The number of 2010 EPA emission-compliant heavy duty on-highway diesel engines in use has been gradually increasing. “The slower uptake of the 2010 and now 2011 engines has been more a function of lack of confidence in the economy than lack of confidence in the technology,” says Allen Schaeffer, executive director of the Diesel Technology Forum, an organization dedicated to raising awareness about the economic importance of diesel engines.
“The March freight tonnage index is up over 6 percent according to the American Trucking Associations, and recently, ACT research reported that Class 8 truck orders are now up more than 25,000 units for five consecutive months,” he says. “That would put us on a yearly pace of well over 200,000 units - a very strong sign of recovery and a confidence in the technology.”
With the economy on the uptick and fuel prices at $4 per gallon-plus, fuel efficiency is more important than ever before. Truck orders are up in large part due to the benefits of the new engine technology in saving fuel, says Schaeffer. “Everyone is pretty consistently saying they are getting 5 percent gain in fuel economy.”
SATISFIED USERS
In general, customer acceptance and satisfaction of the 2010 EPA engines is quite high. Truck owners and users have been “very satisfied,” and in many cases the results have exceeded their expectations for performance and power, and they have experienced fuel economy surpassing 2007 engine levels.
“We know the diesel engine still has a few tricks left up its sleeve in getting more efficiency out, and that is expected to be in round one of the final greenhouse gas emissions rule,” the Diesel Technology Forum’s Schaeffer says. “The later aspects of the rule will likely push more into vehicle integration and vehicle issues than engine issues.”
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DRIVING DIFFERENCES
For drivers, “it is a matter of awareness and education” with the 2010 EPA engines, says Kurt Freitag, director of aftermarket for Paccar, which manufactures Kenworth and Peterbilt trucks. These engines are “significantly different in how they run compared to previous engines.” Because the engines are quieter, the driver feels different sensations - less vibrations, no turbo noise, no rumbling, etc.
A driver that is used to hearing turbo noise or feeling the way a vehicle vibrates as an indication to shift won’t have that with the new engines, he says.
ENGINE SALES
From January 1, 2010, through end of March 2011, Cummins has built and shipped more 89,100 EPA 2010 engines, says the company’s Christy Nycz, manager of on-highway communications. More than 25,000 of that volume include ISX15 and ISX11.9 engines.
Paccar began installing its 2010 emissions-compliant MX diesel engines in Kenworth and Peterbilt trucks for the U.S and Canada last June, says Paccar’s Freitag. “Currently we have thousands in service and demand is up.”
“Since the start of the commercial launch in September 2009 of our fully certified EPA 2010 Mack ClearTech engines, demand has been strong, even in light of the mountain of stockpiled competitor pre-2010 engines,” David McKenna, Mack Trucks’ director of powertrain sales and marketing, says.
Ed Saxman, product manager - powertrain, for Volvo Trucks North America, says: “Since we started filling customer orders for actual production units in the fall of 2009, more than 1,000 customers across all market segments in the U.S. and Canada have purchased trucks with Volvo’s EPA 2010 solution. Demand continues to grow and we continue to see a very strong re-order rate.”
“Detroit Diesel Corporation has produced or sold approximately 65,000 EPA 2010 engines since January 1, 2010, and has delivered more than 30,000 of them to customers,” says Brad Williamson, manager of engine and component marketing for Daimler Trucks North America. Detroit Diesel is an affiliate of Daimler Trucks.
Tim Shick, director of marketing, for the Navistar Engine Group, says about 40,000 Advanced EGR 2010 engines have been produced, including 12,000 MaxxForce 13 and 18,000 MaxxForce DT engines, with the balance lower volume engines.
MAINTENANCE ISSUES
None of the manufacturers have found any significant engine issues or problems. A few reported some minor controls and calibration issues with the very earliest of engine deliveries but these were quickly resolved.
“The only real issue we’ve experienced is the collection of empirical data on engine performance because we’ve had so few problems,” says Mack Trucks’ McKenna. “We actually have to ask our dealers and customers to upload logged vehicle data for analysis in support of, and validation of, our performance predictions.”
