MACS Monthly Newsletter - 2017 - MAY1

Total Vehicle Climate and Thermal ManagementTM

May 2017

By Dave Hobbs - MACS Field Correspondent

A CLOSER LOOK AT COOLANT
contributes to the challenge of keeping an engine cool. Add
to that the growing fleet of hybrid electric vehicles (HEVs)
that are using coolant to cool everything from power electronics (inverters and DC-DC converters) to motor generators to high voltage (HV) battery packs. That's the technology side. Now for the human side - customers often have a
special form of dyslexia. What do I mean by that? I mean they
look at the label on a gallon jug of automotive coolant on the
shelf at the supermarket or DIY auto parts store and read the
words "Long Life Coolant" (i.e. DEX-COOL). They read it
correctly but their minds sometimes register those words as
"Life Long Coolant." Coolant dyslexia! The result for many
years has often resulted in sadly neglected cooling systems.
While that's good money for those of us in the repair business, our biggest responsibility to the loyal customers we
try to cultivate is PREVENTATIVE maintenance. The lack of
proper PM on cooling systems extends well beyond leaky
radiators, seeping heater cores and restricted water jackets.
Everything from a heater core that won't heat the cabin to
a big repair bill for leaks in the menagerie of cooling system
related components (i.e. EGR cooler, HP oil cooler, injector
sleeves, etc.) can go bad when coolant is neglected. (Fig 1)

Photo Dave Hobbs

From the very first liquid cooled engines that appeared
around the turn of the 20th century, automotive cooling systems have had one major task; manage engine temperatures.
Too cool and heater performance, drivability, fuel economy
and emissions suffer. Too hot and engine damage may occur
in addition to increased emissions such as NOx. A glance at
your old vocational school textbooks and you'll recall that
all production vehicles use a mixture of 50/50 antifreeze
and water. Ethylene Glycol (EG for short) is the component
in antifreeze used in virtually every OEM's factory coolant
fill. Propylene Glycol (PG for short) is an aftermarket product - no OEMs use it. EG has always had a sweet taste that
made it an attractive toxin for pets to drink. PG is more expensive compared to EG so its primary marketable advantage focused on pet owners. Although its taste is less sweet
and therefore less tempting for pets to drink, PG is still toxic
none the less. Many EG coolants contain embittering agents.
Embittering agents (30 ppm of denatonium benzoate) make
coolant taste absolutely horrible so the pet danger factor is
eliminated. Coolants with embittering agents have been required in California and Oregon for well over a decade but
are not included on the label. Over a dozen more states have
joined California and Oregon since that time with the list
growing.
EG prevents the freezing of the water in subfreezing temperatures and raises the coolant's boiling point. Within the
EG family of coolants only the additive packages vary from
brand to brand. Or at least that's been the mainline view
until more recent times. Since the increase in popularity of
coolant premixes, now the water in premix coolant can vary
between brands and types of coolants. More on the water
variable coming up.

Coolant Dyslexia
Cooling systems are doing more work than ever with
today's vehicles. Turbocharged engines create more horsepower but at a price; more heat. Hotter motor oil and engine compartments mean hotter cooling systems thanks to
the additional heat exchangers in the form of oil coolers and
intercoolers up front with the radiator and A/C condenser.
Recent trends in water cooled EGR in applications ranging
from the little hybrid Toyota Prius to big diesel trucks also

Figure 1: Complications from coolant 'dyslexia': This DEX-COOL disaster occurred from NO maintenance which included a leak to allow air into the system.
The air acted like a catalyst to create rust and rust causes restricted flow through
water jackets and heat exchangers. Core sand from castings would also cause
brown gunk. Those 'complications' have died down on some applications (like
this GM example) only to pop up with other OEMs on different components.
The owner of this vehicle definitely confused "Long Life" with "Life Long" regarding cooling system service.

MACS Service Reports is the official technical publication of the Mobile Air Conditioning Society Worldwide, Inc., P.O. Box 88, Lansdale, PA 19446. The material published in MACS Service Reports expresses the views of the contributors
and not necessarily that of MACS. Every attempt has been made to ensure

May 2017

the accuracy of the content of MACS Service Reports. MACS, however, will
not be responsible for the accuracy of the information published nor will MACS
Worldwide be liable in any way for injury, labor, parts or other expenses resulting
from the use of information appearing in MACS Service Reports.

MACS Service Reports

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2017