INSERT 8J2281 - Caterpillar

In some applications, when the former crankshaft is to be used with the 9N1255 Cylinder Block Service Group, a front main bearing with an upper half that does not have a center groove can be needed. The locating tab on this bearing is also in the center. When the former crankshaft is to be used with a new 9N1255 Cylinder Block Service Group, always check the upper half of the front main bearing in the former cylinder block, or check the crankshaft to find out which type of No. 1 (front) main bearing is needed, before the crankshaft is installed. For crankshafts that have an oil supply passage from the No. 1 (front) main bearing journal to the No. 1 rod bearing, install the main bearing that has an upper half with a groove. For crankshafts that have an oil supply passage from the No. 2 main bearing journal to the No. 1 rod bearing, install the main bearing without a groove in the upper half.
GENERAL INSTALLATION: When a 9N2136, 9N2137 or 9N2138 Short Block Group, or a 9N1255 Cylinder Block Service Group is to be installed or is already installed, use the information that follows: The 9N1255 Cylinder Block Service Group has a front main bearing with a groove in the upper half and a locating tab in the center of the bearing. This bearing is the replacement for the earlier bearing that had an offset tab and a groove in the upper half of the bearing. Use Special Instruction Form GMG02555-01 to correctly install any of these replacement cylinder block groups.For late 3208 Engines which already have a cylinder block with a groove in the front main saddle and a front main bearing without a groove in the upper half of the bearing, use the information that follows:If a 9N1255 Cylinder Block Service Group is to be installed, do not use the 9N3070 Bearing sent with the group. Instead, use a front main bearing that does not have a groove in the upper half of the bearing. Again, use Special Instruction Form GMG02555-01 for correct installation instructions.
Comparison of narrow and wide design bearings.