1999 Volvo Penta "WT" Models Workshop Manual, Page 71Get this manual
Crankshaft bearings for scoring or other damageIn general, the lower crankshaft bearings (except the #1 bearing) show the greatest wear and distress from fatigueUpon inspection, if lower crankshaft bearing is suitable for reuse, it can be assumed that the upper crankshaft bearing is also satisfactoryIf lower crankshaft bearing shows evidence of wear or damage, both the upper and lower crankshaft bearings must be replacedMeasuring Bearing Clearance Crankshaft bearings are of the precision insert type and do not use shims for adjustmentIf clearances are excessive, new upper and lower bearings will be requiredService bearings are available in standard size and undersizeRefer to Crankshaft and Bearing Installation in the proper engine repair sectionSelective fitting of crankshaft bearings are necessary in production to obtain close tolerancesFor example, you may find one-half of standard crankshaft bearing with one-half of an undersize crankshaft bearingTo determine the correct replacement bearing size, the bearing clearance must be measured accuratelyEither of the following two methods may be used, however, the micrometer method gives more reliable results and is preferredMicrometer Method ("