GM 12588614 Engine Crankshaft

The crankshaft can only be accessed if the entire engine has been pulled out of the car accompanied with conditions such as; flywheel, crankshaft pulley, timing chain, engine oil pan, oil pump, oil filter, piston and connecting rod assemblies being removed. Before removing the crankshaft, face the crankshaft and with the help of dial indicator fix the end play of the crank shaft. With the crankshaft front (throws away from the water pump), set the indicator to zero; then, moving the shaft to the rear (throws towards the water pump), take the reading; the endplay should measure between 0.003 and 0.010 inches. If a dial indicator is not available feeler gauges can be used in order to measure clearance. Gradually undo the main bearing cap bolts, give the assembly a gentle tap with a soft-face hammer and then raise off the assembly. While lifting the crankshaft there is always advisable to do it with help because of its size. Before installing the crankshaft, clean both compartments of the engine block and the crankshaft and then turn the block upside down, take the main bearing cap assembly off, and clean the associated bearing surfaces. New upper main bearing inserts should be installed and checked for proper alignment of oil holes and also the thrust washers should be placed properly depending on the type of engine used. Clean the lower bearing inserts and they are then fitted into the main bearing cap assembly; they must fit perfectly and without any signs of wear or tear. Following the cleaning of the crankshaft, the crankshaft should be laid on the block and the main bearing oil clearance should be determined using Plastigage. The main bearing caps must be fitted without moving the Plastigage and the bolts must be tightened in the pattern that is recommended. The caps must be unscrewed to measure the Plastigage and to check the clearance; if beyond the limit, check for any interference, dirt or oil and if inserts are worn out they must be changed. Remove the Plastigage from the journals and bearing faces and lubricate the bearing surfaces with the assembly lube or fresh grease before putting back the crankshaft. Bolt the caps of the main bearing in position such that the arrows are facing forward, and tighten all the bolts. Check and recheck the crankshaft end-play and turn the crankshaft with your hands so that it can move with ease. Last of all, fit the new rear main oil seal into its respective position and sequence the engine as prescribed whereby the oil seal is fastened towards the front of the engine, so that the crankshaft will push it firmly into position.

The crankshaft can be removed only if the engine is pulled out of the vehicle presuming that the driveplate, crankshaft pulley, oil pan, timing chain, and piston/connecting rod assemblies have been removed. Prior to crankshaft removal, check and record crankshaft end play with a dial indicator placed in line with the crankshaft. Move the crankshaft to the rear and bring the indicator to zero and then move the crankshaft to the front and check the new reading which should normally be between 0.003 to 0.010 inch. If a dial indicator cannot be used, clearance may be measured using feeler gauges as can be observed in Fig. Tighten the main bearing cap bolts gradually until they are lightly seized, then remove the main bearing cap stiffener and if necessary mark the caps 1 & 2. It is safer to lift out the crankshaft, if possible with aid, and fit the main bearing caps and the stiffener very loosely but the correct way around. Bearing in mind installation, the block should be oriented such that it's resting on its bottom end; you will also need to pull out any stock bearing inserts and clean the bearing housing machined surfaces. Place new upper main bearing inserts into the main bearing saddles and make certain that oil holes coincide; fit the thrust washer to the number 5 crankshaft journal. Scrub the crankshaft and the insert end of the bearing and put the crankshaft into place. Inspect the oil clearance of the main bearing with the Plastigage installed; it should be installed just slightly less than the width of the journal and tighten the main bearing cap assembly without disturbing the Plastigage. In the designed sequence, further tighten the bolts and then take out the bolts and with the help of scale measure the Plastigage width. If the clearance is wrong it is wise to check for cleanliness and also consider having a change in the bearing inserts. It is always recommended that once Plastigage has been scraped off one should apply a thin coat of grease or assembly lube to the bearing surface as well as the thrust faces and re-fits crankshaft and main bearing cap. Loosening of bolts results into incorrect crank shaft end play so tighten the bolts and check end play and see that it is correct. Try and turn the crankshaft by hand so as to check for tightness, and if okay go ahead and fit the new rear main oil seal.

Scrape off any Plastigage residue and lift the crankshaft out of the cylinder block. Apply lubricant to the bearing surfaces and lay the crankshaft back in place. Apply lubricant to the bearing insert faces and clean the engine block and bearing cap mating surfaces. Apply clean engine oil to all bolt threads and tighten the main bearing cap bolts to the specified torque.

For installation, ensure the engine block and crankshaft are clean and inspected. Position the block upside down, remove any original bearing inserts, and clean the surfaces thoroughly.

Mount a dial indicator and touch the end of the crankshaft. Pry the crankshaft to the rear and zero the dial indicator, then pry it to the front and check the reading.

Remove the bolts and lift off the main bearing caps, then compare the width of the crushed Plastigage to determine the main bearing oil clearance.

Scrape off any Plastigage residue and lift the crankshaft out of the cylinder block. Apply lubricant to the bearing surfaces and lay the crankshaft back in place. Apply lubricant to the bearing insert faces and clean the engine block and bearing cap mating surfaces. Apply clean engine oil to all bolt threads and tighten the main bearing cap bolts to the specified torque.

Finally, install the new rear main oil seal in the retainer, but wait to install the retainer until the balance shafts are in place.

Position the engine block with the bottom facing up and remove the main bearing caps. Clean the bearing surfaces and install new bearing inserts. Check the main bearing oil clearance using Plastigage. Apply clean engine oil to all bolt threads and tighten the bolts to the specified torque.

Remove the bolts and lift off the main bearing caps, then compare the width of the crushed Plastigage to determine the main bearing oil clearance.