GM’s $920M DMAX expansion in Brookville means closure (or new use) of Moraine plant

Original DMAX plant in Moraine will wind down, GM exec says

BROOKVILLE — The General Motors plant in Brookville will become the home of a $920 million investment in Duramax diesel engine production, quadrupling the size of the Campus Boulevard plant — and pointing the original engine plant in Moraine to eventual closure or a new use at an undetermined time, GM leaders said Friday.

“I think the original plant with DMAX has a good, long future with us,” said Mike Trevorrow, vice president, GM North America manufacturing. “We’re going to continue to build the engine there. And then as we start the other (new Brookville) factory up, it’s a good opportunity for them (Moraine DMAX workers) to come and be part of the history of heavy-duty trucks continuing.”

The Brookville plant covers about 250,000 square feet. About 1.1 million square feet will be added to that.

Asked when the Moraine workforce will be moved to Brookville, Trevorrow said, “We haven’t announced the timeline just yet. More to come with that.”

“We have the building to build, we have the tools to get in,” he added. “We have to get it up and running. We’re anxious to get going. But this is the first step.”

Then there will be the question of what GM will do with its Moraine plant off Dryden Road.

“There is always the opportunity to do something maybe there, but we haven’t announced anything yet,” Trevorrow said.

In the end, when consolidation is complete, the Brookville plant will be home to more than 800 workers, he added.

The automaker announced the expansion of its relatively new Brookville plant only a couple of years after it began operating off West Campus Boulevard.

Since 1998, DMAX has been a 60-40 joint venture of GM and Isuzu, with GM being the majority owner. The original DMAX plant in Moraine built more than 2 million heavy-duty engines in the two decades between 1999 and 2019.

Isuzu quietly ended its role in the joint venture last year in financial filings. DMAX is wholly owned by GM today.

In Moraine, the Dryden Road DMAX operation has been reliably productive, weathering recessions and the closure of an SUV assembly plant nearby in late 2008. For a long time, it was the Dayton area’s only GM plant.

DMAX in Moraine has usually had about 700 to 800 workers.

Strong demand for Chevrolet and GMC heavy and medium-duty pickups forced GM to find a way to make more Duramax diesel engines. In 2021, GM opened its Brookville DMAX plant, an operation initially meant to complement the work in Moraine.

When it was first announced in 2019, the $175 million Brookville plant was conceived as operating concurrently with the original DMAX plant, sending the Moraine plant machined engine components for assembly. Finished engines were sent to Flint, Mich. for assembly into trucks.

But GM continued to make moves in Brookville since 2019. The company purchased 53 acres of land in Brookville near its new plant.

And in time, as GM applied for economic incentives, local development officials acknowledged that a Brookville DMAX expansion would take jobs from Moraine.

Trevorrow made his remarks on the fate of the Moraine plant after the public portion of a plant celebration Friday. Other than references to a May 18 employee shooting at the Moraine plant, the original DMAX plant was not mentioned. GM’s press release on the investment did not mention the Moraine facility, either.

On May 18, an apparent dispute over a woman led one man to fatally shoot a coworker and then shoot himself in the head at the Moraine DMAX plant.

A third employee was also wounded in that shooting, possibly by a stray bullet as the man fired more than 12 rounds, Moraine police said.

The woman, who was also at the DMAX plant at the time, was not injured. Jeffrey James Allen III, 28, of Dayton was pronounced dead at the scene.

The Brookville investment is GM’s third in Ohio in the last 10 months, the company said. The automaker has also announced investments at its Toledo Propulsion Systems plant and another investment in its Defiance plant, totaling $1.7 billion.

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