Navistar International Corp. said its first-quarter loss declined from a year ago, and the company named Troy Clarke its new CEO, replacing Lewis Campbell, who is stepping down.

Truck producer Navistar International Corp. reported a loss of $153 million for its fiscal first quarter, attributing $112 million of the loss to costs of repairing faulty engines, including initial models of its 2010 technology engines.

Navistar International Corp. Thursday reported a loss for its fiscal first quarter, citing warranty costs and a brake manufacturer’s recall of a part that affected nearly 20,000 of its trucks.

The Environmental Protection Agency is investigating whether Navistar Inc. completed assembly of 7,600 heavy-duty 2009 model truck engines in 2010, thereby making them noncompliant with current emission regulations.

LISLE, Ill. — Navistar Inc. has submitted a 13-liter engine for federal certification that its sales chief says will meet U.S. emissions standards.

The Environmental Protection Agency said it would impose a penalty of about $1,900 per engine against Navistar Inc., beginning as soon as late February, if it produces heavy-duty truck engines that don’t comply with the agency’s 2010 emissions regulations.

Navistar Defense, a unit of Navistar International Corp., received an $880 million order from the U.S. government to upgrade military vehicles.

Investor Carl Icahn told CNBC that a potential merger between Navistar International Corp. and Oshkosh Corp. would “be a good merger” that would “create a lot of synergies.”

Investor Carl Icahn, who bought a 9.8% stake in Navistar International Corp. last month, will not seek representation on the company’s board and will vote for Navistar’s board nominees next year.