FLYWHEEL AS 4P6818 - Caterpillar

Remove And Install Crankshaft Main Bearings
Start By:a. remove oil pump1. Check the main bearing caps for identification for their location and direction in the block. The caps must be installed in the same location and direction from which they were removed. Remove No. 2 thru No. 6 bearing caps (1). Remove the thrust plates for the No. 4 main bearing.
If the crankshaft is turned in the wrong direction the tab of the bearing will be pushed between the crankshaft and cylinder block. This can cause damage to either the crankshaft or cylinder block or both.
3. Remove the upper halves of the main bearings by putting tool (A) in oil hole (2) in the crankshaft. Turn the crankshaft in the direction which will push the end of the bearing with a tab out first.4. Remove the lower halves of the bearings from the caps. Install the bearings dry when the clearance checks are made. Put clean engine oil on the bearings for final assembly.5. Install the new bearings in the caps.6. Install the upper halves of the bearings in the cylinder block with tool (A). Be sure tabs (3) on the back of the bearings fit in the tab slots of the caps and cylinder block.The servicemen must be very careful to use Plastigage, tool (B) 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 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") 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 on end of the Plastigage