Featured Article: DPF maintenance
FUEL. Kalkoske says an inferior grade of fuel may contain impurities that will end up trapped like ash in the DPF.
DOSING SYSTEM. Maintain the dosing system used for active regeneration by cleaning it at specified intervals, normally 150,000 miles or one year. McKenna says coking problems experienced in many engine makes may prompt the need to install a kit Mack provides to drain the nozzle area of fuel when it’s not being used and protect its fuel line from heat. On Caterpillar engines, Cat’s Brent Cluskey says to inspect/replace the ARD spark plug that ignites the dosing fuel at 90,000 miles.
CRANKCASE VENTILATION. Maintain the onboard crankcase ventilation system according to manufacturer’s recommendations. Cluskey recommends the same interval as the spark plug. He also recommends cleaning the crankcase fumes fitting on Caterpillar mid-range engines. The OCV system separates oil from the blowby gases, thus reducing oil consumption and minimizing the amount of ash in the DPF, if properly maintained.
Engine manufacturers say ash cleaning intervals are much longer than forecast.
Cummins’ Zack Ellison says, “We are seeing very few over-the-road customers actually needing to perform a routine ash cleaning for the DPF. Many customers are running 400,000 to 500,000 miles before needing an ash cleaning.”
Caterpillar, even though its DPF with clean gas induction generates a little more exhaust, estimates intervals from 250,000 to 350,000 miles, according to the company’s Brad Everett.
Kenworth’s standard interval is 160,000-200,000 miles, while Ellison says Cummins increased its standard interval from 200,000 to 300,000 miles.
When cleaning becomes necessary, the proper procedure is essential. Detroit Diesel’s Amanda Phillips says, “Customers should take their vehicle to an authorized Detroit Diesel service location to have their original DPF exchanged with a remanufactured core unit.” Ellison says Cummins customers “can choose to wait for the cleaning while in the shop or can select to simply exchange the DPF for a Cummins ReCon Particulate Filter.”
Mack’s David McKenna says a ReMack exchange filter “saves time and money as the filter has been completely X-rayed and cleaned to the highest standard.”
On cost, Everett says Caterpillar has “a flat rate charge that varies from dealer to dealer.” Kenworth’s Mike Kalkoske says, “The cleaning time depends on the cleaning machine used, and amount of ash needing to be removed. An operator should typically expect the cleaning to take 30 minutes to an hour and cost an estimated $250 or more.”
This diagram from Detroit Diesel shows the locations of the various sensors that provide input to the ECM. By analyzing the sensor readings, the ECM can determine when active regeneration or ash cleaning are needed.
1. Diesel oxidation catalyst
2. DOC inlet temperature sensor
3. DOC outlet temperature sensor
4. Sensor junction box
5. DPF outlet temperature sensor
6. DPF outlet pressure sensor
7. Diesel particulate filter
8. DPF inlet pressure sensor