McIlhargey was born on March 7, 1952 in Edmonton, Alberta. McIlhargey's playing career spanned eight years on defence, beginning when he turned pro with the Philadelphia Flyers in 1974. He became a Canuck on January 20, 1977 when he was traded to Vancouver with Larry Goodenough in exchange for Bob Dailey. He appeared in 167 games for the Canucks (1977–80) before being dealt back to Philadelphia for cash on January 2, 1980. He finished his NHL career for the Hartford Whalers after he was traded there with Norm Barnes on November 21, 1980 for Hartford's second round choice in the 1982 Entry Draft. He played in 393 career NHL games recording 11 goals, 36 assists and 1102 penalty minutes. He retired following the 1981–82 season.