Heavy Duty Trucking, February 2018

DPF as well such as leaks and internal oil consumption Any liquid such as fuel oil or coolant that makes it into a cylinder and eventually into the exhaust stream will foul the DPF and lead to premature plugging and perhaps permanent damage to the diesel oxidation catalyst the DPF or worse the SCR Contamination of the SCR can interfere with NOx conversion says John Moore Volvo Trucks product marketing manager for powertrains Once they have been damaged by coolant or oil contamination they have to be replaced They cannot be cleaned or repaired Since the SCR is downstream of the DPF the likelihood of contamination is slim but if a severe problem goes unchecked for a long time the risk is higher SCR maintenance Most of this story has been devoted to DPF maintenance because thats where most of the expensive and time consuming problems occur The fact is the SCR side of the aftertreatment system requires relatively little maintenance Nachtman says the only scheduled maintenance for Navistars SCR system Cummins Single Module aftertreatment is changing the diesel exhaust fluid tank neck filter which is in place to keep grit and debris out of the tank Its a scheduled item at 30000 miles he says Thats all If theres a problem with the DEF line return pump you replace it Theres really no other maintenance except to clean the tank if it becomes contaminated with something like diesel fuel Volvo and Mack have added a DEF quality sensor to the tank to alert the driver to a potential contamination problem That came with the on board diagnostics updates in 2016 Moore says Previously the system would not detect bad DEF Instead it would guess at the source of the problem sometimes targeting a sensor Youd get some incorrect fault codes and possibly an engine derate because it wasnt seeing the proper conversion rate Now youll see a code for bad DEF Mack and Volvo have a scheduled DEF filter and pump filter replacement at 150000 miles Paccar has a service interval for the DEF filter and dosing unit at 300000 miles Still DEF tanks can be contaminated and that can cause problems with the DEF quality and ultimately NOx conversion If only water has been added to the DEF tank drain the DEF tank flush with distilled water and refill with new and or known good DEF advises Paccar With other contaminants such as diesel fuel hydraulic fluid coolant or windshield washer fluid the tank pump filter could require replacement dependent upon the severity of contamination The good news for fleets is that aftertreatment system maintenance is getting easier and less complicated but only for those with newer trucks Original equipment manufacturers have improved the efficiency of these devices and in some cases the packaging Those changes mean some fleets will see fewer regen events on their DPFs and their cleaning intervals have in many cases been extended Maintenance of the SCR and DEF systems remains minimal Fleets with older trucks however will likely see their DPF regen intervals shorten as ash clogging builds up to solid blockages Many with 2014 ish trucks will be coming up to the DPF cleaning replacement intervals Rather than get caught on road in an expensive predicament take a proactive step and schedule a cleaning or replacement before the DPF plugs up for good and sticks you with a 1000 bill and three days downtime anti oxidants developed before the introduction of DPFs The new API oil classifications that came into being in late 2016 contain less of this material which means that if youre using a CK 4 or an FA 4 oil there will be less of that type of ash winding up in your DPF These newer oils contain less ash than older oils so theres less chance of DPF fouling says Jim Nachtman Navistar heavy duty product marketing director The new cleaning intervals we publish for our A26 engine are based on these new oils You can continue to use older oils like a CJ 4 or CI 4 but youll have to dial back the DPF cleaning interval Even healthy engines consume small amounts of lube oil and most of that ends up going into the exhaust explains Shawn Whitacre senior staff engineer engine oil technology with Chevron Because lube oils contain metallic components from additives and from wear metals some of these incombustible materials accumulate in DPFs and other exhaust components When choosing oil be sure youre using the right product for your engine The CK 4 oils are for current and older engines and are backward compatible to older oil categories The FA 4 fuel efficiency oils are designed for newer engines 2016 and beyond and are not backward compatible because of lower high temperature high shear viscosity Oil has other ways of making it into your Pneumatic filter cleaning works on about 80 of filters sent in for cleaning More thorough liquid washes are recommended for more thorough cleaning PHOTO FSX INC HDT FEBRUARY 2018 52 WWW TRUCKINGINFO COM