Radiator/Charge Air Cooler - Holiday Rambler Imperial 2008 Owner's Manual

CHASSIS INFORMATION — 10
WARNING:
It is advised to shut off the engine
should the engine overheat. It may take
several hours before engine temperature
has lowered to a safe operating range.
Do not remove the coolant reservoir
cap as severe burns may result. Never
add cold water to an overheated engine
as this will cause uneven rapid cooling
and possibly result in further engine
damage.
Freeze Protection:
Coolant freeze protection is checked using a
refractometer for accuracy. This meter checks at
what point the coolant begins to freeze. Refer to
the engine OEM manual for test procedures.
Coolant System - Thawing:
If the coolant system becomes frozen,
the motorhome must be towed. Place the
motorhome in a warm area until completely
thawed. If the engine is operated when the
cooling system is frozen, the engine may
overheat due to insuffi cient coolant circulation.
Once thawed, check the engine, radiator and
related components for damage caused by
expansion of frozen coolant.
244
Coolant Hoses:
Inspect coolant hoses and connections when
checking engine or transmission fl uids. Look for
any signs of chaffi ng at hose restraints or sharp
edges. Indications that hoses have reached the
end of service life include cracking or swelling
around clamps and connections. Oil leaks can
also deteriorate hoses.
Overheating can be caused by a collapsed
hose. Old hoses can also deteriorate on the
inside causing partial clogs reducing cooling
effi ciency. Replace any hose found to be
cracked, swollen or damaged. Periodically
check hose clamp torque.
INSPECT:
Every 12 months - Inspect all hoses,
clamps, and fittings for leaks due to
cracking, softness and loose clamps/
fittings. Look for signs of fluid leaks,
damaged end fittings or ballooning;
chafed, kinked, or crushed hoses; and
loose clamps and fittings. Correct any
deficiencies found.
020165h

Radiator/Charge Air Cooler

The diesel engine uses compression to ignite the
fuel/air charge. To increase compression inside the
combustion chamber (resulting in increased power
output) a turbocharger is added to the engine. The
turbocharger is a paired housing assembly with
impellers inside each housing connected by a
common shaft. One impeller is propelled by the
engine exhaust, which drives the other impeller.
The function of the other impeller is to increase
compression inside the combustion chamber by
forcing air into the intake manifold.
2 00 8 I MP E R I A L
This process works well, however, the intake
air charge is heated two different ways: through
convection by the exhaust gases driving the
turbocharger and when air is compressed. This
negative effect inside the combustion chamber
results in lost power potential. Therefore, a
Charge Air Cooler (CAC) is installed to cool
the intake air before it enters the engine. The
CAC performs the same function as a radiator,
cooling air instead of liquid. Ambient air
passing through the CAC will cool the engine
intake air charge.
After leaving the turbocharger, intake air
is compressed and heated to approximately
300º to 375º F., depending on the engine load
and throttle position. Before air enters the
intake manifold, the CAC cools the intake
air temperature to the engine manufacturer
specifi cations. Lowered intake air temperatures
reduce exhaust emissions, improve fuel
economy and increase horsepower. The CAC
will continually expand and contract up to ¼" as
throttle increases and decreases.
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