UPDATE 2-Navistar lowers guidance, posts in-line loss

* Navistar posts loss of 16 cents a share

* Lowers full-year guidance

* Sees minimal pre-buy ahead of new clean-air rules

(Recasts, adds details on full-year forecast)

CHICAGO, Sept 9 (Reuters) - Navistar International Corp (NAV.N) cut its full-year earnings outlook on Wednesday, blaming continued weak demand for its trucks, buses and engines as well as "significantly higher" retiree benefit expenses.

Stating that "every part of our business, excluding sales to the U.S. military, has been affected by the global recession," the company reduced its profit forecast for the fiscal year ending Oct. 31 to a range of $2.55 to $2.85 a share, down from a previous range of $2.80 to $3.10 a share.

Truckmakers had hoped 2009 would be a good one for demand, thanks to tough U.S. clean air rules that take effect in 2010. The regulations, which require more efficient and more expensive engines, were expected to prompt fleet owners to stock up on cheaper trucks this year.

But the recession and credit crunch have effectively killed those hopes. In a filing with the U.S. Securities and Exchange Commission late Wednesday, Navistar admitted it only expected "nominal accelerated purchases" ahead of implementation of the new rules on Jan. 1.

The warnings came as Navistar reported a quarterly loss that was in-line with expectations.

The Warrenville, Illinois-based company said it lost $12 million, or 16 cents a share, in the three-month period ended July 31; during the comparable quarter last year, it posted a profit of $331 million, or $4.47 a share.

The results for the most recent quarter included a one-time gain of 33 cents a share related to its purchase earlier this year of some of the assets of bankrupt RV maker Monaco Coach Corp.

Analysts, on average, expected Navistar to report a loss, before the extraordinary item, of 49 cents a share, according to Reuters Estimates.

At $2.51 billion, total sales and revenue fell short of the $2.67 billion analysts had expected, according to Reuters Estimates. The drop in sales of the company's International brand trucks and engines was especially sharp, down 37 percent to $2.43 billion, while revenue from its finance operations slipped just 2.6 percent to $73 million.

(Reporting by James B. Kelleher; Editing by Phil Berlowitz)