An "ALMOST perfect" coolant for trucking
and off-highway equipment with long-life
products based on corrosion inhibitors
known as carboxylates of organic acid
(OAT) is available from PrixMax. This new
generation technology has been adopted
by major car and truck manufacturers such as General Motors and Caterpillar, in extended-life specification changes that are already here in Australia.

Research is progressing on coolants
which may last until an engine reaches its major overhaul interval.

For a truck, this could mean no
coolant change in over a million
kilometres, or for a construction machine,perhaps every 10,000 hours.

Caterpillar's EC-1 specification
provides protection for 6,000 hours or four years, whichever comes sooner.

PrixMax long-life coolants also
eliminate the need for the addition of
traditional supplemental coolant additives (SCAs) at 20,000-30,000 km intervals, or every oil drain, or every 250 hours, using chemically impregnated water filters or additions of liquid inhibitor.

Maintaining the coolant in this way
normally replenishes additives that are
depleted as they fight corrosion, and
protects cylinder liners from pitting.

BETTER PROTECTION

Heavy duty engines have gone through
significant design changes and each
evolutionary improvement to engine
technology has placed greater demand on the performance of the coolant. More
than 40% of today's heavy duty engine
repair costs can be attributed to damage
caused by poor cooling system
maintenance. Increased engine power,
cylinder compression pressures and
heavier cylinder components have
increased liner excitation and the chance
of liner cavitation if the coolant is
inadequate.

As each piston strikes it's liner during
the firing sequence it flexes and creates a fine, high-speed vibration. The vibration
creates a low pressure area where the
coolant flows between

the cylinder liner and the coolant itself.
Pitting occurs when air bubbles form
because the coolant cannot maintain
contact with vibrating liners and implode
on the surface of the liner, eroding
microscopic pieces of metal.

If the liners are not protected by an
additive film, pitting can result in a hole
through the liner wall, allowing coolant to
enter the combustion system. When only
water is used as a coolant engine liners
can be pitted to the point of penetration in
as little as 500 hours of operation.

Most conventional coolant
formulations use chemicals such as
nitrites to protect liners, and use high
concentrations of silicates and phosphates to protect against corrosion.
However, the drawback is that these
chemicals deplete or are used up in
service.

For instance, as the concentration of
nitrite decreases, the protective film on
liners reforms more slowly after it has
been worn away by the air bubbles.

If silicate and phosphate compounds
build up in a system, either through
incorrect coolant or SCA dosage, or
reaction with hard water, water pump
seals may be damaged.

Gel-like silicate deposits may form in
low-flow areas when the coolant's pH
drops.

The dosage of SCAs must normally
be carefully monitored to ensure proper
corrosion protection and prevent
overdosing, leading to lead solder
corrosion and radiator plugging.

PrixMax products are formulated
with organic carboxylates which replace
the silicate, nitrate, borate and phosphate
inhibitors and provide the film and superior
pitting protection qualities to that of nitrite
chemicals.

In addition, these carboxylates are
not used up in the process.
The new technology is also said to
provide outstanding aluminium protection,
particularly at high temperatures.