Army ponders new diesel engine for Humvee trucks.

The Army is considering retro-fitting Humvee trucks with new diesel engines that, according to proponents, would lessen the workload for soldiers in the field.

Army officials have voiced frustration in recent months about maintenance nightmares experienced by units in Iraq, where Humvees get overloaded with armor, regularly break down and often require an engine change after only 1,000 to 2,000 miles of operation.

The frequency of the engine swaps has gotten the attention of the Army leadership. Soldiers complain that it takes eight hours and two people to remove and replace a Humvee engine.

Most Humvees come with 6.2 or 6.5-liter V-8 gasoline engines. But as more trucks are outfitted with bolt-on armor protection packages--which typically weigh 1,800 pounds--the engines, transmissions and suspensions take a beating, resulting in vehicle failures.

The newer Humvees are not a concern because they come off the production line with a beefed up suspension, and bigger engines and transmissions. But the older Humvees may be candidates for a new diesel engine. The Army's National Automotive Center is testing four Humvees equipped with a V-6 diesel made by Navistar International Truck and Engine Corporation. The engine originally was designed for the Ford F-150 pickup truck, but Ford recently backed out of the deal. Navistar nevertheless is expected to keep the engine manufacturing line alive for other customers, and begin production in October.

The Navistar engine likely will be challenged by other manufacturers in an upcoming Army procurement competition for a still-undetermined number of engines. Among the competitors will be a new 6.5 liter engine by AM General, the maker of the Humvee. The company invested its own fluids to develop the engine, specifically to help address the armor related weight problem, but sources speculated that this engine may be too expensive, unless AM General gets additional customers to spread the costs.

According to a military vehicle expert, a V-6 diesel would be a "wonderful thing for the Army," because it would provide higher fuel efficiency, as well as the additional horse-power and torque that the Humvees need to bear the excess weight.

The NAC, meanwhile, has contracted the services of Dennis Carlson, a recognized automotive engineer, who has come up with new techniques to maintain the Humvee and swap out the engine. If Carlson can work his magic, said one NAC official, the engine may be able to get changed in less than an hour.