The trouble for U.S. Xpress Enterprises started when coolant began showing up in engine oil samples taken by the fleet, not long after it started receiving new 2002-compliant engines equipped with exhaust gas recirculation (EGR) technology. Yet a quick check of the affected vehicles found no leaks in the radiator or coolant hoses, says Brett Wacker, director of shop operations for the Chattanooga, TN-based carrier. That's when the company's technicians started looking at the EGR coolers, the only other place touched by the tractor's cooling system.

“We found cracks in the coolers and, in a way, that didn't surprise us,” he says, “because that's the point in the EGR process where you're going to see big temperature extremes: hot exhaust gas at 1,200 to even 1,600 deg. being cooled down to near 300 deg. before being recirculated back into the engine.”

The problem centered around the welded steel intake and exit valves on the coolers, which were incapable of expanding or contracting, U.S. Xpress found.

“As a result, we were experiencing a 90 to 95% fail rate on the EGR coolers back in 2002 and 2003,” Wacker says. “So we went back to the OEM with this information; as a result, they made design changes — using a ‘tube-and-shell’ design instead of a fixed weld — to allow the component to expand and contract due to the temperature fluctuations. That design change pretty much solved that issue.”

It also confirmed the value of the company's oil analysis program. “This situation reinforced the urgency to have an oil analysis program in place within our shop network,” notes Mike Morgan, U.S. Xpress' vice president-maintenance. “As a result, eight of ten times, if the oil tests positive for glycol [the key ingredient in engine coolant] and we don't see any leaks from the radiator or hoses, we know it's coming from an EGR cooler. It's helping us be far more proactive in terms of vehicle maintenance.”

Fleets know only too well how emissions control technology has increased new-truck sticker prices over the years as well as the cost to maintain them. Meeting the first round of emissions regulations in 2002, for example, added between $1,800 to $3,000 to the base cost of a Class 8 truck. For the second round in 2007, an extra $5,000 to $10,000 got tacked on followed by another $6,700 to $10,000 in 2010 to meet the final round mandated by the Environmental Protection Agency.

Higher maintenance costs followed sticker price increases as well in order to cover all the extra emissions-related components, including all the new computer controls and wiring harnesses. Engine maker Detroit Diesel Corp. (DDC) estimates that fleets should expect to fork over an average of $367 extra per year just for the 2007-related upgrades alone.


Also, since 2007, diesel-powered trucks come equipped with diesel particulate filters (DPFs) to remove particulate matter or “soot” from their exhaust streams. DPFs need to be cleaned when a truck reaches anywhere from 150,000 to 400,000 mi. on its odometer, or 3,000 to 4,500 in total engine operating hours. The cost to clean the DPFs has a broad price range, too, from $150 (cited by Volvo Trucks North America) to up between $300 and $500 per transaction (according to DDC).

Trucks also use ultra-low sulfur diesel (ULSD) fuel as part of the emissions reduction equation — fuel with a sulfur content of just 15 parts per million (ppm) compared to the 500-ppm level in on-road diesel prior to October 2006. According to the American Trucking Assns., that 15-ppm blend added as much as 13¢/gal. to the price of diesel.

Many fleets are finding that the training required for their technicians is pushing up the cost of maintenance in terms of emissions control systems.

“We've found our engine maintenance costs have gone up 50% between 2002 and today largely because of the training our technicians need on all the new technology, mainly in terms of diagnostics and troubleshooting processes,” says Rob Reich, vice president-maintenance for Schneider National.

“We really only made minor modifications to our preventive maintenance schedule to manage emissions-related components,” he stresses. “Even items such as our oil change intervals didn't change.”


OEMs note that making sure preventive maintenance schedules suffered only minor alterations became a major goal within their emissions control programs. “For example, during an ‘A’ service, exhaust plumbing to and from the DPF was added,” says David McKenna, director of powertrain sales & marketing for Mack Trucks. “For the ‘C’ service, 7th injector inspection and cleaning were added. We designed the exhaust aftertreatment system with routine preventive maintenance in mind.”

Schneider's Reich did note that there's been a greater “ripple effect” in some cases due to non-emissions component failures. “We've found that when a turbocharger fails, a lot of oil gets into the DPF and ruins it, forcing us to replace it,” he explains. “So down the road, we'd like to see development of a more robust DPF that can survive such situations.”

Fleets and OEMs are more divided on the subject of “information communication,” for lack of a better term, or more simply, just how much detail about the emissions control system should be shared with vehicle operators.

Matt Callaway, director of maintenance for U.S. Xpress, believes providing more information to drivers about emissions control technology has been the best tactic.

“We really went out of our way to help our drivers understand the DPF regeneration process such as when it was needed and how they needed to handle the vehicle during a ‘regen,’” he explains. “Proactively giving that information to our drivers so they knew what to expect and what to do when the ‘regen’ light on the dashboard came on really helped us and them to interpret and to solve issues better.”

McKenna, however, believes information overload actually turned out to be a bigger problem when it came to drivers dealing with the demands of emissions control systems.

“An initial ‘teething’ problem we experienced was communication between the vehicle systems and the operator,” he explains. “We provided too much information, such as letting the operator know that an active DPF regeneration event was pending with a bright amber lamp. Drivers would then toggle the DPF ‘Smart Switch’ to inhibit the regen.”

This ended up completely packing the DPF full of soot, and with the regen inhibited, it caused the trucks to lose power and eventually stop. “Later on, we then offered a ‘non-inhibit switch’ to eliminate the initial active indication, and overnight, 99.9% of the service calls went away.”

Then again, Jeff Sass, general marketing manager for Paccar Parts, thinks that it's really “audience dependent” when it comes to emissions control system information flow. While drivers might find too much information a hindrance, Sass says dealers and fleet managers need all they can get and more.

“We must have held 80 to 100 internal webcasts with dealers and their fleet customers about emissions control technology, webcasts lasting from 45 minutes to two hours,” he explains. “We walked them step-by-step through everything, including DPF cleaning. We ultimately found more information proved to be better, but the amount and detail of the information we needed to share really depended on our audience.”