That's the way the DPF crumbles

That's the way the DPF crumbles

In a few months, we in the shop have seen the same failure on three different trucks. These engines were different model years with different after-treatment configurations. Two had a DPF and SCR, while the other only had a DPF. The failure mentioned is the DPF outlet cracking horizontally and vertically, resulting in large chunks of DPF falling off into the exhaust system. One was damaged so severely that it began to crumble into pieces. The photos of the failures shown are also on our social media pages if you are interested in looking closer. In these cases, there were few to no fault codes indicating that something happened to the filter. The issue was only discovered upon physical inspection; this is pretty common for this type of failure. A cracked or slightly melted filter will still perform but will not be as effective.

When the temperature in the DPF rises quickly or uncontrollably, the filter will crack. You can potentially crack a filter if you are pulling a very long hill and then suddenly come to an idle. The elevated temperature causes the soot to burn rapidly. When you stop this process by coming to an idle, the filter cannot cool down because the exhaust flow is so low. Every driver on the road should know that pulling a hill and then shutting your engine off is not good for your turbo. Take the idea of rapidly heating and cooling metal. Cool that hot metal down too quickly, and it becomes brittle, having a greater chance of catastrophic failure. The idea is similar to your DPF, but it needs more than idle to cool down safely. High idle may suffice, but you must slowly reduce the temperature to keep your DPF healthy. This may sometimes require you to drive at a low load for a short period; we are talking about temperatures reaching more than one thousand degrees. It may sound like a time-draining inconvenience, but we can assure you that replacing hard-to-find expensive emissions parts is far more time-consuming and costly.

Another reason DPFs crack or fall apart is a lack of regenerations or insufficient/incomplete regens. What we mean by insufficient is that your filter is collecting more soot than it burns. This happens when something is wrong with the system, and although newer engines are better at catching this issue, it does not mean that it will not occur over time.

When a DPF is overloaded and suddenly reaches a temperature where the soot can ignite, it can devastate the emissions system. It's like having a massive pile of dried brush and lighting it with five gallons of gasoline. It goes up in flames quickly! The same thing happens inside of your exhaust. If your filter has a lot of soot, and you finally do a regen or pull that hill after idling for 8 hours, you're setting yourself up for a failure. It harms your DPF and can also transfer that excess heat to the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalyst Reduction).

A catastrophic emissions failure was brought in only a few months ago. This truck was being inspected for an issue entirely unrelated to emissions. Still, the owner clarified that the system was only a few months old when signing in. Once set up on the Dynamometer and ran a couple of times, all seemed well with no signs of fault. A second engineer joined the diagnostic process and monitored the ECM while driving the truck. On the first run, the monitoring engineer noticed that the DPF temperature was steadily building quickly. The truck went into an automatic shutdown state, and our engineers had no choice but to start a physical inspection of the truck. When all signs began to point towards the DPF being blocked, it was removed to find that it had been completely blocked with ash. The ash had ignited while being pulled down on the Dynamometer. The intense heat of sixteen hundred degrees traveled to the DOC, and SCR rendered them useless. Our team eventually found that the shop that had initially warrantied this customer's Emissions system had installed it incorrectly. It was also suspected that there was an internal issue with the motor, which would produce excess soot, but run within the high end of OEM specification, preventing it from throwing any codes or derates. The last and most recent case may be the worst, most severe case of DPF degradation that has come through our doors. In much the same way as the previous examples, this DPF was subjected to excessive heat and pressure throughout its life. With it unable to run a regen due to the DPF and SCR being completely blocked, the substrate began crumbling inside the DPF canister.

Nightmare scenarios like this can be prevented by changing your driving, letting your truck regen if and when it wants to, and frequently having your DPF inspected. Pull it down and look at it or have it looked at by a professional. With emissions cleaning services such as Diesel force and DPF Alternatives in reach of every driver, catching these issues early has never been simpler. It will save you time and money in the long run.


Written by:

Leroy Pershing

Jordan Greathouse


Pittsburgh Power

3600 S. Noah Dr

Saxonburg, PA, 16056

(724) 360-4080