809144 Mercruiser COVER

START BY:a. remove oil pump 1. Check each main bearing cap (2) for its location on the engine. Each cap has an arrow (1) to show the front of the block and a number (3) which gives the location of that cap.2. Remove No. 2 through No. 4 main bearing caps from the engine. Remove the lower bearings from the caps.3. Remove the thrust plate from each side of the No. 3 upper main bearing.4. Turn the crankshaft until tool (A) can be installed in oil hole (4). Turn the crankshaft in the direction which will push the upper main bearing out, tab end first.
If the crankshaft is turned in the wrong direction, the tab of the bearing will be pushed between the crankshaft and the cylinder block. This will cause damage to the crankshaft and block.
Install the connecting rod bearings dry when the clearance checks are made. Put 2P2506 Thread Lubricant on the connecting rod bearings for final assembly.5. Install lower bearings in the bearing caps.6. Install upper bearings in the cylinder block with tool (A). Be sure tab (5) on the back of the bearings fits in the groove of the caps and cylinder block.
When bearing caps are installed, make sure the number on the side of the cap is next to and in alignment with the number on the engine block.
If the serviceman wants to measure the bearing clearances, Plastigage is recommended. Lead wire, shim stock or use of a dial bore gauge can damage the bearing surface.The serviceman must be very careful to use Plastigage correctly. The following points must be remembered:... Make sure that the backs of the bearings and the bores are clean and dry.... Make sure that the bearing locking tabs are properly seated in their slots.... The crankshaft must be free of oil where the Plastigage touches it.... If the main bearing clearances are checked with the engine upright or on its side, the crankshaft must be supported. Use a jack under an adjacent crankshaft counterweight, and hold the crankshaft against the crown of the bearing. If the crankshaft is not supported, the weight of the crankshaft will cause incorrect readings.... Put a piece of Plastigage on the crown of the bearing half that is in the cap. Do not allow the Plastigage to extend over the edge of the bearing.... Install the bearing cap using the correct torque-turn specifications. Do not use an impact wrench. Be careful not to dislodge the bearing when the cap is installed.... Do not turn the crankshaft with the Plastigage installed.... Carefully remove the cap, but do not remove the Plastigage. Measure the width of the Plastigage while it is in the bearing cap or on the crankshaft journal. Do this by using the correct scale on the package. Record the measurements.... Remove the Plastigage before installing the cap.When using Plastigage, the readings can sometimes be unclear. For example, all parts of the Plastigage are not the same width. Measure the major widths to make sure that they are within the specification range. Also, experience has shown that when checking clearances tighter than 0.10 mm (.004") the readings may be low by 0.013 to 0.025 mm (.0005 to .0010"). Out-of-round journals can give faulty readings. Also, journal taper may be indicated when one end of the Plastigage is wider than the other.For complete details concerning measuring bearing clearances, see Engine Bearings And Crankshafts, Form No. SEBD0531.7. Check the bearing clearance with tool (B) as follows:a. Put tool (B) in position on the surface of the lower main bearing. Do not turn the crankshaft when Plastigage (B) is in position.b. Put 2P2506 Thread Lubricant on the threads of the cap bolts. Install the caps and cap bolts, finger tight.c. Tighten the bolts on the tab end of the caps first to a torque of 260 14 N m (190 10 lb.ft.).
Do not use an impact wrench to tighten the bolts the additional 120°.
e. Put a mark across the bolt head and cap. Tighten the bolts opposite the tab end 120°. Tighten the bolts on the tab end of the cap 120° more. Make sure the main bearing caps are installed with their identification number (7) in alignment with the identification number on the left side of the cylinder block and arrow (6) toward the front of the block.8. Remove the main bearing caps and tool (B).9. Measure the thickness of the Plastigage to determine the bearing clearance. The clearance for new bearings must be 0.091 to 0.186 mm (.0036 to .0073 in.). The maximum clearance for used bearings is 0.25 mm (.010 in.).10. Install a thrust plate (8) on each side of the No. 3 upper bearing. Install the thrust plates with the side marked "BLOCK SIDE" toward the cylinder block.11. Install No. 2 through No. 4 main bearing caps.Follow the procedure in Step 7 to tighten the bolts.12. Do Steps 2, 4 through 9 and 11 for the No. 1 and No. 5 main bearings. 13. Check the end play of the crankshaft with tool (C). Make sure the dial indicator is against a machined surface. End play for new thrust plates must be 0.152 to 0.508 mm (0.006 to 0.020 in.). The maximum end play with used thrust plates is 0.89 mm (0.035 in.).END BY:a. install oil pump