Dineen, a native of Montreal, played high school hockey at Loyola High school. He played junior ice hockey in the Toronto area from 1960–1964. He was a member of the 1961 Memorial Cup-winning Toronto St. Michael's Majors team and the 1964 Memorial Cup-winning Toronto Marlboros team. That year, he joined the new Canadian national ice hockey team. In all, he played in five seasons with the national team, along with one season with the University of British Columbia. Dineen played for Canada in the 1964 and 1968 Olympic Games, and the 1965–1967 World Championships. The team won the bronze medal in the 1966 and 1967 World Championships and a bronze in the 1968 Olympics. Dineen became a professional in 1968, signing with the Minnesota North Stars organization. In the 1968–69 season, Dineen made his only appearance in the NHL, with four games. He played the bulk of the season with their Memphis farm team. He played two more seasons of professional hockey before retiring after the Springfield Kings won the Calder Cup championship of the American Hockey League in 1970-71. The following season he would move into coaching with the Kings, and would go on to coach and GM the Kings and Springfield Indians for several years. In 1972 he helped form the Springfield Olympics of the New England Junior Hockey League where he coached the 'Pics to several Wallace Cups as league champions, and remained part of the franchise until his death. He helped develop several players who would go on to division 1 and 2 college hockey programs. He also had a few of his former players go on to successful careers in the NHL, including Bill Guerin. Dean Lombardi, current President and General Manager of the Los Angeles Kings of the National Hockey League, also played for Dineen in the mid-late 1970s. Dineen made West Springfield, Massachusetts his home with his wife and daughter for well over 30 years. His keen hockey intellect and coaching abilities made him a magnet for upper echelon junior players from New England, primarily Western Massachusetts/Northern Connecticut, who aspired to play college and professional hockey. He was inducted to the MassachusettsHockey Hall of Fame, in addition to being honored with the USA Hockey Presidents Award and the American Hockey Coaches Association's "Snooks Kelley Award".
