4943979 3935349 Engine Connecting Rod Cummins ISB QSB Other Engine Accessories

Connecting Rods

B Series engines use various connecting rods installed in different orientations, depending on where and when the engine was built. Generally, connecting rods should be installed in the same orientation as they were prior to removal. In special circumstances, this familiarization section may be referenced as a guideline.

The following information illustrates connecting rod styles and orientations for the Cummins® B Series 3.9 Liter (4 cylinder) and 5.9 Liter (6 cylinder) engines.

Each illustration shows the connecting rod and camshaft (1) as viewed from the front of the engine. The connecting rod capscrew holes help define the orientation of the connecting rod to the camshaft. One side of the rod has a through hole (2) and the other has a blind hole (3). The through hole is drilled through the rod. The blind hole is drilled into the rod and does not have an exit hole.
There are two possible orientations for the connecting rod:
Through hole (2) toward the camshaft
Blind hole (3) toward the camshaft.