DieselEmissionsInsider2024 - 11

DIESEL EMISSIONS
Troubleshooting Overloaded or
Failed Filters
WHEN NARSA/IDEA asked if I had
any topics to write about, one came
to mind quickly: How do DPF cleaning
facilities troubleshoot overloaded or
failed filters? And who do they share this
information with?
Since DPF cleaning facilities make money
by servicing DOC, DPF, and SCR units, how
far do they go into telling the shop that
dropped it off or the filter owner what the
filter condition was? Or that a further look
into the engine is necessary to keep from
having more aftertreatment issues quickly?
Repair shops make money by doing
repairs. If they remove a DPF for cleaning
and its compromised or needs to be
replaced, they need to dig deeper into
the engine or run diagnostics to see why
the engine has overloaded the DPF. No
one person or shop should be installing a
replacement filter without understanding
and correcting the root cause of the failed
unit they are replacing.
At Diesel Emissions Service, we have also
seen several DPFs sent in for warranty
that had been cleaned a few times within
a short period. Once we dug further, we
asked if a DOC efficiency test had been
completed. The answer was " No, " and
when we asked what repairs had been
completed prior to the replacement DPF
needing to be cleaned, we saw that an EGR
cooler had been replaced. The shop did the
replacement, and sent the truck on its way.
Within a few weeks the truck needed the
DPF cleaned, the cleaning facility cleaned
and replaced the unit back into service.
Then within weeks, the truck needed the
DPF service again. This time, they told
the truck owner the DPF must not be any
good. They installed a new aftermarket
unit. Another 30 days had passed, and the
truck is showing high back pressure and
the truck's owner takes the truck back to
the shop and asks, " What the heck?! " The
shop feels it must be from bad DPF and
sends it in for warranty.
This is why repair shops, including DPF
cleaning facilities, need to get involved
in the troubleshooting process. The shop
should have done a DOC efficiency test
By: Steve Hoke,
Diesel Emissions Service
steveh@des.direct
after the EGR cooler was found to be
defective. The shop should have also done
this same test after the filter plugged up
several times and had to be cleaned.
In this scenario, if the DPF cleaning facility
used a filter cleaning tracking program,
they should have contacted the shop
or customer and advised that engine
diagnostics needed to be completed
as it's not normal to clean a DPF more
than once a year or 75,000 miles under
normal conditions.
The shop finally did a DOC efficiency test
and replaced the poisoned DOC. Most
people still don't know that ethylene glycol
from coolant and excessive lube oil can
stop the regeneration features from a
catalyst quickly.
Here's the lesson: Anytime there is a DPF
issue, we need to use diagnostic tools to
help us see what's happening with the
aftertreatment system. Most failures to
the aftertreatment system come from the
upstream source, the engine. As a NARSA/
IDEA member, you have access to several
videos from different webinars that were
done as part of the Lunch and Learn
webinar series.
These are available to watch on
http://narsa-idea.org.
March/April 2024 | DIESEL EMISSIONS INSIDER | 9
http://www.narsa-idea.org
DieselEmissionsInsider2024

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