STANDARD PROCEDURE
MAIN BEARING FITTING
SELECT FIT IDENTIFICATION
The main bearings are “select fit” to achieve proper oil clearances. For main bearing selection, the crankshaft position sensor target wheel (2) has grade identification marks (3) stamped into it. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4. The crankshaft position sensor target wheel (2) is mounted to the number 6 counter weight (1) on the crankshaft.
INSPECTION
Wipe the inserts clean and inspect for abnormal wear patterns and for metal or other foreign material imbedded in the lining. Normal main bearing insert wear patterns are illustrated.
Inspect the back of the inserts for fractures, scrapings or irregular wear patterns.
Inspect the upper insert locking tabs for damage.
Replace all damaged or worn bearing inserts.
MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT REMOVED)
Remove the crankshaft from the cylinder block (Refer to 9 - ENGINE/ENGINE BLOCK/CRANKSHAFT - REMOVAL).
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal with a micrometer. Measure at two locations 90° apart at each end of the journal.
The maximum allowable taper is 0.008mm (0.0004 inch.) and maximum out of round is 0.005mm (0.002 inch). Compare the measured diameter with the journal diameter specification (Main Bearing Fitting Chart). Select inserts required to obtain the specified bearing-to-journal clearance.
Install the crankshaft into the cylinder block (Refer to 9 - ENGINE/ENGINE BLOCK/CRANKSHAFT - INSTALLATION) .
Check crankshaft end play.
CRANKSHAFT MAIN BEARING SELECTION
1. Service main bearings are available in four grades. The chart below identifies the four service grades available.
| Crankshaft Marking | JOURNAL SIZE SIZE mm (in.) | |
| "R" Size | 63.488 - 63.496
mm (2.4995 - 2.4998 in.) | |
| "S" Size | 63.496
- 63.500 mm (2.4998 - 2.4999 in.) | |
| "T" Size | 63.500 -
63.504 mm (2.4999 - 2.501 in.) | |
| "U" Size | 63.504 - 63.512
mm (2.5001 - 2.5004 in.) | |
| Bearing size | ||
| Bearing
Code | Size | Application |
| Upper Bearing | ||
| A | .2.443 - 2.447 mm | Use with crankshaft size "R" |
| (.0961 - .0963 in.) | ||
| B | 2.439 - 2.443 mm | Use with crankshaft "S, T" |
| (0.960 - .0961 in.) | ||
| C | 2.435 - 2.439 mm | Use with crankshaft "U" |
| (.0958 - .0960 in.) | ||
| Lower Bearing Main "1" and "4" | ||
| "1" | 2.441 - 2.447 mm | Use with crankshaft "R, S" |
| (.0961 -.0963 in.) | ||
| "2" | 2.435 - 2.441 mm | Use with crankshaft "T, U" |
| (.0958 - .0962 in.) | ||
| Lower Main Bearing "2" and "3" | ||
| "3" | 2.429 - 2.435 mm | Use with crankshaft "R, S" |
| (.0956 - .0958 in.) | ||
| "4" | 2.423 - 2.429 mm | Use with crankshaft "T, U" |
| (.0953 - .0956 in.) | ||
| Bearing Clearances | ||
| Main "1, 4" | ||
| Crankshaft "R" | .004 - .034
mm ( .00015 - .0013 in.) | |
| Crankshaft "S" | .004 - .030 mm
( .00015 - .0011 in.) | |
| Crankshaft "T" | .006 - .032 mm (.0002
- .0012 in.) | |
| Crankshaft "U" | .002 - .032 mm (.00007 - .
0012 in.) | |
| Main "2, 3" | ||
| Crankshaft "R" | .016 - .046 mm (.0006 - .0018 in.) | |
| Crankshaft "S" | .016 - .042 mm (.00062 - .016 in.) | |
| Crankshaft "T" | .018 - .044 mm (.0007 - .0017 in.) | |
| Crankshaft "U" | .014 - .044 mm (.0005 - .0017 in.) | |