Featured Article: DPF maintenance

John Baxter | April 01, 2010

“Detroit Diesel also recommends seeking immediate support for any indication of engine malfunctions,” Phillips adds. “The fuel and air systems are especially important to the longevity of the DPF.”

Truck application affects maintenance, says Brad Everett of Caterpillar Global On-Highway. “Applications with low-load factors or high-idle times may shorten the cleaning interval life,” he says.

The reason is that a diesel engine’s piston rings don’t seal properly under light loads because cylinder pressure is lower. This increases oil consumption and the amount of ash sent into the DPF. To minimize those, limit idling and avoid stop-and-go and slow driving conditions if possible. n

Maintenance tips

Wear resulting from the use of inferior lubes, excessively long oil change intervals or cooling system neglect will increase ash in the DPF and the frequency of ash cleaning.

Zack Ellison of Cummins says it’s primarily ash in the oil that necessitates cleaning the DPF. Since engine oil consumption is the most basic consequence of normal wear, one way to minimize maintenance required to keep the DPF free of ash is to do all basic engine maintenance religiously.

Poor maintenance may also get you in trouble because of exhaust soot. “A complete PM program is recommended to help ensure that the engine, in general, is protected and running properly,” says Kenworth’s Mike Kalkoske. “Premature engine wear due to poor oil change intervals and failure to maintain the air intake system may result in more soot out the exhaust than the DPF will have the ability to burn off. This may also lead to more frequent DPF cleaning.”

A clogged air cleaner, neglect of the overheads or a charge air cooler leak or outside blockage could reduce airflow into the engine and result in higher than normal levels of particulate from unburned fuel, and the need for frequent regeneration. Another cause of frequent regeneration is the particulate generated directly due to engine wear, which increases oil consumption and soot from the incompletely burned oil, while also reducing compression and combustion efficiency. The only solution for this problem is an overhaul.

ASH CLEANING. Partial clogging of the DPF with ash will not produce enough backpressure to have a significant effect on fuel consumption. However, Mack’s David McKenna and Kalkoske say ash could affect fuel economy by hampering the ability to burn off soot. McKenna says, “The first indication of a full ash load is the increased frequency of active regeneration events, which is caused by the lack of space within the filter to trap particulate.”

Always clean out the ash when you get an indicator light. Clean at the specified interval until experience shows the DPF is accumulating minimal ash.

CHOOSING YOUR LUBE. Using the oil that meets the manufacturer’s requirements is critical, not only to minimize engine wear but to minimize the amount of ash each quart burned will put into the DPF. Industry experts support use of the newer CJ-4 oils, including Cummins, the one engine manufacturer that allows use of CI-4 oils with DPFs. Ellison says, “Cummins has allowed for the use of either CI-4 or CJ-4 oils with EPA-07 engines. This is the same for our 2010 products. While CJ-4 oil is not mandatory for use in EPA 2010 ISX15 or ISX11.9 engines, it is recommended so as to optimize the maintenance interval for the diesel particulate filter.”

While all CJ-4 certified oils are extremely low in ash, you also have the option to shop for oil by looking for the lowest total weight of ash. Detroit Diesel’s Amanda Phillips says, “Low ash content by weight is important to the performance of the engine as it relates to ash accumulation.”

FUEL FILTERS. Phillips also says it’s important to change fuel filters at recommended intervals. When intervals are extended, it may cause trouble because of poor combustion or fuel impurities getting trapped in the DPF.

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