812421A13 Mercruiser MC IV SSM

start by:a) remove oil pan plateb) remove oil pump 1. Remove the Nos. 1, 3 and 5 main bearing caps (1). Remove the crankshaft thrust bearings from No. 7 main bearing. Remove lower halves of bearings (2) from the caps.
If the crankshaft is turned in the wrong direction, the tab on bearing will be pushed between the crankshaft and bearing area in block which can cause damage to the block or crankshaft.
2. Install tool (A) in the oil hole in the crankshaft journal and remove upper main bearing halves as the crankshaft is turned and the bearing is moved out of the cylinder block. Do not put oil on the bearing until after the bearing clearance is checked.3. Put clean engine oil on the upper bearing halves. Use tool (A) to push the upper halves of the main bearings in place. Put clean engine oil on the new crankshaft thrust bearings and install the bearings with the grooves in the bearings against the crankshaft.
Make sure the upper and lower halves of bearings are installed so the bearing tabs fit into the notch in cylinder block and bearing caps.
4. Clean main bearing caps (1) and install lower bearing halves (2). Put clean engine oil on the bearings, bolt threads and surfaces that make contact with the washers. When the bearing clearance is checked and the engine is in a vertical position, such as in the vehicle, the crankshaft will have to be lifted up and held against the upper halves of the main bearings to get a correct measurement with the Plastigage. The Plastigage will not hold the weight of the crankshaft and give a correct indication. If the engine is in a horizontal position, it is not necessary to hold the crankshaft up. Do not turn the crankshaft when the Plastigage is in position to check clearances.5. Check the bearing clearance with Plastigage as follows: a) Put a piece of the Plastigage (B) on the surface of the lower bearing half. Make sure part number on cap is toward front of engine and number on bottom of cap is the same as number on cap saddle when the caps are installed. b) Install caps (1) and tighten the bolts to a torque of 30 3 lb.ft. (40 4 N m).c) Put a mark on each bolt and cap, then tighten the bolts 90° more.d) Remove the cap. Measure the width of the Plastigage. The main bearing clearance must be .0030 to .0065 in. (0.076 to 0.165 mm). Maximum permissible clearance with used bearings is .010 in. (0.25 mm).6. Put clean engine oil on the bearings and crankshaft.7. Install bearing caps (1) and tighten the bolts as in Steps 5b and 5c.9. Check the crankshaft end play with tooling (C). The end play is controlled by the thrust bearings on the No. 7 main bearing. End play with new bearings is .0025 to .0145 in. (0.064 to 0.368 mm). The maximum permissible end play with used bearings is .025 in. (0.64 mm). Spacer Plate engines have thrust bearings with a tab that fits into a machined area in the cylinder block for correct installation. Always install thrust plates with the identification "BLOCK SIDE" next to the cylinder block.end by: a) install oil pumpb) install oil pan plate