Ford F4ZZ-6303-ARM Crankshaft Assembly

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Crankshaft installation is the first step in engine reassembly. The engine is flipped upside down, main bearing caps are removed, and new bearing inserts are placed. The crankshaft is carefully positioned and oil clearance is checked. The caps are installed and torqued in three steps. Grease is applied to the bearing surfaces and the crankshaft is placed back into the block. Crankshaft rotation and endplay are checked. For OHC engines, jack screws are used and the rear main oil seal is installed.

Inspect the endplay using a dial indicator or feeler gauges before taking out the crankshaft. If the endplay is more than the limit, then check for wear on crankshaft thrust surfaces. If necessary, label and number main bearing caps. On OHV engines begin from the center and loosen main bearing cap bolts gradually. In order to take off the crankshaft in OHC engines, follow this exact process. Replace main bearing cap bolts and lift out the crankshaft gently. Put back the caps in their original positions on the engine block and finger tighten their bolts.

Rub a penny across each journal. If copper rubs off and is embedded in the crankshaft, the journals should be reground.

Carefully lift the crankshaft out of the engine. It's a good idea to have an assistant available, since the crankshaft is quite heavy.

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 burrs from the crankshaft oil holes with a stone, file, or scraper. The oil holes should be chamfered so sharp edges don't gouge or scratch the new bearings.