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The crankshaft dynamic behavior of internal combustion engines are deeply influenced by its geometry and modal parameters. The modal density of a 6 cylinder crankshaft is high and, therefore, it is necessary the evaluation of its several modal parameters during the crankshaft development. This paper presents the calculation of modal parameters such as: natural frequencies, modal shapes and damping factors; of a 6 cylinder in line crankshaft from a Diesel engine. Two approaches are conducted, firstly, a numeric calculation based on finite element method to collect the free body shape modes and its natural frequencies, respectively. Successively, an experiment is realized by the use of an electro-dynamic shaker to excite the structure, and accelerometers to measure the acceleration in 21 interest points of crankshaft geometry. The 3 directions FRFs are presented for each point, and also, the estimation of modal parameters obtained by tools like CMIF, Stabilization Diagram and Polymax.