Manufacturers’ Guidelines Vary for Filter Care
By Frederick Kiel, Staff Reporter
This story appears in the November/December 2010 issue of Equipment & Maintenance Update, a supplement to the Nov. 8 print edition of Transport Topics. Click here to subscribe today.
Heavy-duty trucks built in 2007 and later all have diesel particulate filters, but owners are still confronting perplexing decisions about their proper maintenance.
Poorly maintained DPFs are susceptible to melting or cracking, which can lead to complete ruin and the need to spend as much as $3,000 for a replacement.
Engine makers recommend that the first cleaning be done at 200,000 or 300,000 miles, depending upon manufacturer, though that varies as well according to application and weight of loads. In fact, some maintenance managers say they have seen trucks with 400,000 to 500,000 miles on them, with filters completely unclogged and in no need of a cleaning.
Original equipment manufacturers all offer specific guidelines for owners to follow. Some advise periodic cleanings, but others recommend replacement.
The largest heavy-duty truck manufacturer in North America, Daimler Trucks North America, rejects all cleaning alternatives as inadequate and instead offers owners of its Detroit Diesel and Mercedes-Benz engines a remanufactured DPF, for $600.
“Detroit Diesel has evaluated many types of cleaning equipment, including pressurized air-cleaning devices for in-shop utilization,” Paul Duplessis, marketing manager, Detroit Diesel Genuine Parts, told Equipment & Maintenance Update. “These devices have not been able to provide consistent cleaning results above the specified efficiency.”
Instead of cleaning, Detroit Diesel advises that fleets exchange dirty DPFs for clean, remanufactured units, which sell for about $600.
The company sells the refurbished filters under the “Reliabilt” exchange program, the trademarked name for its DPF remanufacturing process.
Duplessis said that the program employs “a proprietary, three-stage cleaning process that includes heat, air and liquid, which removes more than 90% of ash accumulation” to produce the remanufactured DPFs.
“Detroit Diesel tests a Reliabilt remanufactured DPF with a boroscope,” Duplessis explained, referring to a fiber optic camera. “The boroscope is inserted into the canister to ensure that the unit has been thoroughly cleaned and that there are no hairline fractures below the substrate.”
The DPF owner doesn’t get his original component back however; instead, one that already has undergone the process will be exchanged for the old filter, which Duplessis said helps eliminate most downtime. The old unit will be cleaned and resold under the program, he said.
He said that if a driver or fleet wishes to keep the DPF and receive a replacement DPF, there is an additional core charge of $1,500.
Duplessis said the company offers a two-year, unlimited mile warranty on new DPFs, and one-year, unlimited warranties on remanufactured filters. Recommendations for replacement vary by truck model.
DTNA’s Freightliner, Sterling, Western Star and Thomas Built Bus dealers or Detroit Diesel distributors all offer the Reliabilt exchange program, he said.
Cummins Inc. spokeswoman Christy Nycz said that the company decided that cleaning provided the best maintenance solution for its DPFs.
For the past 18 months, Cummins has dominated the heavy-duty engine market, accounting for 40% or more of all sales monthly.
“Cummins’ base engine warranty covers all elements of the Cummins aftertreatment system — diesel oxidation catalyst, diesel particulate filter, hydrocarbon doser injector, decomposition reactor and SCR catalyst for two years or 250,000 miles,” Nycz explained. “The hydrocarbon doser injector on 2007 products is covered two years or 125,000 miles.”
She said that Cummins maintenance guidelines for DPF filter cleaning depend upon mileage and oil type.
“Maintenance guidelines for ash cleaning are mileage dependent,” she said. “The intervals are as follows: heavy-duty engines using CI-4 oil, 225,000 miles; and heavy-duty engines with CJ-4 oil is 300,000 miles.”
Nycz said that its fleet customers have an option to take their vehicle to a Cummins distributor location or an OEM dealer location for work under warranty.
“Cummins customers have a few options as to where they can go for the DPF ash cleaning,” she explained. “Every Cummins distributor has a DPF cleaning machine at least at one of the branch locations. Most Cummins distributors have cleaning capabilities at more than one location.”
She said that a large number of OEM dealers also have ash cleaning machines, while several large fleet customers have invested in a cleaning machine and can perform the ash cleaning.
Cummins endorses the use of the DPF cleaning machines only for air cleaning.
“Our service procedures don’t require any baking,” Nycz said. “We recommend replacement if the filter has an issue that requires baking. We sell the units on an exchange basis, so we get the used filter back.”
She said that Cummins does not provide a spare DPF while one is being cleaned.
