Fleets running post-2007 model year trucks will soon need to develop a diesel particulate filter (DPF) cleaning program. While the DPFs, found on all truck makes since 2007, have thus far exceeded EPA...
Diesel particulate filters have been quietly going about their business relatively problem-free since they were introduced in 2007. But as they come due for their first cleaning, a major fleet says there's cause for concern.
Fleets running post-2007 model year trucks will soon need to develop a diesel particulate filter (DPF) cleaning program. While the DPFs, found on all truck makes since 2007, have thus far exceeded EPA requirements for longevity, some fleets are beginning to pull the first of those filters for cleaning and are making some alarming discoveries in the process.
After exploring the various options for having its DPFs cleaned, Bison Transport opted to invest in the necessary equipment and do its filter cleaning in-house. It’s no small investment, with each of the company’s three FSX DPF cleaning machines costing about $80,000.
However, what’s more upsetting than the cost of the equipment, as far as director of fleet assets Itamar Levine is concerned, is the potential costs of replacing the significant number of cracked filters the company has discovered. So far, Levine said about one-third of the DPFs pulled off Bison trucks have had hairline cracking along the filter core, Levine said. He’s frustrated that the filters are no longer covered by warranty and the OEMs seem to have no answers as to what caused the cracking. Levine is confident the cracking wasn’t caused by the way the fleet operated its vehicles.
“We can’t do anything to make that filter crack by the way we operate the truck,” he said. “This whole issue is really puzzling to us. The frustrating part is, I seem to be the only guy who’s having this problem according to the OEs. It’s definitely not something just Bison Transport is going to see. This is something we’re going to hear a lot of talk about six months down the road or a year down the road.”
Initially, Levine was replacing each of the cracked filters. But at a cost of a couple grand each, it was no longer feasible to do so. Since then, he has put dozens of cracked filters back into service, yet he wonders if they’re doing the job they’re designed to perform.
“I’ve installed dozens of cracked DPF filters back onto my tractors, which may not be the right thing to do as far as having the system do what it’s supposed to do and clean the air,” he said.
What exactly has caused the cracking remains a mystery. There are many theories, but the one Levine believes is that the cracking was caused by specific events, such as the many EGR valve failures Bison experienced on its early generation EPA07 engines.
A catastrophic event such as an EGR valve failure can cause excessive heat in the filter, Levine said.
“I’m absolutely convinced that the many other problems we’ve had with those engines over the last two to three years and the many EGR valves we’ve had fail, that every time you have one of those events where you create really high heat build-up in the DPF is what’s causing this,” he said. “Every time one of those (EGR valves) fails, you are creating tremendous stress in the exhaust system and overloading the DPF and creating really high temperatures. The only thing that’ll crack the DPF is if it runs too hot.”
Levine said he’s frustrated that suppliers haven’t been more accountable and he’s surprised more fleets haven’t yet had similar findings. At this year’s Technology and Maintenance Council meetings, Levine stood up during a Shop Talk forum and voiced his concern. To his surprise, not one other maintenance manager in attendance complained of similar problems. Levine feels that’s not because their filters are fine, but rather because they’ve yet to clean and inspect them.
“In talking to other fleets, it’s all Greek to them right now,” he said.
For now, Levine said he’ll continue putting cracked filters back into service, but he’d like to see the issue addressed -even if it means bringing it to the attention of the EPA. In the meantime, the fleet’s putting its new cleaning machines to good use and shortening cleaning intervals in hopes more frequent cleanings will help prevent further cracking.