Deals on Wheels #469

DEALS Showcase
COOL
Runnings
Phil Reynolds works in the product
department at PACCAR Parts. Here,
he delves into the cooling systems on
trucks, including the basic operation,
the technology, materials and
maintenance of the cooling system
Copper’s thermal efficiency
is well regarded. The heat
in the coolant coming from
the engine is absorbed in
the copper. Specific ridges
pressed into the copper assist
in air turbulence and contact
to exchange heat with the
flowing air. Source: Air
Radiators. Image: P Reynolds
Beyond the
main materials
choice
of things like
gaskets is
also crucial
When I started out at Kenworth 15-odd
years ago, one comment sits with me to
this day, from our chief engineer at the
time: “Kenworth Australia engineers our
trucks around the cooling package.”
To better appreciate and understand
the cooling systems on trucks I visited
Air Radiators near Geelong.
Firstly, the basic principles of cooling on
trucks. We immediately think of the radiator,
however, charge air coolers, fuels coolers,
oil coolers and condensers are also there
to handle heat rejection and maintain the
systems they are integrated with.
Engine manufacturers like Cummins
and PACCAR look at the components
that make up an engine, like cast iron and
aluminium, work out the different rates of
expansion on those components to then
set the specifications around optimal
working temperature.
Engine manufacturers take care of
bringing the engine up to temperature
through thermostats (that act like a valve
regulating coolant flow around an engine).
They also specify the volume of movement
of coolant around the system with a water
pump, but it is the job of the radiator to
maintain the top end boundaries of the
specified working temperatures.
Things like bullbars, driving lights
and bug screens are all commonplace
on many trucks and they all impact
airflow to the radiator.
Then, there are the truck grille, air
conditioning condenser, fuel and oil
coolers and the charge air cooler all
exchanging their heat with the air before it
arrives at the radiator. Naturally, the engine
fan is critical when additional air flow is
required, yet the greater the efficiency of the
cooling package, the less time the fan needs
The cooling ‘package’ can incorporate
things like air conditioning condensers, oil
coolers, fuel coolers, charge air coolers,
and of course the radiator. Source: Air
Radiators. Image: P Reynolds
to run and this saves on power and fuel.
The materials used are critical to efficiency
and longevity. Copper has stood the test of
time for strength and thermal properties,
and has the added benefit of ease of
repair over aluminium. Many Australian
applications mean the choice for customer
remains with the quality, reliability and
serviceability of the copper-brass radiator.
Beyond the main materials, choice of
things like gaskets is also crucial, along with
replacing the top and bottom tank nuts and
bolts that can stretch over time.
Being a stationary part, the cooling
package receives little service. High
expectations on life means quality
components and construction is a must.
Critical things to be aware of include using
the correct coolant and not mixing it with
other brands.
Hoses and clamps should be checked
regularly and bug screens cleaned. Earth
straps from the radiator are also important
to check and ensure they are intact and
connected to the chassis.
Another part prone to wear, and often
forgotten about, are the various rubber flaps
that seal against hoods and engine tunnels
to ensure cold air is directed appropriately
and to stop hot expelled air from being
recirculated through the cooling package.
Visual checks of your radiator will also
help identify any potential issues. Things
like coolant residue appearing, or your fan
‘on time’ increasing, might be symptoms of a
cooling system in need of an overhaul.
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Special thanks to Air Radiators sales manager Phil Nicol, key account manager Roger Johnston and
applications and projects manager Brooke Killen, who imparted their knowledge to assist with this article.