21638 Mercruiser BEARING (Upper)

1. Turn the crankshaft until the "C" mark on the crankshaft gear is in alignment with the "C" mark on the camshaft gear as shown. The main bearing caps are installed with the part number toward the front of the engine. Each cap has a number on the bottom of the cap, which is the same as the number on the camshaft side of the cylinder block. 2. Remove the three center main bearing caps and thrust bearing.3. Install one of the flywheel bolts in the end of the crankshaft. Fasten a hoist.4. Remove the two end caps.
Be extra careful not to cause damage to the crankshaft journals when the crankshaft is removed.
5. Remove the crankshaft. The weight is 100 lb. (45 kg).6. Remove the crankshaft main bearings from the cylinder block and from the main bearing caps. 7. Install tooling (A) and remove the gear from the crankshaft.Install Crankshaft And Gear
1. Heat the crankshaft gear to a maximum temperature of 600°F (315°C). Install the gear on the crankshaft with the "C" mark on the gear toward the pulley end of the crankshaft.2. Clean the area for the main bearings in the caps and block. 3. Install upper main bearings (1) (the bearing with oil hole) in the block and the lower main bearings in the caps. Put clean engine oil on the bolt threads.4. Fasten a hoist and put the crankshaft in position in the cylinder block with the timing marks on the camshaft gear and crankshaft gear in alignment.
When bearing caps are installed, make sure the caps are installed with the part number toward the front of the engine and the number on the bottom of the cap is the same as the number on the camshaft side of the engine.
5. Install thrust main bearing (2) and all the caps. Tighten the bolts to a torque of 120 10 lb.ft. (160 14 N m). When the bearing clearance is checked with the engine in a vertical position, the crankshaft will have to be pushed against the upper halves of the main bearings and held to get a measurement. The Plastigage will not hold the weight of the crankshaft. 6. Check bearing clearance by removal of cap and installation of Plastigage (A) between crankshaft and bearing. Tighten bolts to a torque of 120 10 lb.ft. (160 14 N m). Remove cap and check thickness of Plastigage. Bearing clearance must be .0030 to .0066 in. (0.076 to 0.168 mm). The maximum permissible clearance is .010 in. (0.25 mm).7. Put clean engine oil on the bearings and crankshaft journals. Install main bearing caps. Tighten to a torque of 120 10 lb.ft. (160 14 N m). 8. Check the crankshaft end clearance with tooling (B). The clearance is controlled by the thrust main bearing. End clearance of the crankshaft must be .0025 to .0190 in. (0.064 to 0.483 mm). The maximum permissible clearance with used bearing is .035 in. (0.89 mm).end by:a) install pistonsb) install timing gear coverc) install flywheel housing