Checking clearance in main bearings
Attention! Do not touch the liners with your fingers, as otherwise they may corrode prematurely.
2. Clean the outer surface of the new oil-grooved main bearings, and carefully insert them into the cylinder block bed (grooved bushings fit into the cylinder block, the lubrication holes in the bearing shells must be aligned with the holes in the cylinder block). Do not lubricate inserts.
3. Insert the thrust washers into the cover and into the groove of the bed of the cylinder block of the extreme rear crankshaft journal.
4. Wipe the surface of the earbuds with a clean, lint-free cloth.
5. Install the crankshaft in place and measure the clearances in the main journals. To do this, put a piece of calibration plastic wire on each crankshaft main journal parallel to its axis (see photo). Clean the surfaces of the liners in the covers, install the covers and evenly tighten the bolts in three steps to the specified torque. Unscrew the bolts and carefully lift the covers, compare the thickness of each of the crushed wires with the scale on the package and determine the gap (see photo).
6. If the gap is not correct, then the reason may be the wrong selection of the size group of the liners. Make sure there is no dirt or oil between the bearings and the cover surfaces when measuring (note that oil dissolves the wire!). If the width of the crushed wire at the ends is very different, then the crankshaft main journal has a taper.
Final crankshaft installation
7. Remove the remnants of the wire from the necks and remove the crankshaft.
8. Lubricate the main journals and thrust surfaces of the crankshaft with molybdenum grease. Install the crankshaft to the cylinder block. Lubricate the liners in the covers and install the covers with liners in their original places so that the arrows point towards the front of the engine. Lubricate also the thrust surface of the rear main bearing.
9. On a 7.4 liter engine until 1990, install the halves of the rear oil seal in the block bed and the rear main bearing cover.
10. Evenly, in 3 stages, tighten the bolts of all covers except the rear. Start tightening with the central bolts and move to the periphery. Tighten the rear cover bolts with a torque of 12-14 Nm. Lightly tap the crankshaft end with a lead or copper hammer in both directions to move the crankshaft so that the thrust surfaces of the main bearings and crankshaft are aligned. Loosen the cap bolts and tighten again to the specified torque in 3 stages, in the same order as the first tightening. If there are 4 bolts for fixing the covers, then first tighten the inner bolts, and then the outer ones.
11. On models with a manual transmission, install a guide bearing into the end of the crankshaft.
12. Turn the crankshaft a few turns - the crankshaft should rotate freely, without jamming.
13. Check the end play of the crankshaft (see above). If the thrust surfaces of the crankshaft are not worn out and new bearings are installed, then the play should be correct.
14. On engines V6, V8 5.0 and 5.7 liters, as well as 7.4 liters from 1991, install the crankshaft rear oil seal.