A Primer On Diesel Particulate Filter And Aftertreatment System Maintenance – Part I

Ask any fleet technician or manager and they will tell you that aftertreatment system maintenance can be costlier and time consuming than any other type of shop maintenance. Not only are parts costs quite prohibitive, but you can expect a reasonable amount of downtime to accompany the work.

The fact is, when these systems were first deployed, plenty of confusion followed. These were intended to be hands-off systems that could self-maintain outside of simple cleaning procedures at regular intervals. Unfortunately, this didn’t turn out to be the case.

An Evolving Understanding

While an overall understanding of these systems still exists, fleets with extended trade cycles are now at the vanguard of that long learning curve. While they will benefit from the hard lessons learned by early adopters, it will be some time before the industry as a whole is confident about maintaining diesel fuel particulate (DPF) and after treatment systems.

For many fleets, coming to the conclusion that things need to be done a little differently from the way they were done before is essential to maintaining aftertreatment order in the shop. With such complex systems, it’s hard for technicians to realize that aftertreatment preventative maintenance is not just helpful, but is necessary.

Of course, some aftertreatment systems may have problems by themselves, but that isn’t the full story. Much of the modern motor carrier’s problem lies in upstream failures. But still, the story doesn’t end there.

Days of Disruption

What many may not initially realize is that the delicacy of an aftertreatment system is susceptible to any number of failures or interruptions. Take a leaking exhaust manifold as one example. While this may have been tolerated a decade ago, today the heat loss could affect passive regeneration performance.

There are a number of upstream failures to worry about, including:

• Leaking fuel injectors;
• Too much idling;
• Leaking exhaust pipes or manifold gaskets;
• Coolant leaks;
• Exhaust gas recirculation cooler leaks, and;
• Sensors or wiring harness failures.

While it’s true that fleets have been hard at work streamlining their preventative maintenance processes, many still don’t understand how important aftertreatment maintenance is. Proactively managing and maintaining these systems will prevent you from having to spend half your day troubleshooting a DPF problem.

Also consider that DPF filters are subject to a lot of potential impact damage and excessive vibration, so make sure you are inspecting the canisters regularly for potential damage, which include any premature cracking or breakage. Also spend time cleaning sensors and any exposed contacts to make sure the connections are not gummed up with dirt or other contaminants.

No Two Trucks Are the Same

The main issue with using a one-size-fits-all approach to predictive maintenance lies in the fact that no two trucks are the same. After all, the condition of the DPF is highly dependent on the duty-cycle it undertakes.

Long-haul trucks, for instance, run consistently high exhaust temperatures, and are less likely to need any parked regeneration. On the other hand, stop-and-go duty vehicles may encounter a situation where the aftertreament system has a problem maintaining itself.

While OEMs used to suggest 300,000 to 400,000-mile intervals between cleaning, many have now come to realize that cleaning may be required a lot sooner and much more frequently. Of course, this all depends on the duty cycle involved.

Consider this, if you are getting a lot of requests for parked regeneration, then you may need to take a look at cleaning the system. Oil contamination can cause sulfated ash to build up within the DPF which, left unchecked, can seriously damage the system.

Always make sure to perform regular checks of the oil and coolant levels to release backpressure. The last thing you want to do is run the risk of face-plugging your diesel oxidation catalyst.

Have all these terms got your gears turning? If so, be sure to stop by for the next Part in our series, where we dig even deeper into the ins and outs of maintaining your DPF system!