After Jimmy St. John, an Atlanta native, earned his degree at Georgia Tech in 1959, his engineering career took him from one end of the South to the other, with an eight-year stint in Saudi Arabia during the 1990s.

When he retired, though, he chose to return to the city of his birth.

In his case, the term “retired” may be a misnomer. In fact, during his final 13 years in Atlanta, St. John kept a pace that bore a striking resemblance to full employment.

He was busiest at his church, Central Presbyterian in downtown Atlanta. There he was an elder, a faithful bass in its chancel choir and a chair of its global mission council. In line with that mission, he made three trips to Mexico’s Yucatan peninsula to oversee the construction of a community water system.

He turned his engineer’s eye to the church itself. He and a retired engineering firm executive, Roland Kinser, also of Atlanta, planned and supervised the installation of a new HVAC system for the church.

"The two of them saw to it the church got a 21st century system in a 19th century building, and that's no easy task," said Tom Leslie, former executive director of the Georgia Society of Professional Engineers and a church member. "As a bonus, they had solar panels installed on the church roof to provide constant hot water for the showers at our overnight homeless shelter."

The church’s senior pastor, the Rev. Gary Charles, said St. John never sought accolades for his deeds. “What mattered to Jimmy,” he said, “was overcoming the engineering challenges he encountered here. We continue to make incremental progress with the improvements in the church’s lighting system that he recommended.”

James Lee St. John, 75, died Monday at St. Joseph’s Hospital of complications following lung surgery he underwent a month ago. His memorial service is 2 p.m. today at Central Presbyterian Church. Cremation Society of Georgia is in charge of arrangements.

Though retired, St. John kept up with his profession, even conducting training classes in mechanical engineering. And he served on an editorial board overseeing publications of an alliance of engineering societies. “Jimmy was one of those rare engineers who could write,” Leslie said.

St. John took an interest in his Georgia Tech fraternity, serving as treasurer for the corporation that manages the Delta Tau Delta house.

“Jimmy did other things beyond the call of duty,” said Bob Gotsch of Roswell, the corporation’s president. “He collaborated with the city to create a new front patio for the house and totally rehabbed the fraternity’s leaking laundry room. In both cases, he did the work pro bono, and the results were excellent.”

His retirement wasn’t pure work. He joined a New Horizons band that performs regularly at churches and seniors residences. “He played tenor sax well enough to do solos,” said a fellow bandsman, J.C. Campbell of Cumming.

He took golf and photography seriously and traveled extensively with his wife of 12 years, Frances St. John. His first wife, Dolores St. John, died in 1998.

Also surviving are a son, Gregory St. John of Mableton; two stepsons, Ryan Parnell and Brendan Parnell, both of Atlanta; four grandchildren and six great-grandchildren.