Jeep 4781643AA CRANKSHFT

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The crankshaft can only be removed if the engine has been pulled out of the vehicle, provided other parts such as flywheel, crankshaft pulley, timing belt, oil pan, oil pump body, oil filter, balance shafts, carrier assembly and piston/connecting rod assemblies have been removed. As a preparation to the crankshaft removal, the crankshaft end play should be determined by inserting a dial indicator on the crankshaft. Move the crankshaft to the rear, set indicator to zero then move the crankshaft to the front and take the reading it should be between 0.003 and 0.010 inches. Feelers gauges can be used if dial indicator is absent in order to measure clearance. Screw out the main bearing cap assembly bolts slowly and then you can almost take it out with your hand, you only have to hit the bracket gently with a soft padded hammer and lift it up, do not drop the bearings. Slowly raise the crankshaft out, if possible in coordination with another person because of its mass. For installation, it becomes relevant to be certain that the engine block and the crankshaft need to be clean and examined. Align the block in the manner that the bottom is upwards, unbolt the main bearing cap assembly and then clean the bearing areas. New upper main bearing inserts to be fitted in the block and lower inserts in the cap assembly, with correct alignment of oil groves and holes. It is recommended to use Plastigage, and check whether the oil clearance is within the appropriate range. If required, it might be necessary to change the bearing inserts with the ones of appropriate size. Cleans all the bearing surfaces, next, put a thin layer of oil on the bearing insert and the thrust faces and then replace the crankshaft. Screw on the main bearing assembly in the crankshaft and block in the right position and tighten the bolt to the required torque for the right sequence. As far as certain types of engines are concerned, it is required to use certain tightness coefficients and to examine crankshaft end-float. Last begin the crankshaft and turn it for binding for better and smooth rotation before fitting the new rear main oil seal.

The crankshaft can only be removed after the engine has been taken out of the vehicle, and after components such as the flywheel, crankshaft pulley, timing belt or chain, oil pan, oil pump body, oil filter, and piston/connecting rod assemblies have been detached.

Measure the crankshaft endplay using a dial indicator aligned with the crankshaft. Pry the crankshaft to the rear, zero the indicator, then pry it to the front to check the reading, which should typically be between 0.003 to 0.010 inch. If a dial indicator is unavailable, feeler gauges can be used to determine clearance.

The bearing faces in the block and crankshaft main bearing journals should be cleaned, and the oil holes in the crankshaft should be checked or cleaned.

Clean the crankshaft with solvent and dry it with compressed air if available.

Check the main bearing caps for markings indicating their locations, which should be numbered consecutively from front to rear. If they are not marked, use number stamping dies or a center-punch to mark them, ensuring to make the punch marks near one of the bolt heads.