LISLE – Navistar, the truck and engine maker in the midst of a turnaround, on Thursday promoted its president and chief operating officer, Troy Clarke, to CEO.

The Lisle company also on Thursday posted a loss for its November-January quarter as revenue fell 12 percent. Demand fell across the industry and Navistar also lost market share because of its transition to a new kind of emissions technology. But the interim CEO, Lewis Campbell, sounded an optimistic note Thursday. He said the company is starting on the road back to profitability and new engine programs are progressing on schedule. He predicted that Navistar will begin to pick up market share in the second half of the year as it launches the new engine models.

As sales slumped last year, Navistar launched a cost-cutting drive and said it would explore putting some of its businesses up for sale. It also averted off a proxy war with activist investors, including Carl Icahn, by adding board members aligned with them.