TMC issues scorecard on 2007 diesel engines
Mar 1, 2008 12:00 PM
The Lead-off technical session of TMC's annual meeting was a panel discussion by several large fleets of their experiences with 2007-emission compliant heavy duty diesel engines, compared to 2002 and 2004 emissions engines. Overall, these fleets found the engines to be more expensive to purchase, more costly to operate, and had considerably more downtime.
On the positive side, the fleets said the new 2007 diesels provide performance improvements.
“The trucks are hot rods and the drivers really want to drive them,” said Dan Umphress, managing director-maintenance solutions, FedEx Freight. “Drivers have enjoyed responsiveness of newer engines,” added Tom Newby, director-field maintenance, Old Dominion Freight Line.
The two were on the panel along with Steve Duley, vice president-purchasing equipment, Schneider National.
All three reported that their fleets had a steady improvement in engine performance and fuel economy through each emission standard. However, when engines are measured against pre-emission diesels, the 2002, 2004, and 2007 engines all cost sequentially more through each model year, particularly in terms of purchase price, maintenance, decreased fuel economy, and downtime.
Umphress, Newby, and Duley each concurred that along with training for service technicians on the 2007 emissions engines, education of drivers is required for their understanding of particulate trap operation and regeneration.
FedEx Freight
From FedEx Freight's experience with 2002 and 2004 emissions engines through early 2007, Umphress reported a $4,000 increase in vehicle acquisition cost. Fuel economy dropped about 3 percent. There was no change in maintenance schedules, but the fleet experienced high failures of new emissions components — turbochargers, EGR (exhaust gas recirculation) valves, coolers, sensors, etc.
The carrier's standard power unit is a 4×2 non-sleeper tractor that pulls two 28-foot trailers, grossing around 66,000 pounds.
With the 2007 emission compliant engines, there was a $7,000 increase in acquisition cost. Fuel economy remained at about 3 percent below pre-2002 and 2004 emissions engines.
Umphress said the emissions components on the 2007 engines have been much more reliable than 2002 and 2004 emissions engines. Nevertheless, maintenance schedule changes were required for the 2007 engine's coalescent crankcase filter and diesel particulate trap.
Drivers need training on the new 2007 engines, he said, especially with regard to the new exhaust emission systems' warning lamps and dash controls that vary by truck manufacturer.
Old Dominion Freight Line
Old Dominion Freight Line is running 7.2-liter EGR and 13-liter and 15-liter CGR (cooled gas recirculation) engines. Because of the extra weight of the engines, placement of the fifthwheel was moved back for weight distribution purposes and the gear ratios were changed.
