankshaft back into place. Replace new main bearing cap bolts and tighten the bolts successively in accordance with the torque specifications and the crankshaft end play should also be checked. Then, turn the crankshaft to see if it binds; it should rotate freely with a running torque no more than 50 in-chosen units and replace the rear main oil seal.

The crankshaft as we have earlier seen can only be removed if the engine has been pulled out of the car which means DISASSEMBLED or REMOVED of the driveplate, crankshaft pulley, timing chain, oil pan, oil pump body, oil filter, piston/connecting rod assemblies. The rear main oil seal retainer must be removed by the dismantling of its bolts and then the crankshaft cannot be removed without the removal of this retainer. First tape a dial indicator on the crankshaft and use it to measure the endplay. Loosen the nut on the front of the crankshaft and turn it to bring the dial indicator to zero, then push again; the standard figure should fall in the region of between 0.003 to 0.010 inch. In case the dial indicator is missing, or unavailable, the clearance might be checked with feeler gauges. For a V6, turn the main bearing cap bolts up to but not beyond the point so that they can be undone by hand; for a four-cylinder engine, slacken the lower crankcase bolts in the sequence by which they were tightened. Take off the main bearing caps or lower crankcase as gently as possible so as not to lose the bearing inserts. Remove the crankshaft as it should be done with a help of an assistant and fit back the main bearing cap or lower crankcase half onto the engine block tightening the fasteners only lightly but making sure that the caps are placed in the correct manner. While installing considerfulness of the engine block and the crankshaft and even their wash. Set the we engine block on its bottom, if any initial bearing inserts are there have to be removed and then clean all bearing areas. Place a new upper main bearing insert into each of the main bearing saddles, the oil holes of which must correspond to those of the other component; put in the main lower bearing inserts to the related caps. Clean the faces of crankshaft and bearing insert, then position the crankshaft in the bear. The Plastigage is used to check the oil clearance of the main bearing, while the caps should be properly fitted without interfering with the content observed. Once the bolts have been tightened, the caps are next to be removed, so that the width of the Plastigage can be compared to the scale in order to check the clearance. If clearance is wrong check cleanliness and if necessary consider other bearing inserts. All traces of Plastigage should be cleaned off carefully. Before the bearings are finally installed, the faces of the bearing inserts should be wiped clean with a clean rag; a thin layer of grease or assembly lube should then be applied; this is when the crankshaft should be placed back in its usual position. Dry and clean the bearing insert faces and lubricate lightly while making sure there is no oil between the two then mating surfaces. All the bolts are to be installed and tightened and if they are lost, they have to be procured and used The crankshaft end play has to be checked again. This has to be done in order to check for binding of the crankshaft thus if it turns freely. Last, there is the rear main oil seal that should be put in its new one.

The crankshaft can only be removed when the engine is completely detached from the car; provided that the driveplate, crankshaft pulley, timing chain, oil pan, oil pump body, oil filter, and piston/connecting rod assemblies have been also removed. Before removal, but after loosening, check the crankshaft endplay using a dial indicator, zero it when you pry it to the rear then check it again when prying to the front from the rear; it should have average crankshaft endplay of between 0.003-0.010 inch. Sometimes it may not be possible to use the dial indicator; in this case, it is possible to use feeler gauges. For four cylinder models, turn both the lower crankcase and perimeter bolts gradually to a point that they can easily be unscrewed; then replace the lower crankcase bolts with new once while tightening them. Take off the lower crankcase after that, but be very careful not to lose the bearing inserts. Remove these then and for 3.4L engines lightening the main bearing cap bolts in the same manner for the 3.0L and 3.6L V6 models, remove the side bearing cap bolts. Remove the crankshaft from the engine using hoist and make sure the bearing caps of main bearings put back in position with the bearing insert in place. At installation, the engine block and crankshaft must be adsorbed; main bearing oil clearance check with Plastigage, and the width of the crushed ones relative to the scale. When clearance is not as specified, check on cleanliness and if necessary, get rid of bearing insert. On the removal of all the Plastigage residues, lubricate bearing surfaces with thin layer of grease or engine assembly for sub sequent laying of crankshaft back into place. Replace new main bearing cap bolts and tighten the bolts successively in accordance with the torque specifications and the crankshaft end play should also be checked. Then, turn the crankshaft to see if it binds; it should rotate freely with a running torque no more than 50 in-chosen units and replace the rear main oil seal.

The lower crankcase is installed.