ORLANDO, Fla. – The additional cost of running emissions-compliant diesel engines made since 2002 amounts to between 6.7-8.2 cents per mile, according to Steve Duley, vice president of purchasing at truckload giant Schneider National in Wisconsin. That includes the incremental acquisition cost of engines meeting the 2002/04 and 2007 EPA standards, additional fuel expenses arising from efficiency losses, and the extra maintenance required on emissions hardware.
“I don’t think we’re ever going to get back to pre-2004 costs,” Duley said, “but we’re getting better.”
Speaking at last week’s annual meeting of the Technology and Maintenance Council of the American Trucking Associations, Duley was joined in a technical panel session by Dan Umphress of FedEx Freight and Tom Newby of Old Dominion Freight Lines. The session aimed to offer a “scorecard” on 2007 diesels so far, but there are so few in the field – only Cummins has delivered engines in serious quantities — that relatively little experience has been accumulated.
The three men, who operate some 24,000 highway tractors between them, agreed on several points: that engine-related costs have risen dramatically since 2002; that most engines have become more reliable and gradually more fuel-efficient than the first batch produced in 2002 or 2004, though they’re still a fair way from pre-2002 form; that regeneration of the diesel particulate filter (DPF) on ’07 engines is a continuing issue; and that drivers uniformly enjoy the improved responsiveness of trucks powered by these engines.
Umphress, managing director, maintenance solutions at FedEx Freight, called post-2002 trucks “hot rods”, adding that ’07 motors are drawing the same positive response from drivers. With 2002 engines his fleet first saw a 16 percent drop in fuel economy, but that was ultimately proven to be a matter of programming, and subsequent calibration updates improved the loss to just 3 percent. At the outset there was also a high failure rate with turbochargers and EGR valves, but that too improved.
On 2007 engines, Umphress said, emissions components have been “much more reliable” and fuel economy has been “a little better” than later engines with the ’02/04 spec. Typically, FedEx Freight engines automatically do one active regeneration of the DPF per night during highway work.
As to the cleaning of DPFs, he said the interval is not yet cast in stone but they’re “thinking about 200,000 miles.”
His advice? Work with engine makers to match engine mapping to your duty cycles.
Tom Newby, director of field maintenance at Old Dominion, agreed with that point, saying that an unexpected benefit of all this emissions turmoil is a new relationship with his engine supplier.
“We got that personalized communication back,” he said.
His experience with ’07 engines is relatively limited as his engine-maker of choice was late in getting the new product into the field, and none of these engines is fully broken in. But so far, Newby said, reliability has been about the same as the earlier EPA breed while fuel economy is slightly worse – 6.7-6.9 mpg for pre-07 13-liter engines vs. 6.4-6.8 mpg for the newer models. His 15-liter engines have fared slightly worse – 6.3-6.5 for the older engines vs. 5.9-6.1 for the current crop. The fleet’s governed road speed is 68 mph (109 km/h).
Significantly, Newby has not embraced the CJ-4 oils recommended by all engine suppliers for use with ’07 engines running on ultra-low-sulfur fuel. Old Dominion is still using the earlier CI-4 spec, though he’s testing the newer lube with a small group of trucks in the 5,000-tractor fleet.
The same is true at Schneider National, where Steve Duley is also testing CJ-4 oil but still using CI-4 even in ’07 motors. That may demand earlier DPF cleaning but so far no interval has been determined. So far, Schneider’s current-model engines are delivering about 2 percent lower fuel economy than the 2005 models in the fleet.
The main issue there is the new aftertreatment system, he said, which has seen ’07-engine trucks in the shop far more often, usually with DPF regeneration issues. Downtime has increased 20 percent, Duley said. There have been “far too many” manual regens by his drivers, indicating the need for further training – drivers have had only one hour of training on the new engines, while Schneider mechanics have had 40 hours of instruction.
Despite the problems with ’07 motors, Duley was quick to say that the fleet has had “very excellent support” from their engine supplier.
Have your say
We won't publish or share your data