HOW TO CLEAN A CONTAMINATED FILTER

Diesel engines are widely used in transportation and industrial applications due to their high efficiency and power. However, diesel engines also produce harmful pollutants such as particulate matter (PM) and nitrogen oxides (NOx). To reduce these emissions, diesel engines are equipped with various types of aftertreatment systems such as Diesel Particulate Filters (DPF), Diesel Oxidation Catalysts (DOC), and Selective Catalytic Reduction (SCR) systems.

Over time these systems can become clogged and contaminated, which can lead to decreased engine performance and increased emissions. In this article, we will discuss how to identify contaminated DPF, DOC, & SCR filters and how to clean them effectively. Whether you are a diesel engine operator or a mechanic, we aim to help guide you with the information you need to keep your aftertreatment systems running efficiently and effectively.

 

  Step 1 - Remove your Aftertreatment System

      Sean (owner) working on removing aftertreatment system components.
      Removing the filters from an isuzu aftreatment system.

       

          • Start by removing and inspecting the Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), and Selective Catalyst Reduction (SCR) filters for signs of face cracking or burn-through due to overheating of the DPF.
          • Isuzu aftertreatment system with filters removed for cleaning.
        An Isuzu aftertreatment system w/ DPF, DOC, & SCR removed for cleaning.

         

          • If horizontal or vertical cracking or melting occur, then a full replacement of the DOC, DPF and SCR filter system is in order. Possible surface cracking can occur that may not continue throughout resulting in a yellow tagged filter. Additional testing is performed to determine if internal melting or cracking has occurred*.
          *A yellow tag filter will show signs of wear and potential signs of pending failure. In the event your filter is tagged yellow, please consult with your cleaner on your options.

           

           

              Step 2 - Cleaning your DOC / DPF / SCR filter(s)
                  • The most common method for this is baking, which uses heat to burn away soot from the filter. For a more thorough deep clean, you can use a blast cabinet with compressed air and vacuum technology, LIKE US!

                 

                    Inside picture of open kiln.
                    Olympic filter cleaning kiln

                     

                    Inside picture of kiln while it is firing at 1112 degrees.
                    Olympic kiln firing at 1112 degrees F

                     

                      • DIY methods like water pressure washing can appear to also be an option, though the risk of damaging the filter is high and should be avoided unless you are experienced. If you decide to go this route, then the filter should be left to dry for at least 10 hours prior to re-installation.

                     

                              Step 3 - Clean All Other Aftertreatment Components
                                  • After all contaminants (oil, fuel and coolant) have been cleaned out of the system, disinfect exhaust system piping post-turbocharger up until where it reaches the DOC filter.

                                 

                                  • Clean all temp and pressure sensors with electrical cleaner and make sure NOx PPM sensor readings are valid for optimal DPF/SCR performance; NOx sensors might need replacement due to contamination.

                                 

                                Step 4 - Perform a Forced Regen

                                    • Start the engine and let it run (at Idle or High Idle) for 1 to 3 hours without producing any smoke. During this time, remember to park your vehicle outside in order to allow exhaust gases and possible smoke bills to diffuse into the atmosphere.

                                   

                                    • Confirm that the regeneration system functions correctly. You'll need an advanced diagnostic tool at this stage. If fault codes remain active during the DPF regen process, identify them and replace failed parts before beginning again. In certain cases, two consecutive regens may be recommended to attain optimal temperatures against contamination.

                                   

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                                  Truck driving at sunset with Aftermarket DPF information overlay.