Detroit Diesel 4000 Series, Service Manual, Page: 416 / 2706

SERIES 4000 12/16V SERVICE MANUAL
1. In new condition, the running surface is approximately 75% wear layer (1), approximately
25% intermediate layer (2) and approximately 5% run-in layer (3), corresponding to 1 —
3 mm (0.0393 —0.1181 in.) sputtered. See Figure 195.
1. Wear Layer 3. Run-In Layer
2. Intermediate Layer
Figure 195 Checking and Assessing Main Bearing Shells
2. Wear of the bearing running surfaces starts at the galvanized wear layer (1). See Figure 195.
3. The wear layer in the groove is removed by some 0.0001 mm (0.000039 in.).
4. The difference between intermediate layer (2) and wear layer (1) for further wear remains
approximately constant at roughly 0.005 mm (0.00275 in.). See Figure 195.
NOTE:
A magnifying glass is required for a more accurate assessment of the wear condition of
the running surface (magnification minimum 5x).
5. The wear layer is seen as a dark zone and the intermediate layer as a light zone. The
decisive factor for the wear condition of the grooved bearing is the ratio "width of
intermediate layer: width of groove" and the extent of the worn surface.
6. The sputtered bearing is still functional if the wear layer is partially missing in the
grooves. Practice has shown that the sputtered bearing with partially empty grooves can
continue in use without negatively affecting bearing function.
All information subject to change without notice.
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