Abstract: An internal combustion engine comprises a crankshaft having at least one rod journal and at least one main journal, a cylinder block rotatably supporting the crankshaft, at least one coupling member rotatably coupled to the crankshaft. The at least one coupling member has an annular, substantially cylindrical inner wall defining a crank bore circumscribing one of the main journals and/or one of the rod journals of the crankshaft. Moreover, the inner wall of the crank bore has at least one substantially annular recessed portion formed therein which is axially spaced from opposite ends of the inner wall. The internal combustion engine further comprises a vibration dampener assembly disposed in the recessed portions formed in the coupling member thereby substantially dampening and isolating transmission of vibrations between the connecting rods and the crankshaft and between the connecting rod and the cylinder block.