General Motors builds Duramax diesel engines at two U.S. plants

Duramax is a diesel engine line owned and manufactured by General Motors (GM). GM designs the engines and builds them at facilities in the United States, primarily at the Duramax engine plant in Moraine, Ohio, and historically at a plant in Tonawanda, New York. The engines power GM's heavy-duty pickup trucks — mainly Chevrolet Silverado and GMC Sierra models — and are sold to other manufacturers as well.

GM did not invent the Duramax line from scratch. The original Duramax engine was co-developed with Isuzu in the late 1990s, and Isuzu supplied early versions. However, GM has owned the Duramax brand since 2005 and now designs and manufactures all current Duramax engines in-house.

Key Takeaways

  • General Motors owns and builds Duramax diesel engines at its Moraine, Ohio facility and previously at Tonawanda, New York.
  • Duramax engines power Chevrolet Silverado and GMC Sierra heavy-duty trucks, as well as some commercial and industrial equipment.
  • GM co-developed the original Duramax with Isuzu in the late 1990s but has owned and manufactured the line independently since 2005.
  • The Moraine plant is a dedicated Duramax facility that also produces related diesel components and transmissions.

The Moraine, Ohio manufacturing plant

The Moraine Engine Plant, located near Dayton, Ohio, is GM's primary Duramax production facility. This plant manufactures the current generation of Duramax engines and has been the center of GM's diesel engine production for decades. The facility employs hundreds of workers and operates multiple production lines to meet demand from GM's truck division and external customers.

Moraine is not solely a Duramax plant — it also produces other diesel engines and related components. The plant has undergone modernization over the years to support newer engine designs and emissions standards. GM has invested in equipment upgrades to increase production capacity and improve manufacturing efficiency at this location.

Historical production and the Isuzu partnership

The Duramax story began in the late 1990s when GM and Isuzu formed a joint venture to develop a new diesel engine for light-duty trucks. Isuzu, a Japanese manufacturer with decades of diesel informed, contributed engineering and initially supplied engines to GM. The first Duramax engines appeared in Chevrolet Silverado trucks in 2001.

This partnership lasted until 2005, when GM bought out Isuzu's stake and took full ownership of the Duramax brand and technology. From that point forward, GM has designed and manufactured all Duramax engines independently. Isuzu no longer supplies engines to GM, though the original Duramax architecture still reflects the joint development work from the early 2000s.

Current Duramax engine generations

GM currently produces two main Duramax diesel engines: the 6.6-liter LM2 and the 3.0-liter LZ0. The 6.6-liter is the traditional heavy-duty option found in Silverado and Sierra trucks, while the 3.0-liter is a newer, smaller diesel introduced to meet fuel economy standards and appeal to buyers who want diesel efficiency without the size of the traditional engine.

Both engines are built at the Moraine facility and meet current U.S. emissions regulations. GM continues to update Duramax technology to improve fuel economy, reduce emissions, and increase power output. The engines are paired with GM's Allison transmission in many applications, creating a complete powertrain package.

Other manufacturers using Duramax engines

Duramax engines are not exclusive to Chevrolet and GMC trucks. GM sells Duramax engines to other manufacturers for use in medium-duty commercial trucks, buses, and industrial equipment. This business segment provides GM with additional revenue beyond its own truck sales and helps keep the Moraine plant operating at higher capacity.

The availability of Duramax engines to external customers has made them a recognized option in the commercial vehicle market. Some vocational truck builders and specialty manufacturers choose Duramax engines for their reliability and fuel economy, even though they are not affiliated with GM.

Quality control and testing at the plant

Engines built at Moraine undergo multiple quality checks before they leave the facility. GM uses automated testing systems to verify engine performance, emissions compliance, and durability. Each engine is run and tested to may support it meets specifications before installation in a truck or shipment to a customer.

The plant also maintains engineering and technical support teams that monitor production data and investigate any issues that arise in the field. If a pattern of problems emerges, the plant can adjust manufacturing processes or design specifications to prevent recurrence.

Frequently Asked Questions

Is Duramax made in the United States?

Yes. Duramax engines are manufactured at GM's Moraine, Ohio plant. All current production Duramax engines are built in the U.S., not imported or outsourced to other countries.

Does Isuzu still make Duramax engines?

No. Isuzu co-developed the original Duramax engine with GM but stopped supplying engines in 2005 when GM bought out the partnership. All Duramax engines since then have been designed and built by GM.

Can I buy a Duramax engine separately from a truck?

Yes, but not directly from GM as a consumer product. GM sells Duramax engines to commercial truck builders, equipment manufacturers, and industrial customers. Individual buyers typically purchase Duramax engines as part of a complete vehicle from Chevrolet, GMC, or an authorized dealer.

What happened to the Tonawanda plant?

GM's Tonawanda, New York facility previously produced Duramax engines but is no longer the primary production site. Moraine, Ohio is now the main Duramax manufacturing location. Tonawanda has been repurposed for other GM engine production or has reduced operations.

How long has GM owned Duramax?

GM has owned Duramax outright since 2005, when it purchased Isuzu's stake in the joint venture. The brand was originally co-developed starting in the late 1990s, so GM's involvement spans over two decades, but full ownership dates to 2005.