Usage:
D346, D348, D349 Engines In All Applications
According to field reports, some dealers and customers have installed replacement main and/or connecting rod bearings in the above model engines when the bearings were found to have cavitation erosion (see the illustration). Cavitation erosion is caused by normal rapid changes in oil pressure at specific locations on the bearing during engine operation. A pressure decrease permits the development of small bubbles in the oil which break when the pressure increases again. When the bubbles break, it causes the application of a force against the bearing surface. After many cycles, the application of force to the bearing metal causes small pieces of the lead-tin surface layer to come off as shown in the illustration. This is cavitation erosion.
Typical example of cavitation erosion.
Normally, cavitation erosion will not cause bearing failures for these reasons:
... The very small size and amount of debris caused by cavitation erosion.
... The location of the cavitation erosion on the bearing surface. The location is generally near the separation at the ends of the bearing as shown in the illustration; not in the "load area".
When cavitation erosion is found during an inspection of main and connecting rod bearings, the recommendation is to use the bearings again unless there are other indications of wear and/or damage.