Issue link: https://read.dmtmag.com/i/59415
severe service DPFs as maintenance tools Dirty exhaust enters the DPF, and soot is trapped on the coated ceramic honeycomb material inside the filter, rendering the exhaust exiting the filter clean. PICKING THE SHOP One DPF downside is it may mask serious engine problems that used to be easy to diagnose. On older engines, when you saw white or black smoke streaming from your exhaust stacks, you knew you had a blown turbo, a faulty injector, worn rings or other issues. Today's DPFs will let little of that smoke escape. " That is a general con- cern for the entire indus- try," says Rakesh Aneja, senior manager for product engineering with the Daimler Truck Group. With the filter masking exhaust smoke, "the diagnoses become more challenging. It may lead to aftertreat- ment failures if it is ... load- ing up the filter more and more." Frequent clogging can warn of a problem with an injector, an air handling system or oil consumption, says Myron Birschbach of Inland Power Group. Such early notice could help reduce repair costs and potential downtime. Engine maintenance will pay dividends by extend- ing DPF cleaning intervals. Proper maintenance includes: • Regular oil changes to keep wear and oil consump- tion under control • Ideally, use of CJ-4 oil to extend the cleaning interval • Minimal idling. Navistar's Mark Ehlers says to watch for head gasket leaks that could allow coolant into the exhaust stream, causing a loss of heat that inhibits the system's ability to burn off soot. Even a small but steady leak of just five gal- lons over time could cover the platinum oxidation catalyst designed to accel- erate regeneration, leaving the unit subject to frequent clogging. Clean the hydro- carbon injector as recom- mended to preserve the spray pattern. Repair any exhaust leaks right away. 42 OVERDRIVE APRIL 2012