Mullenax,
My 07. 5 6. 7 has a sooted up tailpipe and rear bumper. Looks like a 5. 9 tailpipe. Started sooting up at about 2000 miles and has stayed that way. Now at 31,000 miles. Only mod is that I removed the muffler. DPF and Cat never touched.
I mentioned the soot concern to my Dodge service advisor (more like a receptionist) who politely but patronizingly told me "sir, it's a diesel. Diesels do that. " I knew I was wasting my time at that point. I have never had a message on the overhead saying anything about the DPF or "catalyst full" or anything, only "system OK". I always drive a minimum of 35 miles each time out. No idling and no tooling around town. The truck runs great. Mileage is ok not great.
Is there some way I can get an intelligent person to listen to my concern about the soot? Should I even pursue it? My dealer went belly up and was purchased by a large conglomerate car dealer. I'm uncertain about the skill and training of their techs.
My concern is that I'll be stuck with a big repair bill at some point. There's no emission testing in my area, so if it isn't hurting the truck, I guess I don't really care if the DPF is cracked.
I would appreciate hearing your perspective.
Thanks! Merry Christmas... (we can still say that here right?)
Thanks and belated "Merry Christmas " to you ( Santa Claus is Still alive and well here in Texas).
As I stated above in my previous post, If your tailpipe is "Sooted-Up",You have a cracked DPF.
As to your question if the cracked DPF will cause problems, the short answer is, It depends,There are a lot of variables that can cause a lot of issues. One of the first variables that can make a difference depend on what calibration level your ECM is programed. Some of the early calibrations (even on 08 and 09 models) were excessive soot generators or were not as capable of handling the soot loads seen at the DPF.
Before I get too far into this you need to go here:
https://www.turbodieselregister.com/forums/6-7l-engine-transmissions-2007-5/213869-regeneration.html
This will give you a better understanding of what I am talking about.
Before I get into the issues that a cracked DPF can cause, I think it would be helpful to understand what causes a DPF to crack in the first place. Assuming that the DPF was not damaged by any outside abuse, ie:hit by road debris,truck grounding on a rock,external damage... etc.
We all know by now that the main reason for DPF is to capture and store the "Soot" particles (Particulate Matter or PM) in the exhaust gases as they exit out of the exhaust system. When the amount of "Soot" stored in DPF gets to a certain level (called "Soot Load") or the ECM internal counter gets to a fixed level, The ECM will then enable the start of a Regeneration Event. The Regeneration event will then, through exothermal oxidation, turn the captured "Soot" into Ash which is stored in the DPF.
Now we have to get small. Soot particles are made up of mostly carbon but attached to and absorbed by the soot particles stored in the DPF are other particulates like,Hydrocarbons (unburned diesel fuel),hydrated sulfuric acid,polynuclear aromatic hydrocarbons,sulfur... etc. These particles are called Souible Organic Fractions (No,there will not be a test on this). The only reason I mention these Souible Organic Fractions (SOF) is because of the roll they play in the demise(cracking) of the DPF.
Soot exothermal oxidation occurs approximately at the temperature of 1022 degrees Fahrenheit. This is the point of auto ignition. Once the Soot ignites the temperature of the DPF will continue to rise to approximately 1200 degrees Fahrenheit and maintain this temperature during the complete "De-Soot" cycle. But, This is where the SOF comes into play, if the "Soot Load" of the DPF is high and the SOF of the "Soot" is high, mostly the HC load, once the Regeneration Event is started and reaches the point of auto ignition and the SOF auto ignites the the temperatures will continue to raise up into the 1600 degree Fahrenheit range. If the temperature stays in the 1600 degree range for any length of time the ceramic in the DPF will crack.
Now,to your question, does it matter if your DPF is cracked and will it cause any problems down the road.
As the "Soot Load" of you DPF rises the back pressure on the exhaust system also rises. This rise in exhaust back pressure requires the engine to burn more fuel to maintain the same amount of power output it did without the exhaust back pressure. If the DPF is cracked it can lower the exhaust back pressure, therefore the engine does not have to work as hard to maintain the same amount of power output. This is part of the explanation for high fuel mileage claims from some of my customers. Also the ECM uses a DPF pressure sensor to monitor the "Soot Load" of the DPF. This pressure sensor measures the difference in the inlet and outlet pressure of the DPF to determine if the exhaust aftertreatment system needs to be regenerated. If the DPF is cracked the the pressure differential is inaccurate and so the ECM thinks the "Soot Load" is low and will not enable a regeneration until the counter threshold is reached. This means less Regeneration Events so inturn better fuel mileage. All this sounds like a good thing,less Regeneration Events, Less exhaust back pressure, Better fuel mileage. Whats not to like?
Here's the reality part of it (you knew reality would hit you at some point didn't you?). The Trucks that I Get into the shop that have a cracked DPFare "Soot Loaded" catastrophes. The DPF is stopped-up, the NAC is toast,The DOC is fried , The EGR valve is sticking, The turbo slide ring is sticking... etc. I have found that with a cracked DPF the system does not do enough Regenerations and the Soot continues to build in the system until every thing is stopped-up with Soot to the point of failure. Usally this takes time before it happens,but it will happen. Alot depends on your drive cycle. since you have been able to get 29000 miles with a cracked DPF then your drive cycle is enough to keep the Soot down enough so far, But I can assure you that it is building up, just slower than most. My advise is to have the DPF replaced.
As to your question, Is there any intelligent life out there? (My words,sorry could pass that one up) There are alot of intelligent up to date Technicians out there, But there a alot of misinformed and uneducated (as far as diesel engine and exhaust aftertreatment systems) technicians also. You would have to ask my customers if I'm any good, Maybe someone on this forum that is in your area might be able to guide you to a "Good" diesel technician.
Mike Mullenax
Attention: TDR Forum Junkies 
