GM 91177519 Engine Crankshaft (On Esn)

You can Select Your Vehicle to check if 91177519 fits your vehicle.

To initiate the engine reassembly process, assuming that the engine block and crankshaft have undergone cleaning, inspection, and necessary repairs, begin with the crankshaft installation. Position the engine with the bottom facing upward. Proceed by removing the main bearing cap bolts and gently lifting out the caps, arranging them in the correct order for accurate reinstallation. If the original bearing inserts are still in place, remove them from both the block and the main bearing caps. Ensure cleanliness by wiping the bearing surfaces on both the block and caps meticulously. Following this, clean the backsides of the new main bearing inserts and place one in each main bearing saddle within the block, ensuring proper alignment and fit without using lubrication. The flanged thrust bearings, if present, should be installed in the number three saddle. Clean the bearing surfaces on the crankshaft main bearing journals, and clean or inspect the oil holes in the crankshaft. Carefully position the crankshaft into place within the main bearings, ensuring cleanliness. Before finalizing the crankshaft installation, check the main bearing oil clearance using Plastigage. Cut appropriately sized Plastigage pieces and place one on each crankshaft main bearing journal, parallel to the journal axis. Install the main bearing caps or lower crankcase and progressively tighten the bolts as specified in the sequence for SOHC or DOHC engines. After removal of the caps or lower crankcase, compare the width of the crushed Plastigage on each journal to the provided scale to determine the main bearing oil clearance. Remove the Plastigage material and proceed to the final crankshaft installation step. Carefully lift the crankshaft out and ensure cleanliness of bearing faces in the block, then apply a thin, even layer of moly-base grease or engine assembly lube to all bearing surfaces and thrust bearings. Reinstall the crankshaft, apply lubricant to the bearing faces in the caps, and install them in their respective positions. Tighten the cap bolts according to the specified torquing sequence for SOHC or DOHC engines, ensuring proper alignment of thrust surfaces. Tap the crankshaft ends to align the main bearing and crankshaft thrust surfaces, then retighten all main bearing cap bolts to the specified torque. Check the crankshaft end play using a feeler gauge or a dial indicator to ensure it falls within acceptable limits, given that new bearings have been installed and the crankshaft thrust faces are free from damage.

Rubbing a penny across each journal can reveal its condition. If copper rubs off and embeds in the crankshaft, the journals may require regrinding.

Checking the end play of the crankshaft is important to ensure that it falls within specified limits. This measurement helps determine whether the thrust surfaces of the crankshaft are in good condition or if thrust bearings need to be replaced.