“Measured by reported faults, this has been Volvo Trucks’ most successful engine introduction,” notes Saxman of Volvo Trucks. “Much of our success can be attributed to our No Regen strategy, which uses only NOx (nitrogen oxide) for passive regeneration of soot from the diesel particulate filter. Because we’re not using fuel to regenerate soot, temperatures are much lower.
“Our most ‘senior’ EPA ‘10 engine now has well over 300,000 miles in all sorts of conditions and we’ve had no problems.”
DEF MATTERS
EGR (exhaust gas recirculation) is an emissions reduction technique that works by re-circulating a portion of an engine’s exhaust back to the engine cylinders and burning off excess pollutants. Navistar is the only engine manufacturer to use EGR to meet 2010 diesel engine emission regulations.
The other manufacturers use selective catalytic reduction (SCR). SCR uses a urea-based diesel exhaust fluid (DEF). Small quantities of DEF are injected into the exhaust upstream of a catalyst, where it vaporizes and decomposes to form ammonia and carbon dioxide.
“We’ve been pleasantly surprised about the lack of issues relative to the DEF systems,” says Schaeffer of the Diesel Technology Forum. “As far as we know, there are not any supply issues with DEF or its availability in the first full year of use, and that’s pretty impressive going from none anywhere to adequate supply in about three years.”
Problems with diesel exhaust fluid systems have been a non-issue since early 2010, adds Williamson of Daimler Trucks North America. The industry as a whole stepped up and answered the call for a DEF infrastructure. “There are over 3,500 locations across North America where drivers and fleets can purchase diesel exhaust fluid.”
Adds McKenna of Mack Trucks: “The introduction of DEF has gone smoothly and is widely available at affordable prices.”
DPF SYSTEMS
All of the engine manufacturers say they have been very pleased with performance of their aftertreament systems and have not had any noteworthy issues. Each stressed the importance of having the system’s diesel particulate filter (DPF) serviced at regular intervals. “A dirty DPF still ‘breathes,’” says Saxman of Volvo Trucks, “but it’s more effective if kept clean.”
Both EGR and SCR emissions technologies utilize DPF technology to decrease particulate matter (soot) emissions.
Paccar’s Freitag says many of the issues with aftertreatment systems can be traced to drivers not understanding the DPF status lights for regeneration activities.
DPF TECHNOLOGY
Basically, DPF technology works by employing a honeycomb ceramic structure with a series of alternate channels plugged at opposite ends. The diesel exhaust gas is forced through the open end of each channel.
The plug forces the soot particles against the porous channel cell walls to burn off there and allow only gases like steam and carbon dioxide (CO2) to pass through to the neighboring exit channel.
Highway driving and high engine load results in lower accumulations of particulate matter (PM) and high exhaust temperatures. A lot of idling and low speed/low engine load creates more PM, causing soot to build up in the DPF. Successful thermal regeneration clears the DPF of all the soot.
There are two types of thermal regeneration: passive and active. Passive regeneration happens automatically during vehicle operation when the heat of the exhaust burns off the soot.
Active regeneration becomes necessary when the temperature is too low to completely burn off the soot. The process is initiated by injecting fuel into the exhaust automatically, with no driver interaction needed.
However, if soot continues to accumulate in the DPF, a parked regeneration is required. The driver is alerted to this through the DPF indicator lamps on the instrument panel. He must park the vehicle and initiate the regeneration process by pushing a button on the dash or holding the accelerator at a high idle rpm for up to 30 minutes.
LIFE EXTENTION
Although the DPF is designed for long life, to ensure that an optimum level of performance is maintained, the filter must be cleaned at regular intervals. This is necessary as small amounts of inert debris, mainly accumulated mineral and metal particulate from lubricating oil and engine wear, build up in the filter substrate. This inert, unburnable material is known collectively as ash.
