The Cummins ISB diesel engine needs a regen just as much as any other diesel engine on the road. Knowing when is important and reducing down time happens by following a very simple step. If the diesel particulate filter builds up a restriction then the onboard computer signals a regen while the bus is driving on it’s route. This is called a passive regeneration. But this may not be enough over time because of the constant diesel engine exhaust gases requiring treatment down the line to reduce emissions.
The raw diesel exhaust is not pretty and wears engines out slowly but surely. The EGR valve directs certain percentages of exhaust to the intake depending on engine load and speed. The exhaust gases are cooled by the EGR cooler to reduce the temperature which in turn reduces NoX (oxides of nitrogen). The final product of soot and ash collects in the DPF and has to be cooked out by way of a regen. The heat produced by the engine and extra fuel injection breaks down the soot to ash which works it’s way out of the exhaust system.
If a parked regen does not work the DPF has to be removed and cleaned at a dealer with the special equipment to cook out the soot and ash. They charge around 400 dollars for this procedure and I have been finding it worth it in most cases. A new DPF is four to five times more money so maintenance before replacement is well worth the time and effort. In this case I was just doing a tune up regen to get any residue out of the DPF. This being a Cummins ISB it also has the SCR (selective catalytic reduction) attached to the rear of the DPF.
Cummins developed this add on system and it’s done them wonders. The additional task of adding diesel exhaust fluid is nothing when you consider how great the SCR works to keep the exhaust clean. International and Mercedes diesel engines fell by the way side because they could not keep up with demands from EPA. Cummins met the emissions standards and are still going strong. I am a believer in the ISB diesel which has kept our fleet running. Cummins has towed the line right from the beginning and that is why I am a life time customer. I hope after you have read this article you will be convinced as much as I am.