28642 Mercruiser SCREW, WATER PUMP DRIVE (1/4")

To prevent damage to the intake and exhaust valves an adjustment must be made to the valve clearance setting. Loosen the nuts on each rocker arm, and move the adjustment screw on each rocker arm away from the bridge as far as possible.
1. Put the engine in position on Tooling (A). Use Tooling (A) to turn the engine so that the crankshaft is up as shown.2. Remove the breather tube and the air cleaner housing and support from the left side of the engine (as seen from the flywheel end of the engine).3. Turn the engine over on its side. Make sure the blocks that are used as support for the top of the engine are against the cylinder head only and not against the exhaust manifold or valve cover bases. 4. Loosen the nuts that hold each connecting rod bearing cap (1) in position. Turn the crankshaft if necessary to loosen all the nuts. Make sure the nuts are still tight enough to hold the bearing caps in place when the crankshaft is turned. 5. Turn the crankshaft so that "V" mark (2) on the crankshaft gear is in alignment with "V" mark (3) on the idler gear.6. Remove the bearing caps that hold the connecting rods in position against the crankshaft. 7. Remove bearings (4) from each bearing cap. Make sure that each bearing is kept with the bearing cap it is removed from for correct installation purposes. 8. Remove all crankshaft main bearing caps (5).9. Push the pistons are far away as possible from the crankshaft. 10. Remove bearing (6) from each crankshaft main bearing cap. Make sure that each bearing is kept with the crankshaft main bearing cap it is removed from for correct installation purposes. 11. Remove two thrust plates (7) from the center main bearings. 12. Fasten Tooling (B) and a hoist to the crankshaft as shown.13. Use Tooling (B) and a hoist to remove crankshaft (8) from the cylinder block. The weight of the crankshaft is approximately 131 kg (290 lb). Lift the crankshaft slowly so the main bearing upper halves stay in the cylinder block. 14. Use Tool (C) to remove gear (9) from the crankshaft. Use Tooling (D) to remove the dowel that is under the gear if a replacement of the dowel is necessary. 15. Use Tooling (E) to remove pin (10) from the crankshaft if a replacement of the pin is necessary. 16. Put identification on main bearing upper halves (11) and connecting rod bearing upper halves (12) as to their location in the cylinder block and connecting rods. Remove bearings (11) and (12).17. Check the condition of the main bearings and crankshaft. Make reference to Guideline For Reusable Parts: Main & Connecting Rod Bearings, SEBF8009 and Visual Inspection of Crankshafts, SEBF8043.Install Crankshaft
If the crankshaft journals and bores for the block and rods were measured at disassembly and found to be within specifications, no further checks are necessary. However, if the serviceman still 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.... 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.... If the main bearing clearances are checked with the engine upright or on its side, the crankshaft will have to be lifted up with a force equal to the weight of the crankshaft and held against the crown of the bearing. If the crankshaft is not supported, the weight of the crankshaft will cause incorrect readings.... 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 reinstalling 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 in) the readings may be low by 0.013 to 0.025 mm (.0005 to .0010 in). Out-of-round journals can give faulty readings. Also, journal taper may be indicated when one end of the Plastigage is wider that the other. For complete details concerning measuring bearing clearances, see Engine Bearings & Crankshafts, SEBD0531. Do not put oil on the bearings until the bearing clearance has been checked.1. Install bearings (1) in the connecting rods they were removed from. Make sure the tab in each bearing is in alignment with the notch in each connecting rod.2. Install bearings (2) in the cylinder block. Make sure the tab in each bearing is in alignment with the notch in the cylinder block. 3. Install pin (3) in the end of the crankshaft. Install the pin so that it extends a maximum of 6.4 mm (.252 in) above the surface. 4. Install the dowel in the crankshaft that puts gear (4) in the correct position. Install the dowel so that it extends 4.1 0.5 mm (.161 .020 in) above the surface of the crankshaft.5. Heat gear (4) to a maximum temperature of 233° C (451° F). Gear (4) must be installed on the crankshaft with the "V" timing mark toward the