MACS Monthly Newsletter - 2017 - APR4

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You can get that specific antifreeze at dealers, although
our view is you can use DexCool, as the DexCool mix has
certainly proved to be compatible with 2-EHA and TT.
These new medium and heavy-duty trucks are primarily for "upfitters," who attach specific design bodies to
them, such as for construction and garbage removal.
That green antifreeze is used only with the 5.2-l diesel,
and GM has made it clear that the specific antifreeze is
essential, however. Why you ask?
First, there is a green propylene glycol antifreeze
around, and if you use that, bad news (engine damage)
says GM. Second, Isuzu provides the diesel engine warranty for GM, and (as has happened with many engines
from outside suppliers) mandates a specific coolant.
Also noteworthy on the new Chevy medium-to-heavy
duty models, the Isuzu diesels have a fuel-to-air fuel
system cooler, which is mounted in front of the rear axle
(FIG. 5).
The diesel fuel cooler is intended to compensate for

Figure 4: New GM anti-freeze is just a single organic acid (2-EHA) for
Isuzu diesels in low-cab-forward Chevy heavy-duty and medium-duty
chassis converted for work uses by upfitters.

Figure 5: Fuel cooler mounted in front of rear axle on low-cab-forward
heavy-duty and medium-duty chassis serves to cool Isuzu diesel fuel as
it flow back to the tank.

That green antifreeze is not the green that GM used in
the early 1990's on Saturn either-that was a low-silicate
"extended life" antifreeze that was picked up from the
Mercedes-Benz shelf, a rather curious selection because
it contained nitrite, an addition that Mercedes found was
helpful in protecting diesel engine cylinder wet liners.
So what is that antifreeze? We had it analyzed and it
turns out that it's just a single organic acid - 2-EHA plus
TT. That differs from DexCool, which has the second organic acid (sebacic acid), and some other antifreezes that
use other ingredients, such as molybdate, along with TT.

higher fuel pressure and temperature (caused by changes
in camshaft timing). The cooler is part of the fuel return
circuit and it reduces temperature of the fuel before it
goes back into the fuel tank.
Those new low cab forward chassis are Class 3 to 5
(3500, 3500 HD, 4500, 4500 HD, 4500 XD, 5500 HD and
5500 XD). The engine lineup also includes a 6.0-liter
gasoline V8, 6.0 CNG/LPG-capable version and a second
Isuzu four-cylinder diesel, with a displacement of 3.0 liters, which also gets that green antifreeze as the OE fill. ■

OTHER ANTIFREEZES
Ford once had at least four anti-freeze formulas worldwide, and is working its way down to one (a Dexcool organic acids type), even though it took a lot of engineering
work on the powertrain cooling systems to do that (and

April 2017

dropping the 5.4-liter V8 and 6.8-liter V-10, among other
things).
Fiat Chrysler's domestic line used "conventional
American green" (called "inorganic additive" technol-

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