"I never was worried about EGR, but I can see how the prospect of it scared people," said James Pirie, one of the presenters on "Troubleshooting '02 Engines" at the Technology & Maintenance Council's Fall 2004 Meeting. Pirie, application engineer for engineering customer relations with International...
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"There is a unique application consisting of airport ground support vehicles that we have addressed," he said. "The problem stems from continuously operating under very low load conditions. This tends to foul the Diesel Oxidation Catalyst. To address this, International offers an option restricted to airport vehicles that have speed limiters to prevent on-highway operation."
"You can never break that paradigm," he said. "In other words you can never have that truck drive on the road. Most airport vehicles, number one, they don't have anti-lock brakes so they're not allowed on the road; number two, they're generally never licensed for road operation; number three, part of our allowance for the off-road trucks is that we put a road speed limit on there, of an artificially low road speed, so that even if they drove it on the road they wouldn't want to. So what we do is, when you meet all the criteria we'll allow a recalibration of the engine for off-road use."
Although Pirie had not heard complaints from customers about a fuel-mileage penalty with EGR engines, he said he expected some fleets to experience a loss.
"I wonder about the fuel economy issue, because I don't think there's any question operating costs have got to go up. You'd expect that," he said. "You cut the NOx emissions in half, regardless of how you do it, regardless of what your technology path is, you cut the NOx in half and you're really cutting into that."
Still, Pirie believes that smart fleet operators can minimize the impact of EGR fuel economy loss by training drivers to get the most out of the engine.
"Your driver is always 10 percent of your fuel consumption, so operating the engine in a way that minimizes the speed and increases the torque is probably still a good idea," he said. "The regions of best fuel consumption are still the regions where EGR is minimized."
DAVID McKENNA, MACK TRUCKS
Vince Lindley, manager of fleet services for Mack Trucks, filled in at TMC for David McKenna, product manager, marketing for Mack Engines, Transmissions & Axles. We spoke with McKenna to get an overview of the presentation, and he offered these insights into early Mack ASET '02 engine issues:
Concerning problems relating to technicians inadvertently loosening the Mass Flow Tube, McKenna explained "The tube itself is held in place at each end with a high temperature viton-lined silicone hose with constant tension clamps and a supporting bracket located in the middle. So the tube is removable."
"The two sensors (1-temperature; 2-mass flow) are in fact welded to the mass flow tube, so they are not separately serviceable. I think the confusion may come from the previous arrangement that had the temp sensor that was not welded and the mass flow that was. In a few instances some technicians tried to remove the mass sensor and broke the weld, damaging the sensor, rendering it inoperative."
A common concern with EGR engines is what effect the new technology may have on oil drain intervals, since EGR introduces higher levels of soot into the engine.
"For the vast majority of Mack ASET AC engines, 25,000 miles is the recommended drain interval," McKenna said. "On our vocation ASET AI, the drain intervals are set at 16,000 miles or 300 engine hours, whichever first occurs. High humidity and dew points can have an affect on some vocational engine applications. Higher humidity and high idle times with transient duty cycles can sometimes result in additional soot loading of the engine oil. With the use of fully automatic transmissions, in refuse operations the drain interval is reduced to 250 engine hours."
GREG HOLDERFIELD, VOLVO TRUCKS NORTH AMERICA
Lindley also filled in for the engine expert from Volvo, and we recently checked in with Greg Holderfield, director of technical support service, Volvo Trucks North America to get a recap of their presentation.
"Soot is a product of the combustion process, and higher horsepower engines will produce more soot, since they burn more fuel," Holderfield said. "Volvo has addressed this with recommended oil formulas that have superior soot handling capabilities."
"Some early EGR temperature sensors experienced cracking," he went on. "This has been addressed by a change in our assembly process. We also instituted a service program to replace any affected sensors in the field, and this program has been completed."