Fleet Maintenance - 29

impede the function of the system,
Smith continues. Some of the small failures include air leaks from torn gaskets,
stretched clamps, ripped couplers,
which can cause inaccurate readings to
the pressure and temperature sensors,
electrical faults of the sensors and EGR
valve, and an increase in soot. This soot
increase can not only damage the EGR
system, but the turbocharger as well.
Another common challenge with
EGR systems is coolant leaks, Daimler's
Young notes. Young recommends
pre-trip visual inspections to help mitigate larger problems.
When these problems arise, they
affect not only the EGR system, but the
engine and aftertreatment system as
well. In some instances, components in
the EGR system may need to be replaced
in order to fix the problem.
EGR valves and coolers can be replaced
with either brand new components or
remanufactured components, Smith
explains. Brand new parts typically have
the best value as they have not been used
before, where with a remanufactured
part it is impossible to know what the
part went through with prior use and
how effective it will be moving forward.
"Fortunately, the aftermarket has the
opportunity to step in and analyze the
main failure points on these parts and
can redesign them to make them more
efficient than the original manufacturer
and withstand the operating environments for longer service life," Smith
says. "At Dorman, we have taken all the
major failure modes of EGR valves and
coolers and redesigned them to have
a longer service life than the original
components that came on your engine."
Dorman has taken the usual bar and
fin style of EGR coolers which tended to
trap soot and upgraded some of their
coolers to a spiral tube design, Smith
says. This helps prevent clogging as the
soot can move more efficiently through
the cooler. The company has also
upgraded bushings on the EGR valve
as well as added a more robust electric

"[When combined with
a DPF,] EGR and SCR
[systems have] been
proven to reduce NOx
emissions by at least
80 percent in a wellmaintained truck, and
in some systems, even
more than that."
Keven Smith, field analyst
for Dorman Products

motor to withstand the tension caused
by soot and carbon buildup within the
valve, granting the component a longer
service life.

Servicing EGR systems
for peak performance
For fleets to keep their EGR systems
running properly, technicians must have
the necessary tools for diagnosing, maintaining, and repairing EGR systems.
Dorman's Smith recommends technicians have a diagnostic scan tool and
borescope as well as an EGR cooler pressure tester if they are working on these
systems frequently.
"Having the ability to monitor the
operation of the EGR system while it
is in use as well as the functionality to
run tests on its components is extremely important in diagnosing what has
failed. This will narrow down your
troubleshooting procedures to a target
area of the system where the fault is
occurring and, in some cases, point you
directly to the component that is faulty,"
Smith says of using a diagnostic scan
tool. "Aside from a diagnostic [scan tool],
my personal go-to tool [is] a borescope,
which allows me to take a look inside
the components without disassembling
the entire system to inspect."
It should be noted, however, that
many EGR components are not serviceable and are not recommended to be
disassembled, Daimler's Young says.
This is where training comes in. As
with any heavy duty vehicle system,
training is crucial to properly diagnosing and maintaining the EGR system.
"Understanding how they operate
and knowing what sensor readings
should be when the system is operating properly is key to spotting where
your fault may be," Smith says. "There
are many companies and schools that
offer training on EGR systems."
Another aspect of maintaining EGR
systems is cleaning them. Like many
engine components, the EGR system
can become clogged with soot and PM.
Not all components of the EGR system
are able to be cleaned and reused;
some fleets will just have to replace
components.
"When it comes to the EGR cooler
[itself], there are several companies
nationwide that can successfully wash
out the EGR cooler with a high-pressure
water-based cleaning solution," Smith
says. "The only drawback is that you still
have a used EGR cooler that may fail
soon after reinstallation. This is similar
to using a remanufactured EGR cooler."
In addition to proper maintenance
and cleaning of the EGR system, fuel
type also plays a role in reaching peak

EGR Intake
Throttle

Intercooler

Intake

EGR
Valve

Diesel
Engine

EGR
Cooler

Turbocharger

performance, Young notes. Ultra-low
sulfur diesel fuel is vital to keeping the
engine, aftertreatment system, and EGR
system functional and long lasting.
As EGR technology continues to
progress, the significance of keeping
up with proper maintenance practices is more important than ever. A
technician cannot do their job without
thorough training and the correct tools
and equipment.

		»This image depicts how the EGR
system functions. Exhaust gases exit the
exhaust manifold through the EGR valve,
then enter the EGR cooler to reduce the
gas's temperature, Dorman Products'
Kevin Smith explains. Once cooled,
the gases enter a crossover pipe where
they are mixed in with the fresh air
charge to reenter the engine cylinders.
IImage courtesy of Dorman Products

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Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance
