GM 91177510 Engine Crankshaft (On Esn)

Remove all burrs from the crankshaft oil holes with a stone, file or scraper, ensuring the oil holes are chamfered to prevent damage to new bearings. Check the main and connecting rod bearing journals for uneven wear, scoring, pits and cracks. Rub a penny across each journal several times to reveal its condition-if copper rubs off and is embedded in the crankshaft, the journals should be reground. Clean the crankshaft with solvent and dry it with compressed air, using a stiff brush to clean the oil holes and flush them with solvent. Check the rest of the crankshaft for cracks and other damage, which should be revealed by mag-nafluxing. Measure the diameter of the main and connecting rod journals with a micrometer and compare the results to the Specifications. If the crankshaft journals are damaged, tapered, out of round or worn beyond the limits given in the Specifications, have the crankshaft reground by an automotive machine shop and use the correct size bearing inserts if the crankshaft is reconditioned. Check the oil seal journals at each end of the crankshaft for wear and damage. If the seal has worn a groove in the journal, or if it's nicked or scratched, the new seal may leak when the engine is reassembled. In some cases, an automotive machine shop may be able to repair the journal by pressing on a thin sleeve. If repair isn't feasible, a new or different crankshaft should be installed. Examine the main and rod bearing inserts.

Engine removal is the only way to remove a crankshaft. The end play should be checked before the removal of the crankshaft. With a stem in line with the crank and touching one of the crank throws, mount a dial indicator on it. Zero the dial indicator upon pushing the crank all to the rear then pry it as far as possible and read from the dial indicator to determine end play. Examine for wear of thrust surfaces in case end play is greater than that specified. If no wear is apparent, new thrust bearings will correct this condition. Feeler gauges can also be used if there is no dial indicator. To check clearance between its front face of thrust bearing and its crankshaft, gently push or pry it to engine front direction (towards you) and slip feeler gauges in between them. SOHC engines must have their main bearing caps checked as they may be marked. From front towards back, these should be numbered consecutively. In case they are not marked, number stamping dies or center punches should be used to mark them. While noting stud bolts positions, gradually loosen and remove main bearing caps by hand; gently separate caps from engine block using soft-face hammer taps. Crankshaft's main bearings do not have caps on DOHC engines but instead block uses "lower crankcase" to hold it in place. In order remove lower crank-case screws have to be taken out according to indicated sequence following which care must be taken due to its weight as the author states . Gently lift out the Crankshaft being mindful of how heavy it is when removing it from an engine bay. The caps need to return into their proper places on an engine block together with bearing inserts located within an engine block so that bolts can be tightened finger tight.