A Good Core Gone Bad: Four Modes of DPF Failure

Among the drivers we know, there seems to be some mystery shrouded in distrust when it comes to the aftertreatment system in your BIG truck. Made up of some rather complex components from the EGR Valve to Oxidation Catalyst, the entire system is designed with one goal: The reduction of NOx emissions.

Love it or hate it, emissions regulation is here to stay which means you’ve got work to do. While EGR Valve and Cooler failures make up the bulk of the trouble our knowledgeable Joe’s encounter, the dreaded (and expensive) Diesel Particulate core failure isn’t far behind. So, what makes a good core go bad?

There are four modes of DPF core failure - Pinholes, Melting, Cracking and Fouling. Each mode is catastrophic and caused by a chemical reaction between the ceramic Corderite substrate in your DPF and the chemical composition of the particulate matter emitted from your diesel engine. Literally, the same ash that your DPF is designed to capture will eventually cause the chemical destruction of the filter. Bottom line, it means that with time and miles, DPF replacement isn’t simply a matter of if, it’s a matter of when.

Pinholes, Melt and Cracking (Figure 1) are all a direct result of prolonged exposure to “alkali compounds” which are a natural by-product of diesel fuel combustion. This reaction, over time, reduces the heat tolerance of the DPF substrate to diminish causing the high temperature environment of regeneration to “melt” or crack the substrate.

Fouling is caused by Coolant leaks from high temperature exhaust gas recirculation (EGR) failure, excess lubricant from engine failure, and fuel from incomplete combustion all possess the capability to enter the exhaust stream and “foul” or contaminate the DPF.

The most economical way to treat your DPF is through regular maintenance - taking advantage of both passive and active regeneration - mixed with interval cleaning in line with your manufacturer’s suggestion. That should help preserve the life of your DPF, but these are hard working machines and as we’ve covered, the normal operation of your truck does irreparable damage to your DPF core.

When replacement becomes necessary? Well, just give your old friend Joe a call or click.

(FIGURE 1)

 

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