Mercury F1AZ-6V303-BRM Remanufactured Crankshaft Kit

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.

Remove burrs from crankshaft oil holes with stone/file/scraper. Chamfer oil holes to prevent bearing damage. Clean crankshaft with solvent and compressed air. Use brush to clean oil holes and flush with solvent. Rub penny on journals to check for copper embedding. Inspect for wear, scoring, pits, cracks. Magnaflux for hidden cracks. Measure journal diameter with micrometer for taper/out-of-round. Regrind if damaged/worn. Check oil seal journals for wear/damage. Repair or replace if necessary. Examine bearing inserts.

Mount a dial indicator with the stem in line with and just touching one of the crank throws. Push the crankshaft all the way to the rear and zero the dial indicator. Pry the crankshaft to the front as far as possible and note the reading on the dial indicator. The distance that it moves is the endplay. If the endplay is greater than specified, check the crankshaft thrust surfaces for wear. If no wear is evident, a new thrust bearing should correct the endplay. If the endplay is less than the minimum, check the thrust bearing surfaces for deep scratches, burrs, nicks, and dirt.

Clean the back sides of the new main bearing inserts and lay one bearing half in each main bearing saddle in the block. Lay the other bearing half from each bearing set in the corresponding main bearing cap. Make sure the tab on the bearing insert fits into the recess in the block or cap. Also, the oil holes in the block must line up with the oil holes in the bearing insert. Do not hammer the bearing into place and don't nick or gouge the bearing faces. No lubrication should be used at this time.

Using a micrometer, measure the diameter of the main and connecting rod journals and compare the results to the Specifications. Measure the diameter at several points to detect taper and out-of-round conditions. Take measurements at each end of the journal, near the crank throws, to determine if the journal is tapered. Crankshaft runout should also be checked, but large V-blocks and a dial indicator are needed to do it correctly. If you don't have the equipment, have a machine shop check the runout.

The original bearing inserts are removed if still in place, and new ones are laid in the main bearing saddles and caps during crankshaft installation.

Rotate the crankshaft a number of times by hand to check for any obvious binding.

The number five main bearing cap is the thrust bearing location and has upper and lower thrust bearing halves. It is bolted to the block with two main cap bolts; no jack screws or side bolts are used, although it is drilled for jack screws.