Cummins Diesel Aftertreatment System Video

Mechanics Hub - October 29, 2013

I found this animated video of the Cummins Diesel Aftertreatment system commonly known as SCR (Selective Catalytic Reduction). I need to get familiar with this system since we have been buying International buses since 2010.

Navistar was only using the EGR to reduce emissions to 2010 standards along with buying credits so they did not have to include the diesel particulate filter/SCR system. Now that they can not meet the emissions Navistar has partnered with Cummins and will be installing ISB diesel engines in their highway and buses by 2014.

This makes me happy because...I love the ISB diesels. With that being said I have to know how the SCR system works and I also need to start storing DEF (diesel exhaust fluid).

The DEF reservoir is supplied by the OEM and is heated but I heard the heater only operates when the ignition key is on RUN. The DEF has a portion of water in it and I'm just wondering what happens when it gets to 20 below in the winter time and the tank freezes? I suppose you will have to wait an hour for the heater to thaw the fluid.

Here is the technical explanation of the process. The video explains it as well but I want to write it down here so it gets ingrained in my brain :)