Fleet Maintenance - 28

SPOTLIGHT ON BODY & CAB
»»Fleet technicians can perform a
simple procedure to accurately detect
a leak at the seam of a windshield.
Photo courtesy of Redline Detection

A replaced windshield that was not properly
installed, dried glue or rubber along the seam on
an older vehicle, or even body damage that was
never properly addressed could all be causes of a
cabin air leak. Whatever the case may be, the leak
needs to be addressed sooner rather than later.
Though it may not seem like an issue that
could take a vehicle out of commission, there is
a constant risk of further damage should a leak
remain unsealed.

Cabin leak detection

Smoke out
cabin leaks

Utilizing a smoke machine and a pressurized
cabin, technicians can pinpoint the location
of a leak at the seam of the windshield.

By Tyler Fussner

abin air leaks are more than just a noisy annoyance to the operator of a vehicle; a leaking seam
around the edges of the windshield is hazardous
and a potential catalyst for further maintenance
issues. The ability to accurately detect the location of a leak is critical in ensuring no damage to
electrical systems arises via unwanted entry of
moisture into the cab of a vehicle.

What could go wrong?

Notice of a leaking windshield will usually reach
the maintenance department by way of a driver
telling someone they can hear air hissing into the
cab as they are driving. However, there is more to
be concerned with than the driver's discomfort.
The dashboard in today's commercial vehicle
is full of electrical components and connections.
With the dashboard being the immediate point
of contact behind the windshield, these electrical
systems are susceptible to damage should a leak
be present around the windshield.
A leak can allow more than just air into the
cab - particularly water. Water making its way
into the dashboard, and subsequently contacting
any electrical components, can wreak havoc on
various systems.
The use of electronic logging devices (ELDs)
was congressionally mandated for commercial
vehicle drivers logging their hours of service
through the Federal Motor Carrier Safety

28 Fleet Maintenance | March 2020

Administration (FMCSA), as part of the Moving
Ahead for Progress in the 21st Century Act
(MAP-21). Enforcement for this mandate took
effect in December of 2019. Even if not required
by mandate due to an exemption, many fleets
have opted to install ELDs - typically on the
dash and in close proximity to the windshield.
As with many electronic devices, a vehicle's
ELD is also susceptible to water damage. Should
a windshield with a leaking seam allow moisture to come into contact with an ELD, the result
could be far more costly than merely replacing the
device. This is just one example of critical electrical components in the cab that are susceptible to
damage by way of a leaking windshield.
Other examples of susceptible equipment include
any windshield-mounted devices such as cameras,
radar, or GPS systems. Any and all electrical connections on the dash and around the windshield have
the potential to cause problems beyond damage,
such as operational failure and safety issues. In
some extreme cases, an air leak may allow exhaust
fumes to leak into the cab of the vehicle.

Seal the deal

"Windshields are a big problem; they've always
been a big problem with the gluing aspect," says
Mark Hawkins, manager, technical products, at
Redline Detection, a manufacturer of professional
diagnostic leak detection equipment.

Though a driver can usually hear a cabin air leak,
they can rarely pinpoint the leak's precise location. Technicians acknowledge that the detection
process for pinpointing a leak from the windshield
can be tedious. As a result, technicians have
become innovative, as the tools used to accurately
spot such a leak are not designed to do so as their
primary application.
A maintenance facility most likely already has a
smoke machine on-site for diagnosing intake and
exhaust system leaks or, if servicing light duty
vehicles, finding evaporative emission control
(EVAP) system leaks. A smoke machine can also
help detect cabin wind and water leaks.
Hawkins explains how fleets can perform a
simple procedure to accurately detect a leak at
the seam of a windshield.
Hawkins first recommends turning the key to
the "on" position, without turning the engine on.
Then, a technician would turn on the dashboard
air vent to the "high" setting to allow fresh air to

Though it may not seem like
an issue that could take a
vehicle out of commission,
there is a constant risk of
further damage should a
leak remain unsealed.

»»Experts at Redline Detection recommend
that the cabin leak detection procedure be
done with the smoke machine outputting at
a low pressure. The Redline HD PowerSmoke
heavy duty diagnostic leak detector
has the ability to operate at 2 psi.
Photo courtesy of Redline Detection

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