“A customer has a choice of waiting for the DPF ash cleaning process, or the service location can remove the DPF that needs to be cleaned and replace it with a new one,” she said. “This is essentially an exchange type of program.”
She said that Cummins has found that both passive and active filter regenerations, the self-cleaning processes the components periodically undergo, have been working as expected for both its 2007 technology and 2010 technology engines. However, Nycz said that there has not been enough data to say whether the 2010-compliant SCR engines would produce less soot.
“At this point, it is really too early to tell,” Nycz said. “Generally speaking, because of the higher efficiency of Cummins 2010 engines, the need for active regenerations is likely to decrease. However, the DPF ash cleaning interval does not change.”
Mack Trucks Inc., part of Volvo AB, developed its DPF re- placement procedures with an eye toward limiting customer downtime, said John Walsh, spokesman for the truck maker.
“Mack Trucks offers a ‘change and go’ approach,” he told E&MU. “When a customer brings the truck into a Mack dealer, rather than waiting for the DPF to be cleaned, a remanufactured core is installed. A pilot program is also in development for customers who have access to a spare and would prefer that their cores be cleaned and returned.”
He said that Mack’s remanufacturing process begins by blowing air across the filter element and removing ash and contaminants via a powerful vacuum.
Mack believes baking the filters is necessary for effective cleaning, Walsh said.
Walsh noted that filters with a high level of oil or particulate buildup are “baked in state-of-the-art industrial ovens to further reduce ash and contaminants. This is followed by flow testing and a thorough inspection. All filters are then inscribed with identification numbers to track reuse.”
Only Mack DPFs are eligible for the company’s remanufacturing process, available throughout its dealer network.
Mack tells its customers that the best way to ensure proper DPF filter performance is to follow recommended maintenance procedures.
For the Mack filter core, that means every 250,000 miles or 4,500 engine operating hours, Walsh explained.
“It’s important to keep other vehicle systems in proper working order as well,” Walsh said. “In many of the instances where DPF filter cores have been scrapped, the cause was contingent damage due to the failure of another component upstream.”
Mack covers its DPF with a warranty for 24 months or 200,000 miles. If operated in a vocational operation, it is covered for 60 months or 100,000 miles, Walsh added.
The DPF cleaning process Mack uses employs high-pressure air to clean mostly ash, the unburnable components of diesel fuel, engine oil, engine additives and other substances that enter the aftertreatment system after leaving the engine.
That can cost about $150 to $300, most maintenance managers say, though one consultant said the price can be much higher.
If the filter is clogged with soot and unburned fluids such as motor oil, these machines have a component that can bake the filter at high temperatures for several hours to vaporize the waste.
That could set a truck owner back around $400 to $600 per filter.
Paccar Inc., which builds Kenworth and Peterbilt trucks, has just begun distributing its first heavy-duty engine this year, the Paccar MX.
Jeff Sass, general marketing manager of Paccar Parts, a division of Paccar Inc., said that it recommends customers take DPFs to cleaners built by FSX Equipment Inc., which is based in Granite Falls, Wash.
“We have recommended the FSX as cleaner of choice based on our testing,” Sass told E&MU. “The FSX will clean a variety of DPFs, because they come with adapters for each brand.
“Paccar is currently recommending that customers clean our MX engine at 200,000 miles, though we are testing it for additional miles. The key is to make sure you maintain them with the regeneration strategy,” he said.
Still, Paccar recommends that all of its customer fleets stock spare DPFs to avoid downtime.
Navistar Inc., which builds International Trucks and MaxxForce engines, also uses cleaning machines from FSX for its customers.
Brian Mulshine, manager of Navistar’s service development and marketing division, said that since the MaxxForce big bore engines were only introduced in the past year, Navistar is still cleaning filters in the Cummins and Caterpillar engines it has been installing in its trucks.
Beginning with 2010 model engines, Navistar offers only homegrown MaxxForce engines for its Class 8 trucks because all other manufacturers chose a different technology than what Navistar is using to meet 2010 EPA emissions mandates.
“The air pressure system can clean nearly all of the DPFs that we treat,” Mulshine told E&MU. “Very few, I’d say — 10% to 15% — have to go through the baking process.”
He said that he has seen an average national price for air cleaning of DPFs of about $400 and about $100 more for baking. He was referring to the prices charged by all OEMs, not just Navistar.
He said that truck owners have to maintain other engine components upstream at even more regular intervals than DPF cleaning, so as not to damage the DPF.
Volvo Trucks North America did not respond to requests for comment on its DPF protocols.
