A New Bedford city mechanic died while trying to fix an excavator Friday, police said. Carlos Tabares, 55, was repairing a Bobcat excavator at the New Bedford Water Division, police Lieutenant John Chaves said. Tabares was facing the machine’s cab when the arm released, crushing him against it. Tabares was taken to St. Luke’s Hospital, where he was pronounced dead at 12:10 p.m., Chaves said. Mayor Jon Mitchell said Tabares had worked for the city nine years and was “well liked by his co-workers.” The accident is under investigation.