Mercury E3AZ-6303-B Crankshaft Assembly

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The crankshaft can only be removed after the engine has been taken out of the vehicle, assuming that the flywheel or driveplate, front crankshaft pulley, timing chain and sprockets, oil pan, oil pump, and piston/connecting rod assemblies have already been detached. First, check the endplay by mounting a dial indicator with the stem aligned and just touching one of the crank throws. Push the crankshaft to the rear and zero the dial indicator, then pry it to the front and note the reading; the movement indicates the endplay. If it exceeds specifications, inspect the crankshaft thrust surfaces for wear, and if no wear is found, a new thrust bearing may resolve the issue. For endplay less than the minimum, examine the thrust bearing surfaces for scratches, burrs, nicks, and dirt. If a dial indicator is unavailable, feeler gauges can be used by prying or pushing the crankshaft to the front and slipping the gauges between the crankshaft and the thrust main bearing to measure clearance. The thrust bearing is located in the number 5 bearing saddle on 4.9L engines and in the number three bearing saddle on V6 and V8 engines. Check the main bearing caps for markings indicating their locations, which should be numbered consecutively from front to rear; if not, mark them using number stamping dies or a center-punch, ensuring to make the punch marks near one of the bolt heads. Loosen the main bearing cap bolts gradually until they can be removed by hand, then gently tap the caps with a soft-face hammer to separate them from the engine block, using the bolts as levers if necessary while avoiding dropping the bearing inserts. Carefully lift the crankshaft out of the engine, ideally with assistance due to its weight, and with the bearing inserts in place, return the caps to their original locations on the block and tighten the bolts finger tight. Finally, remove the Woodruff key from the crankshaft nose to prevent loss, or leave it in place if difficult to remove.

Check the rest of the crankshaft for cracks and other damage. It should be magnafluxed to reveal hidden cracks, a procedure typically handled by an automotive machine shop.

If the clearance is not as specified, the bearing inserts may be the wrong size (which means different ones will be required). Before deciding that different inserts are needed, make sure that no dirt or oil was between the bearing inserts and the caps or block when the clearance was measured. If the Plastigage was wider at one end than the other, the journal may be tapered.

Remove all side bolts.

Rubbing a penny lengthwise on each journal will reveal its condition. If copper rubs off and is embedded in the crankshaft, the journals should be reground. If a journal picks up copper from the penny, it's too rough and must be reground.

Tighten the main bearing cap bolts in two steps in the sequence shown and to the torque and angle indicated in the Specifications listed at the beginning of the Chapter.

Clean the faces of the bearings in the block and the crankshaft main bearing journals with a clean, lint-free cloth. Check or clean the oil holes in the crankshaft, as any dirt here can only go one way - straight through the new bearings!

1. Gently pry or push the crankshaft all the way to the front of the engine. 2. Slip feeler gauges between the crankshaft and the front face of the thrust main bearing to determine the clearance. 3. The thrust bearing is the number 5 bearing saddle on 4.9L engines and in the number three bearing saddle on V6 and V8 engines.

Check the rest of the crankshaft for cracks and other damage. It should be magnafluxed to reveal hidden cracks, a procedure typically handled by an automotive machine shop.