may2021 - 19

et's be honest, there are plenty of reasons why
many fleets have developed such an unfavorable view of aftertreatment systems. Most tie
back to three things: inconvenience, downtime, and cost.
" The need for forced regens and more
frequent maintenance often frustrates drivers,
inciting fleets to just disable the DPF (diesel
particulate filter) regen function, " said Alex
Parker, chief marketing officer and executive
vice president of Redline Detection, a manufacturer of diagnostic leak detection equipment. " But disabling DPF regen often leads to
a clogged filter, and that often leads to a costly
derating of the truck. "
Technicians can also grow frustrated
with aftertreatment systems. " Many fleet
maintenance executives report a nine-times
to 10-times increase in technician hours
required to repair and maintain emissions
systems since aftertreatment systems first
came about in 2007, " Parker said.
Much of the aftertreatment system stigma
ties back to those early years. According to
Johan Agebrand, director of product marketing
for Volvo Trucks North America, DPFs had a lot
of metal stresses and potential cracking due to
the extreme thermal expansions and contractions created from temperature differences.
Additionally, for selective catalytic reduction
(SCR) and urea dosing systems, there were
problems with crystallization and an inability
to build up heat in all duty cycles.
" I often remind myself that the diesel
engine has had 140 years to mature, " added
Len Copeland, product marketing manager for Detroit Products, a manufacturer of
diesel engines, e-powertrains, transmissions,
axles, safety systems, and connected vehicle
services. " Aftertreatment systems have only
been around a tenth of the time and have
already evolved rapidly. That said, the very
first aftertreatment systems were not without
some learning opportunities. "
In early systems, Copeland says the top
three issues for many fleets were diesel
exhaust fluid (DEF) dosing systems, DPF cleaning processes, and thermal management.
" Early aftertreatment systems often dosed
DEF pneumatically, " Copeland said. " That
provided excellent atomization, but a dirty air
system could lead to major issues. As such,
most manufacturers appear to have gone to
an electromechanical system that is able to
achieve almost the same atomization with
significantly reduced issues. "
For thermal management, Copeland points
to physical improvements such as exhaust
insulation between the turbo outlet and aftertreatment systems inlet. There have also been
software improvements such as Detroit's AutoElevate and Asymmetric Injection which help
maintain aftertreatment system temperatures
for more successful passive regens.
The most recent version of Detroit's aftertreatment system was released this year to
meet greenhouse gas (GHG) Phase 2 regulations. " With this update, we are able to extend
DPF replacement intervals up to 640,000 miles

or more while further improving the SCR to
increase efficiency at lower temperatures, "
Copeland said. " The DOC (diesel oxidation
catalyst) has also been improved to allow for
lower minimum temperatures during dosing.
These improvements help the system clean
exhaust better at lower RPM. "
Volvo's Agebrand points to other recent
aftertreatment system improvements. " Some
major changes include the fact that the SCR
catalyst actually does a catalytic conversion
in an increased temperature range. Thus,
more variety in load and temperature from
the engine will still result in a catalytic reduction of NOx emissions, " Agebrand explained.
Dosing systems have also improved in both
algorithms and hardware. " This enables the

" Aftertreatment
systems have
only been around
a tenth of the
time [as diesel
engines] and
have already
evolved rapidly. "
Len Copeland, product marketing
manager for Detroit Products

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Detection allows diesel technicians to
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systems to operate in a variety of conditions
and with higher efficiency, " Agebrand said.
" Material production design has also facilitated more compact systems that are easier
to service without reducing efficiency. "

The need for specialized
training and tools
Despite 14 years of aftertreatment system
improvements, some fleets still have a bad
taste in their mouths.
" When 2007 emissions standards were
released, there was little to no training for
the fleet technicians on how to diagnose,
service, and maintain the aftertreatment
systems, " said Randy Griffith, director
of technical sales at Emission & Cooling
Solutions (E+CS), a family-owned company with nine shops nationwide. According
to Griffith, this general lack of OE training
is still the case in 2021. That is why E+CS
specializes in helping technicians understand basic functions and diagnostic procedures for aftertreatment systems.
" We have also found that many parts are
replaced when there is no need to replace
based on age or hours, " Griffith added. For
example, a DOC should last many years, but
a technician is often told to simply change it
rather than find the root cause. " Customers get
frustrated and decide to delete, " Griffith said.
Even for those fleets that have attained the
proper training, more hurdles exist. One is the
need for specialized equipment.
" The cost of tools and equipment needed to
diagnose and service these systems is a newer
problem for fleets, " Griffith said. " Smaller fleets
are particularly affected because they previously could get by without having modern
scan tools and equipment. "
Another challenge is simply the cost of
exhaust items. While exhaust used to be a

Photo courtesy of Redline Detection

May 2021 | FleetMaintenance.com

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may2021

Table of Contents for the Digital Edition of may2021