Ash builds up and occupies space in the cells intended for soot. However, unlike soot, ash does not burn off. It must be physically removed from the DPF.
Typically, most engine OEMs recommend this be done between approximately 200,000 to 250,000 miles for less severe service applications, such as Class 8 linehaul operations.
FILTER ISSUES
Some fleets think that by ignoring ash buildup in their DPF they can avoid another operating expense. Besides, if the DPF fails under warranty it is covered.
Other fleets have discovered that by allowing the DPF to fill up with ash it will eventually crack and rot out to the point that the ceramic material breaks up, crumbles and blows out the exhaust stack. Provided the truck has not been forced to the side of the road with backpressure warnings, the ceramic core can partially or totally disappear.
This sudden loss of backpressure will result in a slight improvement in engine performance and mileage.
One problem comes when the truck is resold and a new replacement DPF must be installed costing several thousand dollars.
Since the primary function of a DPF is to eliminate soot from diesel exhaust prior to escaping to the atmosphere, the DPF is vital to helping prevent serious air pollution, says Drew Taylor, national sales manager for FSX Equipment, a company that provides filter cleaning systems and services for cleaning diesel particulate filters.
He says a good rule of thumb is: If you observe soot (black) in the exhaust stack/pipe or observe heavy black smoke coming from a truck’s stacks, this is a sure sign the DPF is not working and harmful pollutants are being emitted into the atmosphere.
COMMON MYTH
Since 2007, to meet EPA heavy duty diesel engine emission requirements, vehicles now come standard with aftertreatment system warning lights and indicator symbols. These alert the operator to actions being taken or to actions that need to be taken.
“One of the most common DPF myths circulating is that the DPF status light indicates when the DPF needs to be cleaned of ash,” says Taylor. “That is false. This light keeps the driver informed about the active regeneration system as it periodically clears out soot buildup to relieve backpressure created by soot.
“By the time the DPF status light shows signs of ash buildup in a DPF, the condition is so far advanced that substrate cracking and other damage are well under way,” he points out. “The only way the driver can see this is by noticing the regenerations are occurring one after another as the sensors detect DPF backpressure that does not respond to thermal regeneration.”
This is why ash removal must be done proactively as a scheduled maintenance item, stresses Taylor. The best DPF rule of thumb: Take it off and clean it sooner than later.
“If you leave ash in the DPF too long it becomes like a cancer that grows in the filter over time,” he says. “If left in place, the ash becomes hardened, making removal even more difficult. The solution is to get the ash out before it has the time to solidify.
“Because the ash is cooler than the surrounding material, it causes cracking of the brittle ceramic. Once the cracking starts, it is irreversible damage that will continue to worsen and eventually destroy the filter.”
SNIFF TEST
In the near future, opacity testing - commonly referred to as the sniff test - will become more commonplace to detect emissions cheaters.
In an effort to control excessive smoke emissions, California already requires annual smoke inspections for heavy duty vehicles, notes Taylor of FSX Equipment. This is through the California Air Resource Board’s Periodic Smoke Inspection Program (PSIP).
The PSIP requires diesel and bus fleet owners to conduct annual smoke opacity inspections of their vehicles, and repair those with excessive smoke emissions to ensure compliance.
A fleet owner that neglects to perform the annual smoke opacity inspection is subject to a penalty of $500 per vehicle, per year. The penalties for excessive smoke range from a fix-it ticket to a $1,800 citation, and the California Highway Patrol can take the vehicle out of service.
Basically, a smoke test is a simple, brief test performed on a vehicle when it is standing still and in neutral. The engine is accelerated while a smoke meter is placed at the end of the exhaust pipe and the opacity of the smoke is measured.
The opacity, expressed as a percentage of light reduction, is the degree to which the exhaust obscures a beam of light shining through it.
A number of other states have laws that require heavy duty vehicles to submit to random roadside diesel opacity testing when requested by the appropriate authority. It is anticipated that the U.S. EPA will soon consider legislation aimed at increasing such programs.
