Caution: Before removing the crankshaft, the following must be removed: flywheel, oil pan, oil pump, pistons with connecting rods and rear oil seal housing.
Before removing the crankshaft, check the play of the shaft end. Install the gauge with the indicator coaxially with the shaft and rest the gauge rod against the end.
Press the shaft back as far as it will go and set the indicator to zero. Then press the shaft forward as far as it will go and record the arrow reading, which is equal to the clearance. If the clearance is greater than the permissible value, check the wear of the shaft thrust surfaces. If no wear is detected, the clearance can be reduced by installing new main bearings.
The clearance can also be measured using feeler gauges. Press the shaft forward as far as it will go. Insert feeler gauges between the shaft and the front surface of the main bearing. Check if the main bearings are marked. They should be numbered sequentially from the front of the engine to the rear. If there are no marks, make marks with a center punch.
Often there is an arrow on the caps that points forward. If there is not, draw an arrow with a marker before removing the caps. Loosen the cap bolts in ¼-turn increments until they can be removed by hand.
Tap the caps gently with a soft-faced hammer, then remove them from the cylinder block. If necessary, use the bolts as leverage to remove the caps. Be careful not to drop the bearing shells.
Carefully remove the crankshaft from the engine. Replace the bearing shells, install the bearing caps and tighten the bolts by hand.