General inspection of components
Navistar’s Nachtman recommends the driver
check the level of coolant in the coolant reservoir
daily.
“Engines should never consume coolant, or
leak coolant,” Nachtman says. “If the coolant
level is low, the driver should reach out to the
service provider and have the vehicle looked at.”
He adds that the engine, hoses and the ground
28 Fleet Maintenance | May 2018
beneath the vehicle
should also be checked
for wet areas that may
indicate a coolant
leak. Hoses should be
checked for abrasion,
and clamps should be
kept secure and tight.
Other areas to inspect
include the fan belt and
the fan itself, as well as
the water pump.
“Look at the belt
for any cracks in the
rubber or any chunks
missing,” Nachtman
says. “As well as looking
at the fan blades
themselves, make sure
there’s no signifi cant
chips or cracks.”
“Water pumps have
what is called a weep
hole,” he adds. “It’s
good to look at the
water pump to make
sure there is no coolant
leak, which could
indicate a bearing or
seal failure.”
Misconceptions
with coolant
While inspecting the
components is crucial,
keeping up with the
coolant is arguably just as — or more — important
to maintain a fl eet’s cooling systems.
“Coolant is oft en the most neglected fl uid in a
vehicle, which is surprising because some sources
have pegged cooling system failures as the
cause of half of all engine failures,” Prestone’s
Dilley says. “Regular testing of the coolant to
ensure proper nitrite, pH and EG concentration
will go a long way to ensuring engines run
smoothly. In addition, if fl eets are mixing coolant
and water onsite, it is very important to ensure
they are using high-quality deionized water.
Contaminants in tap water can easily throw
off the balance in the cooling system or introduce
foreign material that the system cannot
neutralize.”
A common misconception with coolants and
additives is that the same color is always compatible,
even if it comes from a diff erent source or
brand. However, that is oft en not the case.
“Fleet service managers should know what
coolants and additives are being used in each
power unit, and should not rely upon coolant
color to determine product,” Detroit Diesel’s
Daniels says. “Because diff erent OEMs have
diff erent coolant requirements, it’s important to
refer to OEM and coolant manufacturer recommendations.
It’s also important to maintain
meticulous and up-to-date records on cooling
system maintenance.”
He adds that fl eets should always refer to OEM
documentation for change intervals and cooling
system maintenance procedures.
Select suitable additives
Additives can extend the life of some coolants,
but Dilley says that Prestone only recommends
supplemental cooling additives (SCAs) and
extenders.
“SCAs protect coolant systems from corrosion,
the buildup of harmful deposits and
control the pH balance,” Dilley says. “SCAs
replenish corrosion inhibitors and protect all
cooling-system metals.”
SCAs are used for pre-charged, conventional
low-silicate formula coolants which are usually
pink or purple and need to be tested and charged
every 25,000 miles, Dilley explains. Extenders
are used for nitrite organic acid technology
(NOAT) formulas, which are usually red and
need to be recharged at 300,000 miles or 6,000
hours of service.
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» Coolants are transitioning from older
formulas that contain nitrites to new
nitrite-free extended-life formulas.
Photo courtesy of Prestone
Which glycol is best?
At a basic level, the primary chemical composition
of antifreeze (or, coolant) used in diesel
engine cooling systems comes in two categories:
Ethylene glycol (EG) and propylene glycol (PG).
“EG was first introduced by Prestone in 1927 as a
nonflammable solution to the freezing and boil-over
of cooling systems,” says Colin Dilley, vice president
of technology at Prestone Products Corporation.
“To this day, EG is used in the vast majority of
vehicle cooling systems. EG has superior heat
transfer properties as well as superior freeze and
boil-over protection. It is also indefinitely stable.”
“PG has been on the market for decades. It is priced
at a premium to EG, and does not provide any performance
advantages over EG,” Dilley explains. “Very
few factory fills are actually PG and most of these are
agribusiness-based applications.”
One advantage to PG is that it is safe to use
around animals and food products. Therefore,
it is commonly used in the agriculture industry
and in applications such as pipe antifreeze.
“PG antifreeze is less toxic and more environmentally
friendly than ethylene glycol antifreeze,”
says Brian Daniels, manager of powertrain and
component product marketing at Detroit Diesel.
In fact, PG is considered so safe that the U.S. Food
and Drug Administration (FDA) has approved it
for use as an additive to maintain the moisture
in some consumable products such as medicines,
cosmetics and food. PG can also be found
in paints and plastics, as well as for the solutions
used to create artificial smoke or fog.
While PG is sometimes used as an additive for human
consumption, it is important to note coolant using this
same chemical compound should not be consumed.
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