Main Bearing And Cylinder Bore

MAIN BEARING INSPECTION 

Courtesy of CHRYSLER GROUP, LLC

1. Wipe the main bearing inserts clean.
2. Inspect the inserts for abnormal wear patterns, scoring, grooving, fatigue, pitting and for metal or other foreign material imbedded in the lining.
3. Inspect the back of the inserts for fractures, scrapes or irregular wear patterns.
4. Inspect the insert locking tabs for damage.
5. Inspect the crankshaft thrust washers for scoring, scratches, wear or blueing.
6. Replace any bearing that shows abnormal wear.
7. Inspect the main bearing bores for signs of scoring, nicks and burrs.
8. If the cylinder block main bearing bores show damage, replace the engine block.

   Courtesy of CHRYSLER GROUP, LLC

   1 - Point (A) 90° From Crankshaft Axis (B)

   2 - Cylinder Bore Gauge

   3 - Cylinder Bore

   4 - Cylinder Bore Measuring Area

CYLINDER BORE INSPECTION 

1. Use a cylinder bore gauge to correctly measure the inside diameter of the cylinder bore. A cylinder bore gauge capable of reading in 0.003 mm (0.0001 in.) Increments is required. If a bore gauge is not available, do not use an inside micrometer.
2. Measure the inside diameter of the cylinder bore at three levels below the top of the bore. Start at the top of the bore, perpendicular (across or at 90°) to the axis of the crankshaft at point A.
3. Repeat the measurement near the middle of the bore then repeat the measurement near the bottom of the bore.
4. Determine the taper by subtracting the smaller diameter from the larger diameter.
5. Rotate the measuring device 90° to point B and repeat the three measurements. Verify that the maximum taper is within specification. Refer to ENGINE SPECIFICATIONS .
6. Determine out-of-roundness by comparing the difference between each measurement. Verify that the out-of-roundness is within specification. Refer to ENGINE SPECIFICATIONS .
7. If the cylinder bore taper and out-of-roundness does not exceed specification, then the cylinder bore can be honed. If the cylinder bore taper or out-of-round condition exceeds the maximum limits, replace the cylinder block.