With nearly half a million miles on four Mack tractors equipped with cooled-EGR diesel engines, regional carrier D.M. Bowman reports that initial fuel economy numbers were 4% below non-EGR engines, but seem to be improving as the engines accumulate more miles. Drivers' response has been uniformly positive and “they see (the cooled-EGR engines) as an enhancement,” says Sam Kennedy, Bowman's chief maintenance officer.
The fleet is running Mack Vision models with 70-in. high-rise sleepers and 427-hp. versions of Mack's on-highway ASET engines certified as meeting the federal Oct. '02 emissions levels.
Oil analysis has turned up “no significant differences” from earlier non-EGR engines in the fleet, according to Kennedy. The fleet has, however, moved from its extended 40,000-mi. drain intervals to Mack's recommended 25,000-mi. interval for the new engines. The only reliability issue was a turbocharger failure that was blamed on a compressor-wheel design that has since been replaced. The new engines have required no other maintenance or coolant changes, “and I'm optimistic we'll see the same durability,” Kennedy says.
Mack began production of the on-highway version of the ASET engine just prior to the October 2002 deadline and reported delivery of 453 trucks with that engine by early April. Mack also developed a second ASET diesel with an internal EGR system that does not use an exhaust-gas cooler or variable geometry turbocharger for off-highway and vocational-truck applications. With production of that engine starting last June, the company said it had delivered 3,343 trucks with the off-road version by early April.
