Born and raised in Spokane, Washington, Mengert played football at Gonzaga Prep, briefly attended Stanford University in the late 1940s, and served in the Washington Air National Guard and U.S. Air Force in the early 1950s. After three rounds, he was tied for fourth, two shots off the lead, and finished tied for ninth.
Mengert was runner-up in the 1952 U.S. Amateur to Jack Westland. Mengert turned professional in 1952 and worked mainly as a club pro while also playing on the PGA Tour. His best finish in a major came at the 1958 Masters Tournament.
Mengert was the first round leader at the U.S. Open in 1966 at the Olympic Club in San Francisco. He was tied for seventh after 54 holes, but a final round 81 resulted in a tie for 26th place. Mengert played several tournaments on the Senior PGA Tour in the 1980s, and was inducted into the Pacific Northwest Golf Association's Hall of Fame in 2001.
He was a head pro at clubs in New Jersey, St. Louis, and Sacramento. Mengert returned to the Northwest as the head pro at Tacoma Country Club in the 1960s then went to Oakland Hills in the suburbs north of Detroit, Michigan. 1946 International Jaycee Junior Golf Tournament.
1946 International Jaycee Junior Golf Tournament 1947 International Jaycee Junior Golf Tournament 1949 Washington State Amateur 1950 Mexican Amateur, Pacific Northwest Amateur, Washington State Amateur this list may be incomplete 1952 Northwest Open (as an amateur) 1957 New Jersey State Open 1958 New Jersey State Open 1960 New Jersey State Open, New Jersey PGA Championship, Metropolitan Open, Arizona Open 1963 Washington Open 1964 Washington Open 1965 Washington Open, Northern California PGA Championship 1966 Northwest Open 1968 Pacific Northwest PGA Championship 1969 Pacific Northwest PGA Championship 1971 Washington Open 1976 Michigan PGA Championship.
