Nissan 12200-0W001 CRANKSHAFT Assembly

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Crankshaft removal is a process that can only happen after the engine has been removed from the vehicle and involves some prerequisites, like taking off the flywheel/driveplate, crankshaft pulley, timing belt (for 3.3L engines) or timing chain (for 2.4L and 3.5L engines), camshaft, crankshaft sprockets, oil pan, oil pump, and piston/connecting rod assemblies. In addition to this, before one embarks on crankshaft removal, it is important to examine the endplay of the crankshaft using dial indicators or feeler gauges. The dial indicator should be mounted with the stem in line with the crankshaft to contact one of its throws and zeroed out. After that, gently push back the crankshaft and observe the reading given by a dial indicator as this will indicate endplay. If there are excessive side clearances in excess of specifications then an investigation into wear on thrust surface of the crankshaft is required. If no wear is indicated then replacement of main bearing may cure end play problem. An alternative way to measure crankshaft end play uses feeler gauges to pry or push gently against the front face of the thrust bearing while placing feeler gauges between it and the front of the thrust bearing to determine how much clearance exists. Gradually loosen each main bearing cap bolt by turning it a quarter turn at a time in reverse order of tightening them until manoully removable bearing cap(s) and brace assembly are achieved.Normally cast-in arrows on main bear ing cap assembly indicate direction towards drivebelt end of engine but if these aren't there use number stamp or punch for marking cap assembly position/direction. Only mark front side of bearing cap brace when working on 3.3L engines because caps and brace are asingle unit.On 3.5L engines however, front part of bearing cap brace should be marked, removed and then inspected for installation marks on main bearing caps before they are removed from the engine. Notably, 2.4L engines do not include a main bearing cap brace. Theoretically, when loosening cap assembly from the engine block, you should be careful about losing bearing inserts in case they come out with the cap assembly. Thereafter, lift crankshaft out of the engine being cautious about its significant weight by preferably using help. Finally, put back cap assembly at its position ontheengineblockwiththebearinginsertsintactandtightenboltsfinger-tight.Incaseof3.5Lengines,the condition of main bearing cap bolts must be checked to ensure that there is no excessive stretching; if there is a difference of more than 0.0043 inch (0.11 mm) between indicated areas in bolt diameter, replace the bolts even complete sets if necessary.

For the final crankshaft installation, apply a thin, even layer of moly-base grease or engine assembly lube to the bearing surfaces and thrust faces.

Check the main and connecting rod bearing journals for uneven wear, scoring, pits, and cracks.

Clean the cap assembly bearing faces, install it with the arrow pointing toward the timing belt end, and tighten the bolts in three steps to the specified torque without rotating the crankshaft.

The prerequisites for crankshaft removal include the removal of the flywheel/driveplate, crankshaft pulley, timing belt (for 3.3L engines) or timing chain (for 2.4L and 3.5L engines), camshaft, crankshaft sprockets, oil pan, oil pump, and piston/connecting rod assemblies. The rear main oil seal retainer must also be unbolted and separated from the block.

The main bearing cap assembly features a cast-in arrow pointing to the timing belt end of the engine. Loosen the cap bolts gradually until the assembly can be removed by hand, ensuring to follow the reverse of the tightening sequence. Gently tap the cap assembly with a soft-face hammer to separate it from the engine block, using the bolts as levers if necessary, and take care not to drop the bearing inserts.

The main bearing cap assembly should be removed by gradually loosening the main bearing cap bolts in reverse order of their tightening sequence, by a quarter-turn each time. The cap assembly should be gently tapped and separated from the engine block, taking care not to drop the bearing inserts if they come out with the cap assembly.

To prepare for the main bearing oil clearance check, place new main bearing inserts into the main bearing saddles in the block, ensuring proper alignment with the oil holes in the block. Insert the flanged thrust bearing without lubrication, depending on the engine type.

Use a micrometer to measure the diameter of the main and connecting rod journals. Measure at multiple points around each journal's circumference.

Chamfering the oil holes prevents sharp edges from gouging or scratching the new bearings.

Install the main bearing caps with the arrows facing the drivebelt end of the engine. Gradually tighten the main bearing cap assembly bolts in three steps, starting from the center and moving outward. Avoid rotating the crankshaft during this process.

If the oil seal journals are worn or damaged, an automotive machine shop may be able to repair the journal by pressing on a thin sleeve. If repair is not feasible, a new or different crankshaft should be installed.