SHEFFIELD — Jim and Dorene Boltrom were a generous and busy pair. A couple of “lovebirds” who stuck close together for more than two decades after marrying on a Christmas Eve.

It was a bond that translated to kindness, said Dorene’s sister, Janine Kifer.

“They were a loving couple,” she said in a phone interview Thursday. “They would help anybody and they both gave of themselves.

Family and friends of the couple are heartbroken over the deaths of James “Jim” Boltrom, 75, and Dorene (nee Crocco) Boltrom, 66, in an early morning fire Wednesday at their log home in Ashley Falls.

Investigators have not yet determined the cause of the blaze on Hewins Street, but Kifer said investigators believe it likely began in the fireplace or the furnace.

Neighbors reported the fire just before 6 a.m., and when firefighters arrived minutes later, the house was engulfed in flames.

Two of the couple’s cats perished; the others could not be found, Kifer said.

Jim was a lover of puns, occasional pranks and doughnuts from Dunkin’. He was also remembered as a wise giver of advice, and for his scavenging for automotive parts for his shop, Commonwealth Automotive Restoration, which was right next door.

He was widely respected as a mechanical genius with a passion for authenticity in rebuilding vintage vehicles, particularly military jeeps — a man who knew where to find unopened tubes of grease from the 1940s and insisted on hand-filing axle knuckles, said friend Donald Campbell, who, in a sweat equity arrangement, spent 17 years restoring his 1965 Tuxedo Park CJ-5A Jeep with Jim.

Jim once taught Kifer to “build a speedometer from scratch.”

“He made a plow truck from scratch, he refinished a fire truck,” she said. “He showed me how to take apart my lawn mower.”

The shop was full of multiple projects and parts. But it was owned by a man who was in it for love rather than completion, and always in consultation with a spirited constellation of vintage restoration enthusiasts.

“He said the journey was much more important than the end product,” Campbell said.

Dorene was right there with him. She knew how to do that hand filing, and would show others how. She fielded business calls for Jim while his head was deep in a project and would explain her husband’s work process to customers.

“She kind of buffered things a little bit,” Campbell said. “She was just as knowledgeable.”

The two had lunch together every day after Jim would walk back to the house.

“They did everything together,” Kifer said. “She’d be gone for a night and he’d miss her. They never got to have kids, but they had each other.”

Kifer said that her sister, who used to work at a school in Connecticut for those with special needs, had moved with Jim to Ashley Falls in 2000 to take care of Jim’s parents and an uncle.

“They all loved each other,” she said of the extended family. “She was a caregiver.”

Dorene, originally from Waterbury, Conn., loved bingo, dancing and cats — she was a collector of strays, and the couple loved animals so much they let them graze on their compost pile near the fence.

“Jim called it ‘the fence line diner,’” Kifer said.

Jim also built the stone wall around the house.

“He was very deliberate, fastidious,” Campbell said, noting that his mechanical drawings were always “pretty darn close to what we were trying to build or fix.”

Jim’s father, John Boltrom, was a lifelong mechanic and machinist who supervised a factory that made parts for naval warships during World War II and who eventually moved to Ashley Falls to help Jim with his work.

Campbell said that you couldn’t rush Jim.

“It was all about the authenticity and being period-correct,” he said.

He said that Jim was always kind, but when someone walked into the shop with a get-it-done-quick attitude, “Jim would just turn around and say, ‘Good luck.’ He worked at his own pace.”

In a 1990 profile about Jim’s work in The Eagle, Bernard Drew wrote: “He reuses as many original parts as possible — even it means, in one case, 2,500 blasts with a torch to remove dents from a hood.”

At that time, Boltrom was also rebuilding a 1954 Porsche Spyder, known for being the model James Dean was driving when he was killed.

His work methods, Jim told Drew, are so meticulous that they “drive you a little crazy.”

Campbell recalls the nearly two decades with Jim, learning how to weld and sandblast, traveling around for parts, and restoring his jeep.

“My wife kept saying, ‘When is this thing going to be done?’ and Jim would say, ‘It’s done when I tell you it’s done.’”

Heather Bellow can be reached at hbellow@berkshireeagle.com or 413-329-6871. On Twitter

@BE_hbellow.