In 1984–85, Dineen spent time with the Islanders American Hockey League (AHL) affiliate, the Springfield Indians. In 25 games with Springfield, Dineen had a goal and nine points. He spent a majority of the 1984–85 season with the Islanders, playing in 48 games, scoring a goal and 13 points, as well as earning 89 penalty minutes. In 10 playoff games with New York, Dineen had no points and 26 penalty minutes. Dineen again split the 1985–86 season between Springfield and New York. In 11 games with the Indians, Dineen had two goals and five points. In 57 games with the Islanders in 1985–86, Dineen had a goal and nine points in 57 games. In three playoff games, he was held with no points.